According to Guy Croft your cylinder head casting 4372291 is a later US version for unleaded fuel. The inlet ports aren’t the biggest but they are not the smallest either! 41.8mm inlet valves, standard 36mm exhaust valves. The only bigger inlet valves are Abarth version 43.5mm (which I found!) but you need to dry build the engine to check clearance to the piston pocket (especially with Lancia pistons!)
Technical 1978 124 Project
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Technical 1978 124 Project
The head has additional ports for air injection as part of the Federal Emissions control package. European variants didn’t have this. You can plug them if you are not required or bothered about passing a tailpipe emissions test.
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smahaley
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Thank you! I believe that is what the 4 nuts are in the top of the head - you can see them in this pic. They look like there was a spot weld on them to keep them in place.
Normally there would be a pipe connected to these fittings. That allows additional air to be pumped into the engine, usually the exhaust port, to make sure any remaining hydrocarbons are combusted.
You could replace these with a proper blanking plug if needed.
Having viewed your latest pics, I have a number of suggestions/cautions that I'll list for your consideration.
Wear ridge at top of cylinder bores - if this ridge can be felt with your fingernail, it might catch the new stock pattern rings, so it'll need to be removed unless you opt for 'ridge-dodger' type piston rings. As I'm not a fan of ridge cutter tools, I'd opt for careful use of a curved Engineer's scraper to blend out any step, alternatively you might use your Dremel tool with suitable grinding bobs or rotary burrs. I think your cylinder bores need a bit more honing, I can still see shiny patches and some marks that I'd prefer to see addressed further.
I've been trying to figure what might have caused the weird pattern near the top of the cylinders, looks like sort sort of chemical erosion, it was very noticeable after you pressure washed the block (the pic of no.4 cyl. bore made me wonder if there might even be a crack in no.4 bore), but the erosion pattern is still present after honing. I'd be checking further.
New pistons often come without the rings fitted (so that you can check the ring gap in their respective cyl. bores) - don't be too worried about breaking any more rings, new rings are less fragile and it's easier to fit them than to remove them. Iirc, the Hayne's manual advises using thin feeler gauges or thin metal strip to aid in installing the rings in the absence of a proper ring expander tool. Suitable thin metal can be cut from cookie/candy/chocolate tins or canned veg - if you cut a section from a can a little smaller that the piston, you can slit the side and slip this over the piston to assist in sliding the rings into their grooves). Make sure the rings are fitted the correct way up according to the manufacturer's markings.
I still am of the view that your existing pistons might be fine to re-use and to fit them with 'ridge-dodger' type rings if available - this avoids any issues with the new rings catching on any remaining wear ridge at the top of the cyl. bore. I don't see the point in fitting new pistons in worn bores, better to re-bore the cylinders and then get the maximum benefit from the cost of the new pistons. This is an important decision and imho worth taking time to decide which is the better option.
(although you do seem to have made your decision and may even have ordered the pistons - I hope not, reference my much earlier comments about not rushing into buying any parts..
Cylinder block needs further preparation...
Have you removed the coolant drain plug on the block and ensured the hole is clear?
When I mentioned the coolant core/frost plugs, I was referencing them rusting from the inside out. If you haven't removed them I'd advise at least shining a light down the coolant passageways to get a look at their inner surface - don't be fooled by their outer appearance. (a borescope type camera might be ideal for this check.
Have you removed the crankshaft yet? Or did you intend not disturbing it?
Dirt is the big enemy of satisfactory engine work...
I would always remove the crank, even if I intended re-using the existing crank bearing shells. - The cylinder block needs to be properly cleaned - not just the coolant jacket/waterways/drillings but more especially the oil gallery and oilways/drillings.
E.g. there are iirc 6 oil feeds from the cyl. block to the camboxes, any dirt/grit that may have entered these will be pumped up to the camshaft bearings.
The crankshaft main bearings are lubed from the main oil gallery in the block, the oil that reaches the main bearings then has to flow through the main bearing journal oil drillings to reach the con-rod bearings. The oilways in the crank throws act like centrifuges and debris builds up inside the con rod journals - Fiat fitted core plugs (10mm diameter) next to each con rod journal, which are designed to be removed for crank cleaning during overhaul and especially after re-grinding and then new plugs installed.
There are also core plugs in the cyl. block main oil gallery that should ideally be removed for cleaning during engine overhaul.
If you don't want to mess with removing these oilways core plugs (and they can be tricky to remove without causing damage to the surrounding metal which can then make fitting new ones more difficult), then I'd strongly recommend a very, very thorough flush through of all oilways using a decent solvent. Old style 'pipe-cleaners' or small brushes can be used to clean out the crank drillings, try to pump solvent from the main bearing journal holes towards the con rod journal holes.
I am aware that the better solution to these pressed-in oilway plugs is to tap the holes and install threaded plugs, normally done on competition/ race engines but not really necessary for normal road use, I've never seen one pop-out in service unless removed and then badly refitted.
An engine can continue in use for many years without any problem while varnish, sludge and various debris can be accumulating in the oil gallery/oilways without apparent harm. But when an engine is left dormant for a long time, this debris can be loosened/dislodged when the engine is awoken and treated to an oil change, or better yet, an oil system flushing treatment and then can cause problems. Likewise, this debris will likely be loosened /disturbed if any work is carried out on the engine, so it's best to do a thorough clean while it's apart and not just assume it'll be fine...
Crankshaft bearing shells - I'd replace if any signs of wear e.g. surface coating worn through anywhere. It's advisable to pay particular to any pattern of wear on the bearing shells - can indicate other issues that'll need to be addressed. Don't worry too much about slight scratching.
OIl pump - can be checked out according to the Hayne's manual, pay particular attention to the condition of the splines on the pump drive shaft and check their fit in the oil pump drive gear that is driven off the auxiliary drive shaft. Check out the internal splines of this drive gear, they have been known to fail - I usually fitted a new oil pump drive gear unless the gear was perfect. Also check out the oil pump pressure relief valve, it's seating and it's spring. (I've sometimes fitted a spacer under the spring to reset the maximum release pressure, but don't overdo it).
Check the journals on the auxiliary drive shaft for wear, it's gear teeth for wear and it's bearings in the cylinder block - the bearing are replaceable.
Crankshaft - check the condition of the clutch shaft support bearing in the rear of the crankshaft - replace if worn or noisy (it may be possible to gently pop out it's seal and put a little hmp grease in to prolong it's life, then refit the seal. This bearing is often overlooked and if worn can result in a whirring noise when the clutch is disengaged, has confused people who thought the problem was the clutch release bearing or else inside the transmission. If you do need to replace this bearing (they rarely give trouble) make sure the one you obtain actually will fit the nose of the trans. front shaft before you install it...
Cyl. block and cyl. head missing studs - fit studs while engine is apart. If some studs came out when you undid their nuts, remove the nuts and fit the studs - don't do as others often do and refit the nut and stud as it was removed, this will likely result in the stud not being at full depth or tight in the casting and will likely loosen in service, on alloy castings, it can result in a pulled thread when tightened fully.
Cyl. head - I don't like the look of the Helicoil insert you've installed... I suspect you inserted it from the combustion chamber side? The exposed thread represents a sharp edge that can possibly glow red-hot and potentially cause pre-ignition in the cylinder. I'd either re-do it or carefully prise the lowest thread out of the threaded hole, notch it with your dremel tool (it's probably to hard a material to snip with pliers) to remove one coil and then pop the end back in place. Iirc, the end thread should be approx. 1/2 to 1 thread from the end of the hole so that the insert end digs into the surrounding metal to prevent it possibly being wound into the cylinder when refitting spark plugs in future.
Cyl. block - clean out any waterway drillings with a drill bit to remove corrosion. Clean out any threaded bolt holes (10 of them) to ensure no corrosion present and correct torque can be applied when reassembling the engine. Also clean the cyl. head bolt threads for the same reason. ensure no liquid e.g. oil in present in the holes before refitting the cyl. head to prevent a 'hydraulic lock' situation. Check the bolts for 'necking' (stretching) both where the thread starts and along the thread.
Cyl. head - ensure the holes that the cyl head bolts pass through are clean, you don't want any rusty particles being dislodged and getting on the gasket sealing surface (I've seen this happen on 'quick' head jobs, but you seem to have this already covered in your cleaning).
You mention some of the new valves were loose in some of their guides? I wasn't aware you were replacing the valves, I thought you were just going to clean them and then lap them in the check them...
One of your pics of the cyl. head shows a cam follower and shim in the background - that shim looks 'dodgy', I'd replace any dubious shims, also check any used shims being re-used are still perfectly flat, - hollow shims can quickly destroy a cam lobe.
Your pic of the cylinder head shows all valves in place, I'm guessing these are the new valves? And you haven't yet fitted new valve stem oil seals? I would only fit the valve stem oil seals after all valve grinding/lapping work has been completed and everything has been cleaned - this avoids the risk of any grinding paste grit getting trapped in the guide or under the new oil seal. Iirc the lower spring seats (a flat hardened washer topped by a stepped washer/ring, have to be fitted before the valve stem oil seals are installed, they can't be fitted afterwards, won't fit over the valve stem oil seals. Be gentle removing the old seals (I just twist them with a pliers) and fitting the new ones (should just push into place using a suitably sized tube or socket and maybe a gentle tap).
Check the condition of the valve collars and their retainers (collets). Try 2 retainers on a valve to check they fit correctly Check your retainers are the correct type for the valves you'll be using (some valves have 1 round groove, others have 2 rounded grooves, others have 1 deep square groove). With 2 retainers test-fitted on a valve, there should be small gap - when installing a valve, I try to get the gap equal on each side of the valve stem.
Check that none of the retainers have started to 'flatten out' or are showing signs of descending into the valve collar, i.e. test fit a collar and retainers on each valve (with the valve out of the cyl. head) and check that the valve stem is protruding the same amount on each valve.
Having said all this, Fiat twin-cam engines are pretty robust in the valve train area and give little trouble (unless of course, the ignoranti have previously been in there...).
The design of the Fiat t/cam valve operation is one of the best around, the use of cam buckets removes any side thrust on the valve stem leading to much reduced valve stem/guide wear in service.
I wouldn't worry about a little play, the oil seals should prevent excessive oil being drawn down to valve stem and then being burned - the pics of your engine as you disassembled it show no signs of excess valve stem/guide wear or consequent oil consumption.
Wear ridge at top of cylinder bores - if this ridge can be felt with your fingernail, it might catch the new stock pattern rings, so it'll need to be removed unless you opt for 'ridge-dodger' type piston rings. As I'm not a fan of ridge cutter tools, I'd opt for careful use of a curved Engineer's scraper to blend out any step, alternatively you might use your Dremel tool with suitable grinding bobs or rotary burrs. I think your cylinder bores need a bit more honing, I can still see shiny patches and some marks that I'd prefer to see addressed further.
I've been trying to figure what might have caused the weird pattern near the top of the cylinders, looks like sort sort of chemical erosion, it was very noticeable after you pressure washed the block (the pic of no.4 cyl. bore made me wonder if there might even be a crack in no.4 bore), but the erosion pattern is still present after honing. I'd be checking further.
New pistons often come without the rings fitted (so that you can check the ring gap in their respective cyl. bores) - don't be too worried about breaking any more rings, new rings are less fragile and it's easier to fit them than to remove them. Iirc, the Hayne's manual advises using thin feeler gauges or thin metal strip to aid in installing the rings in the absence of a proper ring expander tool. Suitable thin metal can be cut from cookie/candy/chocolate tins or canned veg - if you cut a section from a can a little smaller that the piston, you can slit the side and slip this over the piston to assist in sliding the rings into their grooves). Make sure the rings are fitted the correct way up according to the manufacturer's markings.
I still am of the view that your existing pistons might be fine to re-use and to fit them with 'ridge-dodger' type rings if available - this avoids any issues with the new rings catching on any remaining wear ridge at the top of the cyl. bore. I don't see the point in fitting new pistons in worn bores, better to re-bore the cylinders and then get the maximum benefit from the cost of the new pistons. This is an important decision and imho worth taking time to decide which is the better option.
(although you do seem to have made your decision and may even have ordered the pistons - I hope not, reference my much earlier comments about not rushing into buying any parts..
Cylinder block needs further preparation...
Have you removed the coolant drain plug on the block and ensured the hole is clear?
When I mentioned the coolant core/frost plugs, I was referencing them rusting from the inside out. If you haven't removed them I'd advise at least shining a light down the coolant passageways to get a look at their inner surface - don't be fooled by their outer appearance. (a borescope type camera might be ideal for this check.
Have you removed the crankshaft yet? Or did you intend not disturbing it?
Dirt is the big enemy of satisfactory engine work...
I would always remove the crank, even if I intended re-using the existing crank bearing shells. - The cylinder block needs to be properly cleaned - not just the coolant jacket/waterways/drillings but more especially the oil gallery and oilways/drillings.
E.g. there are iirc 6 oil feeds from the cyl. block to the camboxes, any dirt/grit that may have entered these will be pumped up to the camshaft bearings.
The crankshaft main bearings are lubed from the main oil gallery in the block, the oil that reaches the main bearings then has to flow through the main bearing journal oil drillings to reach the con-rod bearings. The oilways in the crank throws act like centrifuges and debris builds up inside the con rod journals - Fiat fitted core plugs (10mm diameter) next to each con rod journal, which are designed to be removed for crank cleaning during overhaul and especially after re-grinding and then new plugs installed.
There are also core plugs in the cyl. block main oil gallery that should ideally be removed for cleaning during engine overhaul.
If you don't want to mess with removing these oilways core plugs (and they can be tricky to remove without causing damage to the surrounding metal which can then make fitting new ones more difficult), then I'd strongly recommend a very, very thorough flush through of all oilways using a decent solvent. Old style 'pipe-cleaners' or small brushes can be used to clean out the crank drillings, try to pump solvent from the main bearing journal holes towards the con rod journal holes.
I am aware that the better solution to these pressed-in oilway plugs is to tap the holes and install threaded plugs, normally done on competition/ race engines but not really necessary for normal road use, I've never seen one pop-out in service unless removed and then badly refitted.
An engine can continue in use for many years without any problem while varnish, sludge and various debris can be accumulating in the oil gallery/oilways without apparent harm. But when an engine is left dormant for a long time, this debris can be loosened/dislodged when the engine is awoken and treated to an oil change, or better yet, an oil system flushing treatment and then can cause problems. Likewise, this debris will likely be loosened /disturbed if any work is carried out on the engine, so it's best to do a thorough clean while it's apart and not just assume it'll be fine...
Crankshaft bearing shells - I'd replace if any signs of wear e.g. surface coating worn through anywhere. It's advisable to pay particular to any pattern of wear on the bearing shells - can indicate other issues that'll need to be addressed. Don't worry too much about slight scratching.
OIl pump - can be checked out according to the Hayne's manual, pay particular attention to the condition of the splines on the pump drive shaft and check their fit in the oil pump drive gear that is driven off the auxiliary drive shaft. Check out the internal splines of this drive gear, they have been known to fail - I usually fitted a new oil pump drive gear unless the gear was perfect. Also check out the oil pump pressure relief valve, it's seating and it's spring. (I've sometimes fitted a spacer under the spring to reset the maximum release pressure, but don't overdo it).
Check the journals on the auxiliary drive shaft for wear, it's gear teeth for wear and it's bearings in the cylinder block - the bearing are replaceable.
Crankshaft - check the condition of the clutch shaft support bearing in the rear of the crankshaft - replace if worn or noisy (it may be possible to gently pop out it's seal and put a little hmp grease in to prolong it's life, then refit the seal. This bearing is often overlooked and if worn can result in a whirring noise when the clutch is disengaged, has confused people who thought the problem was the clutch release bearing or else inside the transmission. If you do need to replace this bearing (they rarely give trouble) make sure the one you obtain actually will fit the nose of the trans. front shaft before you install it...
Cyl. block and cyl. head missing studs - fit studs while engine is apart. If some studs came out when you undid their nuts, remove the nuts and fit the studs - don't do as others often do and refit the nut and stud as it was removed, this will likely result in the stud not being at full depth or tight in the casting and will likely loosen in service, on alloy castings, it can result in a pulled thread when tightened fully.
Cyl. head - I don't like the look of the Helicoil insert you've installed... I suspect you inserted it from the combustion chamber side? The exposed thread represents a sharp edge that can possibly glow red-hot and potentially cause pre-ignition in the cylinder. I'd either re-do it or carefully prise the lowest thread out of the threaded hole, notch it with your dremel tool (it's probably to hard a material to snip with pliers) to remove one coil and then pop the end back in place. Iirc, the end thread should be approx. 1/2 to 1 thread from the end of the hole so that the insert end digs into the surrounding metal to prevent it possibly being wound into the cylinder when refitting spark plugs in future.
Cyl. block - clean out any waterway drillings with a drill bit to remove corrosion. Clean out any threaded bolt holes (10 of them) to ensure no corrosion present and correct torque can be applied when reassembling the engine. Also clean the cyl. head bolt threads for the same reason. ensure no liquid e.g. oil in present in the holes before refitting the cyl. head to prevent a 'hydraulic lock' situation. Check the bolts for 'necking' (stretching) both where the thread starts and along the thread.
Cyl. head - ensure the holes that the cyl head bolts pass through are clean, you don't want any rusty particles being dislodged and getting on the gasket sealing surface (I've seen this happen on 'quick' head jobs, but you seem to have this already covered in your cleaning).
You mention some of the new valves were loose in some of their guides? I wasn't aware you were replacing the valves, I thought you were just going to clean them and then lap them in the check them...
One of your pics of the cyl. head shows a cam follower and shim in the background - that shim looks 'dodgy', I'd replace any dubious shims, also check any used shims being re-used are still perfectly flat, - hollow shims can quickly destroy a cam lobe.
Your pic of the cylinder head shows all valves in place, I'm guessing these are the new valves? And you haven't yet fitted new valve stem oil seals? I would only fit the valve stem oil seals after all valve grinding/lapping work has been completed and everything has been cleaned - this avoids the risk of any grinding paste grit getting trapped in the guide or under the new oil seal. Iirc the lower spring seats (a flat hardened washer topped by a stepped washer/ring, have to be fitted before the valve stem oil seals are installed, they can't be fitted afterwards, won't fit over the valve stem oil seals. Be gentle removing the old seals (I just twist them with a pliers) and fitting the new ones (should just push into place using a suitably sized tube or socket and maybe a gentle tap).
Check the condition of the valve collars and their retainers (collets). Try 2 retainers on a valve to check they fit correctly Check your retainers are the correct type for the valves you'll be using (some valves have 1 round groove, others have 2 rounded grooves, others have 1 deep square groove). With 2 retainers test-fitted on a valve, there should be small gap - when installing a valve, I try to get the gap equal on each side of the valve stem.
Check that none of the retainers have started to 'flatten out' or are showing signs of descending into the valve collar, i.e. test fit a collar and retainers on each valve (with the valve out of the cyl. head) and check that the valve stem is protruding the same amount on each valve.
Having said all this, Fiat twin-cam engines are pretty robust in the valve train area and give little trouble (unless of course, the ignoranti have previously been in there...).
The design of the Fiat t/cam valve operation is one of the best around, the use of cam buckets removes any side thrust on the valve stem leading to much reduced valve stem/guide wear in service.
I wouldn't worry about a little play, the oil seals should prevent excessive oil being drawn down to valve stem and then being burned - the pics of your engine as you disassembled it show no signs of excess valve stem/guide wear or consequent oil consumption.
Last edited:
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smahaley
Member
Good day, all -
First, a video of my crankshaft prior to removal.
Second, a video of the cylinder head.
Now some additional specifics:
Cylinders: Yes, I am going to do something about the ridge at the top. Thanks for the advice on that. I will do another pass with the honing tool, and will share a photo after that. I don't think there is a crack in anything, but will reexamine VERY closely.
Pistons: As it turned out, I ordered the wrong size! So, I am going to use the existing pistons, but have ordered new rings.
Block: Yes, I removed the coolant drain plug, and have examined the water galleries, and they all look good (post pressure washing). I'll put some compressed air on the water and oil passageways to make sure.
Head: Thanks, and I'm going to do another pass with some solvent to ensure the passageways are clear there as well. I have yet to lap the new valves, so will remove the oil seals per your advice prior to any of that. I'll reclean everything, including the shims on the caps/buckets, prior to reassembly. I'm expecting that with the new valves I will likely need to order some different shims in order to reach the correct clearances.
Crankshaft bearing shells all look good to me, post extraction. I'm careful to keep everything labeled and oriented. All oilways look clear.
"Ignoranti". Thank you, I'll be keeping that for use later!
I liked your videos 
And was pleased to see you're using you eyes to notice all the little things that the 'ignoranti' miss - such as the main bearing caps being numbered to match the cylinder block (because they're 'line-bored') and therefore should not be fitted to a different cyl. block, also you saw how Fiat mark the order of the main bearing caps.
I still suspect someone has been in there before you - I've never seen main bearing bolt heads with different markings, every Fiat engine I've seen has bolts either all marked Fiat or else all marked with the same but different supplier's mark.
Crank journals all looked good (as far as I could tell from the video) and providing all the bearing shells are not worn through to the underlay, you might be able to just re-use and reassemble after careful cleaning.
Whenever I strip an engine and find the bearing shells looking good, I often don't bother with measuring the journals and either just re-use the existing shells or fit a new set of the same size. You could use 'Plastigauge as a quick check on bearing clearance or else measure/have someone measure the crank journals for wear/ovality if you wish.
Some might recommend taking the crank to a machine shop to have the journals measured, or they might recommend having the journals 'polished' before fitting new bearing shells - my view is it may be better not to let modern machinists near an older model crank and why polish journals - if the existing, bedded-in surface finish hasn't torn up the old bearings, it's not likely to tear-up the new ones, why mess with the surface finish and remove metal?
As I said before, I don't like removing metal unnecessarily (crank journals, cylinder bores, valve seats/faces, cylinder head/block gasket surfaces, manifold gasket surfaces etc.).
I suspect, given the gasket witness marks on your cyl. head surface, that your cyl. head won't need to be skimmed, I'd just double-check using a decently accurate straight edge and a light. Fiat dealership workshops actually had special tools - profile gauges that were positioned in the combustion chamber, to be used to check if the cyl. head could be skimmed or to determine if it had been skimmed previously and by how much.
I never liked skimming heads that had part of the valve seat protruding/less-supported (we had our own head resurfacing machine in-house).
One thing I did notice in your video on the crankshaft removal that has me a little concerned- @ approx. 2mins 5sec in, where you're looking into the crankcase up no.4 cylinder bore, is that a crack or just some casting flash running out from the bottom of no. 4 cylinder? I hope not.
There are 'crack-testing' spray kits available, also machine shop have equipment to check for cracks (e.g.' Magnaflux', 'Black-light' test etc.).
An old trick for testing for a crack in a casting - wash suspect area with paraffin/diesel/home heating oil/kerosene, wipe clean using a solvent e.g. gasoline, then shake some powder (e.g. Talcum powder) over the area, brush excess away, if a crack is present, the powder will adhere to any oil absorbed into and remaining in the crack leaving a trace of powder adhering along the location of the crack.
Loosening main bearing cap bolts - can be loosened fully one by one in any order, no need to follow any pattern.
But it is advisable to follow the recommended pattern when loosening and tightening cylinder head bolts, flywheel bolts and anything that has a circular ring of bolts/nuts or long items such as intake/exhaust manifolds to avoid unduly stressing a component especially a casting. It's usually a good practice to tighten the bolts in 2 or 3 stages of increasing tightening torque, same as for cylinder head tightening. One thing I like to do is try re-torqueing cylinder head bolts and manifold nuts again after leaving them for say, 24 hours, if I'm not pressed for time - I just loosen each one in the correct tightening order by 1/2 turn and re-torque with the wrench moving, if you stop moving and then resume turning the wrench will likely click/indicate correct tightness straight away without further angular movement resulting in an incorrect torque being applied. I don't do this to crank main or rod bearing bolts/nuts or flywheel bolts, crank pulley nut, just those locations that use a gasket that crushes when installed. Or course I don't do this with torque-to-yield bolts! which afaik? were used on the last of the Spider twin-cam engines.
When I previously mentioned checking out the coolant frost/expansion/core plugs - I meant checking their surfaces inside the cyl. block (i.e. their back, unseen faces). They can appear fine on the outside and be just about to fail and they're a bit awkward to replace in situ. You don't mention if you've removed the coolant cover plate on the back of the cyl. block yet, or perhaps the engine stand is blocking access?
Please make ensure you at least give the crank oilways/drillings a really good wash and flush through if you don't want to risk removing the small (10mm?) oil drilling expansion plugs (you can see these on either? side of each rod journal of the crankshaft.
I appreciate the mention and the thanks
(but would, of course, prefer cash, or better still, gold).
And was pleased to see you're using you eyes to notice all the little things that the 'ignoranti' miss - such as the main bearing caps being numbered to match the cylinder block (because they're 'line-bored') and therefore should not be fitted to a different cyl. block, also you saw how Fiat mark the order of the main bearing caps.
I still suspect someone has been in there before you - I've never seen main bearing bolt heads with different markings, every Fiat engine I've seen has bolts either all marked Fiat or else all marked with the same but different supplier's mark.
Crank journals all looked good (as far as I could tell from the video) and providing all the bearing shells are not worn through to the underlay, you might be able to just re-use and reassemble after careful cleaning.
Whenever I strip an engine and find the bearing shells looking good, I often don't bother with measuring the journals and either just re-use the existing shells or fit a new set of the same size. You could use 'Plastigauge as a quick check on bearing clearance or else measure/have someone measure the crank journals for wear/ovality if you wish.
Some might recommend taking the crank to a machine shop to have the journals measured, or they might recommend having the journals 'polished' before fitting new bearing shells - my view is it may be better not to let modern machinists near an older model crank and why polish journals - if the existing, bedded-in surface finish hasn't torn up the old bearings, it's not likely to tear-up the new ones, why mess with the surface finish and remove metal?
As I said before, I don't like removing metal unnecessarily (crank journals, cylinder bores, valve seats/faces, cylinder head/block gasket surfaces, manifold gasket surfaces etc.).
I suspect, given the gasket witness marks on your cyl. head surface, that your cyl. head won't need to be skimmed, I'd just double-check using a decently accurate straight edge and a light. Fiat dealership workshops actually had special tools - profile gauges that were positioned in the combustion chamber, to be used to check if the cyl. head could be skimmed or to determine if it had been skimmed previously and by how much.
I never liked skimming heads that had part of the valve seat protruding/less-supported (we had our own head resurfacing machine in-house).
One thing I did notice in your video on the crankshaft removal that has me a little concerned- @ approx. 2mins 5sec in, where you're looking into the crankcase up no.4 cylinder bore, is that a crack or just some casting flash running out from the bottom of no. 4 cylinder? I hope not.
There are 'crack-testing' spray kits available, also machine shop have equipment to check for cracks (e.g.' Magnaflux', 'Black-light' test etc.).
An old trick for testing for a crack in a casting - wash suspect area with paraffin/diesel/home heating oil/kerosene, wipe clean using a solvent e.g. gasoline, then shake some powder (e.g. Talcum powder) over the area, brush excess away, if a crack is present, the powder will adhere to any oil absorbed into and remaining in the crack leaving a trace of powder adhering along the location of the crack.
Loosening main bearing cap bolts - can be loosened fully one by one in any order, no need to follow any pattern.
But it is advisable to follow the recommended pattern when loosening and tightening cylinder head bolts, flywheel bolts and anything that has a circular ring of bolts/nuts or long items such as intake/exhaust manifolds to avoid unduly stressing a component especially a casting. It's usually a good practice to tighten the bolts in 2 or 3 stages of increasing tightening torque, same as for cylinder head tightening. One thing I like to do is try re-torqueing cylinder head bolts and manifold nuts again after leaving them for say, 24 hours, if I'm not pressed for time - I just loosen each one in the correct tightening order by 1/2 turn and re-torque with the wrench moving, if you stop moving and then resume turning the wrench will likely click/indicate correct tightness straight away without further angular movement resulting in an incorrect torque being applied. I don't do this to crank main or rod bearing bolts/nuts or flywheel bolts, crank pulley nut, just those locations that use a gasket that crushes when installed. Or course I don't do this with torque-to-yield bolts! which afaik? were used on the last of the Spider twin-cam engines.
When I previously mentioned checking out the coolant frost/expansion/core plugs - I meant checking their surfaces inside the cyl. block (i.e. their back, unseen faces). They can appear fine on the outside and be just about to fail and they're a bit awkward to replace in situ. You don't mention if you've removed the coolant cover plate on the back of the cyl. block yet, or perhaps the engine stand is blocking access?
Please make ensure you at least give the crank oilways/drillings a really good wash and flush through if you don't want to risk removing the small (10mm?) oil drilling expansion plugs (you can see these on either? side of each rod journal of the crankshaft.
I appreciate the mention and the thanks
(but would, of course, prefer cash, or better still, gold
).
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Re: your cylinder head video -
The valve wiggle test is actually an approved way to test for valve stem/guide wear/clearance on some engines - but it's done in a more accurate way - the valve is held open by a set amount, usually by the maximum valve lift for that engine and the side movement at the rim of the valve is measured using a dial-test-indicator (it can be a bit tricky to set up the DTI so as to get an accurate and repeatable reading).
The way you show checking the valve wiggle is with the valve open by more than the normal valve lift for your engine iirc, max valve lift is c. 9.5mm. So it's a bit bit like waving a long stick versus a short stick - the same angular movement will be magnified by the longer stick. I reckon if you open your valves on no.4 cyl. by only 9.5 mm, the wiggle will be reduced considerably.
I don't think you need to renew any valve guides but it's your choice.
Another option to reduce valve stem clearance might be to have the existing errant valve guide 'knurled' internally, this is possible on some engines, I'm not sure about it's suitability on Fiat valve guides.
There are also thin-wall sleeves that can be pressed into a bored-out valve guide bore to re-size them but likely cheaper to just fit new standard valve guides, bearing in mind that you may then have to have the valve seat/s cut, but you might get away with just grinding/lapping-in your new valves.
The valve wiggle test is actually an approved way to test for valve stem/guide wear/clearance on some engines - but it's done in a more accurate way - the valve is held open by a set amount, usually by the maximum valve lift for that engine and the side movement at the rim of the valve is measured using a dial-test-indicator (it can be a bit tricky to set up the DTI so as to get an accurate and repeatable reading).
The way you show checking the valve wiggle is with the valve open by more than the normal valve lift for your engine iirc, max valve lift is c. 9.5mm. So it's a bit bit like waving a long stick versus a short stick - the same angular movement will be magnified by the longer stick. I reckon if you open your valves on no.4 cyl. by only 9.5 mm, the wiggle will be reduced considerably.
I don't think you need to renew any valve guides but it's your choice.
Another option to reduce valve stem clearance might be to have the existing errant valve guide 'knurled' internally, this is possible on some engines, I'm not sure about it's suitability on Fiat valve guides.
There are also thin-wall sleeves that can be pressed into a bored-out valve guide bore to re-size them but likely cheaper to just fit new standard valve guides, bearing in mind that you may then have to have the valve seat/s cut, but you might get away with just grinding/lapping-in your new valves.
Hi
Looking at the video of the crank, the main bearing cap bolts seem to be two different types. Some are stamped Grade 10.9 and others are not. This is very unusual all bolts should be the same
If it were me I would replace all these fastners as they are not that expensive, the history is unknown and if they let go goodbye engine!
I would also replace the bearing shells ad they are not expensive. They can sometimes warp when the clamp load is released and will never refit properly.
You really need to start measuring stuff and compare to the specifications and wear limits. Data driven decision making beats guessing hands down!
You will have already spent quite a bit of money getting this far, if you don’t measure the various components you could end up wasting what you have spent and redoing the job.
I would also replace the cylinder head bolts, I remember these being pricey 10 years ago but they are essential to get the head to seal to the block effectively
The crank journals look ok but you need to measure them to see what size bearings to buy. You may be lucky snd the sizes are sometimes stamped into the rear surface of the shell
You can check if the head is flat using a sheet of glass or steel rule and feeler guage as recommended by 124BC
You can clean it up using emery paper say 500-800 grit on a flat surface (granite worktop, glass or at a push 20mm thick MDF is usually pretty flat)
You spotted the ID marks on the main bearing caps, the conrods should have these and go back in the orientation and location they came from. Its very easy to get parts mixed up and refitted incorrectly
Take loads of photos as you go as a useful reference.
I forgot to mention the thick washers that go under the headbolts are really important.Hi
Looking at the video of the crank, the main bearing cap bolts seem to be two different types. Some are stamped Grade 10.9 and others are not. This is very unusual all bolts should be the same
If it were me I would replace all these fastners as they are not that expensive, the history is unknown and if they let go goodbye engine!
I would also replace the bearing shells ad they are not expensive. They can sometimes warp when the clamp load is released and will never refit properly.
You really need to start measuring stuff and compare to the specifications and wear limits. Data driven decision making beats guessing hands down!
You will have already spent quite a bit of money getting this far, if you don’t measure the various components you could end up wasting what you have spent and redoing the job.
I would also replace the cylinder head bolts, I remember these being pricey 10 years ago but they are essential to get the head to seal to the block effectively
The crank journals look ok but you need to measure them to see what size bearings to buy. You may be lucky snd the sizes are sometimes stamped into the rear surface of the shell
You can check if the head is flat using a sheet of glass or steel rule and feeler guage as recommended by 124BC
You can clean it up using emery paper say 500-800 grit on a flat surface (granite worktop, glass or at a push 20mm thick MDF is usually pretty flat)
You spotted the ID marks on the main bearing caps, the conrods should have these and go back in the orientation and location they came from. Its very easy to get parts mixed up and refitted incorrectly
Take loads of photos as you go as a useful reference.
They have a small radius on the inner diameter on one side. This needs to go next to the head bolts head. The radius is to provide clearance for the underside if the headbolt. Without this you will have a stress raiser and potential early failure of the fastner.
Flywheel bolts and mounting also need carefully checking as these had a tendency to fatigue crack on some models. Later versions went to larger bolts M12 ilo M10 I think
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smahaley
Member
Thanks for this - I'll measure and re-wiggle. My suspicion is that the wiggle isn't that pronounced, and that I'll just go with the current guides, lap the valves, clean and reassemble (with adjusted shims as needed) the head.Re: your cylinder head video -
The valve wiggle test is actually an approved way to test for valve stem/guide wear/clearance on some engines - but it's done in a more accurate way - the valve is held open by a set amount, usually by the maximum valve lift for that engine and the side movement at the rim of the valve is measured using a dial-test-indicator (it can be a bit tricky to set up the DTI so as to get an accurate and repeatable reading).
The way you show checking the valve wiggle is with the valve open by more than the normal valve lift for your engine iirc, max valve lift is c. 9.5mm. So it's a bit bit like waving a long stick versus a short stick - the same angular movement will be magnified by the longer stick. I reckon if you open your valves on no.4 cyl. by only 9.5 mm, the wiggle will be reduced considerably.
I don't think you need to renew any valve guides but it's your choice.
Another option to reduce valve stem clearance might be to have the existing errant valve guide 'knurled' internally, this is possible on some engines, I'm not sure about it's suitability on Fiat valve guides.
There are also thin-wall sleeves that can be pressed into a bored-out valve guide bore to re-size them but likely cheaper to just fit new standard valve guides, bearing in mind that you may then have to have the valve seat/s cut, but you might get away with just grinding/lapping-in your new valves.
Original Fiat fasteners are very good and reliable. They come with afaik, 2 head markings, 'Fiat' on the older ones and 'SBE' on the later ones. (there might be some other markings used on later models).
I've never changed the main bearing cap bolts on any Fiat T/cam engine, as long as your's are undamaged they should be fine to re-use. I've never seen a Fiat t/cam engine that had failed where m/b bolt failure was the initial cause. Even Midwest-Bayless sell used m/b bolts!
I also don't routinely change rod bearing cap bolts/nuts, Fiat ones are v. good. Many people recommend going aftermarket/upgrading e.g. using ARP fasteners. I'm not convinced. There are various ingenious features incorporated in the stock Fiat bolts used in hi-stress areas, aftermarket alternatives may not have these same features. Having a higher tensile strength means little and may indeed be undesirable in some applications.
Cylinder head bolts are fit to re-use imho if they are free of defects, especially 'necking' (stretched threads resulting in a reduced diameter) in the threaded section, pay particular attention to the area of thread just above that which was originally engaged with the block threads.
Midwest-Bayless even state that their replacement bolt sets are not made to the original pattern but they'll fit and work!
The difference is that original Fiat cyl. head bolts have their threads rolled, not cut, this leaves a small section of the plain part of the bolt at the same diameter as the root (smallest) diameter of the thread which then smoothly increases to the full diameter of the plain section of the bolt, thereby avoiding 'stress-raisers'.
Cylinder head bolts aren't going to all fail together causing the head to blown off! The only time I've had a Fiat head bolt fail was when a bad batch, or possibly overtightened at the factory, bolts got through and these failed when the cylinder heads were being re-torqued at the 1st service (didn't even have to remove the heads to replace the failed bolt/s). I wouldn't worry about re-using the original bolts, but I would again emphasize the importance of ensuring that the cyl. head bolt threads in the cyl. block face are clean and rust-free - it's worth getting a thread tap to do this (10 x 1.25mm thread size). (Vickauto have one listed for $9.70 but they're out of stock).
However, in high stress applications, I.e. crank rod caps, main bearing caps and flywheel, I won't re-use fasteners that have even surface rust, so these fasteners once cleaned/degreased, should be oiled or otherwise protected to prevent corrosion.
Be careful about using the correct tightening torque figures for your exact engine - e.g. iirc, on the 1756cc engine (which iirc is what is in Op's car) there were some changes to main bearing torque figures, these bolts are not all tightened to the same figure.
Consider this - all the fasteners in your engine including main bearing cap bolts, rod bearing cap bolts/nuts, flywheel bolts and cyl. head bolts were doing their job just fine up to now, none had failed, so as long as they're undamaged they should be fine to re-use. But it's your choice, your money...
I've never changed the main bearing cap bolts on any Fiat T/cam engine, as long as your's are undamaged they should be fine to re-use. I've never seen a Fiat t/cam engine that had failed where m/b bolt failure was the initial cause. Even Midwest-Bayless sell used m/b bolts!
I also don't routinely change rod bearing cap bolts/nuts, Fiat ones are v. good. Many people recommend going aftermarket/upgrading e.g. using ARP fasteners. I'm not convinced. There are various ingenious features incorporated in the stock Fiat bolts used in hi-stress areas, aftermarket alternatives may not have these same features. Having a higher tensile strength means little and may indeed be undesirable in some applications.
Cylinder head bolts are fit to re-use imho if they are free of defects, especially 'necking' (stretched threads resulting in a reduced diameter) in the threaded section, pay particular attention to the area of thread just above that which was originally engaged with the block threads.
Midwest-Bayless even state that their replacement bolt sets are not made to the original pattern but they'll fit and work!
The difference is that original Fiat cyl. head bolts have their threads rolled, not cut, this leaves a small section of the plain part of the bolt at the same diameter as the root (smallest) diameter of the thread which then smoothly increases to the full diameter of the plain section of the bolt, thereby avoiding 'stress-raisers'.
Cylinder head bolts aren't going to all fail together causing the head to blown off! The only time I've had a Fiat head bolt fail was when a bad batch, or possibly overtightened at the factory, bolts got through and these failed when the cylinder heads were being re-torqued at the 1st service (didn't even have to remove the heads to replace the failed bolt/s). I wouldn't worry about re-using the original bolts, but I would again emphasize the importance of ensuring that the cyl. head bolt threads in the cyl. block face are clean and rust-free - it's worth getting a thread tap to do this (10 x 1.25mm thread size). (Vickauto have one listed for $9.70 but they're out of stock).
However, in high stress applications, I.e. crank rod caps, main bearing caps and flywheel, I won't re-use fasteners that have even surface rust, so these fasteners once cleaned/degreased, should be oiled or otherwise protected to prevent corrosion.
Be careful about using the correct tightening torque figures for your exact engine - e.g. iirc, on the 1756cc engine (which iirc is what is in Op's car) there were some changes to main bearing torque figures, these bolts are not all tightened to the same figure.
Consider this - all the fasteners in your engine including main bearing cap bolts, rod bearing cap bolts/nuts, flywheel bolts and cyl. head bolts were doing their job just fine up to now, none had failed, so as long as they're undamaged they should be fine to re-use. But it's your choice, your money...
Many good points
Rolled thread bolts definitely preferred for high stress applications
I followed Guy Crofts advice at the time (see photos) as I use the full rpm range of the engine regularly (Sonic pleasure!)
It also depends on how you are going to use the engine, what level of performance it has, budget etc. It also depends on the age and history of the engine
My head bolts were Ribe type socket head but these may not be available everywhere. I think at the time were around £45 a set.
Agreed all bolts wont fail simultaneously but you wont spot fatigue cracks, the bolts may fail when re torquing then you have to pull the engine apart again. Or it may relax or fail if n service causing the head gasket to leak
It depends on your appetite for risk and cost vs benefit!
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smahaley
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Yes - I agree on these points. I raced a car into which we put ARP studs, but that was a 'high pressure' situation with a lot of stress on the motor. I don't expect to be doing that - and I did some reading about the 2 types of bolts I have on the crank: Fiat and Lobo. Apparently Lobo were / are a reputable EU manufacturer and Fiat used their bolts in their builds (is my understanding from the completely believable WWW in all cases
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smahaley
Member
Okay I'm working on sending gold (lol).I liked your videos
And was pleased to see you're using you eyes to notice all the little things that the 'ignoranti' miss - such as the main bearing caps being numbered to match the cylinder block (because they're 'line-bored') and therefore should not be fitted to a different cyl. block, also you saw how Fiat mark the order of the main bearing caps.
I still suspect someone has been in there before you - I've never seen main bearing bolt heads with different markings, every Fiat engine I've seen has bolts either all marked Fiat or else all marked with the same but different supplier's mark.
Crank journals all looked good (as far as I could tell from the video) and providing all the bearing shells are not worn through to the underlay, you might be able to just re-use and reassemble after careful cleaning.
Whenever I strip an engine and find the bearing shells looking good, I often don't bother with measuring the journals and either just re-use the existing shells or fit a new set of the same size. You could use 'Plastigauge as a quick check on bearing clearance or else measure/have someone measure the crank journals for wear/ovality if you wish.
Some might recommend taking the crank to a machine shop to have the journals measured, or they might recommend having the journals 'polished' before fitting new bearing shells - my view is it may be better not to let modern machinists near an older model crank and why polish journals - if the existing, bedded-in surface finish hasn't torn up the old bearings, it's not likely to tear-up the new ones, why mess with the surface finish and remove metal?
As I said before, I don't like removing metal unnecessarily (crank journals, cylinder bores, valve seats/faces, cylinder head/block gasket surfaces, manifold gasket surfaces etc.).
I suspect, given the gasket witness marks on your cyl. head surface, that your cyl. head won't need to be skimmed, I'd just double-check using a decently accurate straight edge and a light. Fiat dealership workshops actually had special tools - profile gauges that were positioned in the combustion chamber, to be used to check if the cyl. head could be skimmed or to determine if it had been skimmed previously and by how much.
I never liked skimming heads that had part of the valve seat protruding/less-supported (we had our own head resurfacing machine in-house).
One thing I did notice in your video on the crankshaft removal that has me a little concerned- @ approx. 2mins 5sec in, where you're looking into the crankcase up no.4 cylinder bore, is that a crack or just some casting flash running out from the bottom of no. 4 cylinder? I hope not.
There are 'crack-testing' spray kits available, also machine shop have equipment to check for cracks (e.g.' Magnaflux', 'Black-light' test etc.).
An old trick for testing for a crack in a casting - wash suspect area with paraffin/diesel/home heating oil/kerosene, wipe clean using a solvent e.g. gasoline, then shake some powder (e.g. Talcum powder) over the area, brush excess away, if a crack is present, the powder will adhere to any oil absorbed into and remaining in the crack leaving a trace of powder adhering along the location of the crack.
Loosening main bearing cap bolts - can be loosened fully one by one in any order, no need to follow any pattern.
But it is advisable to follow the recommended pattern when loosening and tightening cylinder head bolts, flywheel bolts and anything that has a circular ring of bolts/nuts or long items such as intake/exhaust manifolds to avoid unduly stressing a component especially a casting. It's usually a good practice to tighten the bolts in 2 or 3 stages of increasing tightening torque, same as for cylinder head tightening. One thing I like to do is try re-torqueing cylinder head bolts and manifold nuts again after leaving them for say, 24 hours, if I'm not pressed for time - I just loosen each one in the correct tightening order by 1/2 turn and re-torque with the wrench moving, if you stop moving and then resume turning the wrench will likely click/indicate correct tightness straight away without further angular movement resulting in an incorrect torque being applied. I don't do this to crank main or rod bearing bolts/nuts or flywheel bolts, crank pulley nut, just those locations that use a gasket that crushes when installed. Or course I don't do this with torque-to-yield bolts! which afaik? were used on the last of the Spider twin-cam engines.
When I previously mentioned checking out the coolant frost/expansion/core plugs - I meant checking their surfaces inside the cyl. block (i.e. their back, unseen faces). They can appear fine on the outside and be just about to fail and they're a bit awkward to replace in situ. You don't mention if you've removed the coolant cover plate on the back of the cyl. block yet, or perhaps the engine stand is blocking access?
Please make ensure you at least give the crank oilways/drillings a really good wash and flush through if you don't want to risk removing the small (10mm?) oil drilling expansion plugs (you can see these on either? side of each rod journal of the crankshaft.
I appreciate the mention and the thanks
(but would, of course, prefer cash, or better still, gold
I'm going to investigate that crack (shudder) today... And have some new pics to share of the latest work on the cylinders.
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smahaley
Member
Some update photos: broken stud in the cylinder head! Don’t know why I waited so long to remove studs but one was loose - weirdly - and only had 2 rounds of threading holding it on, with the remainder broken off. In the image below it’s the one on the far right (still in the head) - exhaust side, #4 cylinder (which has had a rough time of it all around). I have a drill and a threaded extractor I’ll try. Also I reduced the edge of the helicoil on that cylinder with my Dremel, per advice.
Also: more honing on the cylinders and prepping for old pistons + new rings.
I put a #1 compression ring about 1.5 to 2 inches down just to see (on cylinder 3). My feeler said .019, whereas the Haynes calls for .013 to .017. Your thoughts on this ? Order slightly oversized rings ? I still have a bit of a ridge left so will work on those.
Finally - I checked the “crack” inside of the block by #4, and with my light found that each cylinder has a similar edge - some more noticeable - that appear to be from when it was cast. Whew!
Also: more honing on the cylinders and prepping for old pistons + new rings.
I put a #1 compression ring about 1.5 to 2 inches down just to see (on cylinder 3). My feeler said .019, whereas the Haynes calls for .013 to .017. Your thoughts on this ? Order slightly oversized rings ? I still have a bit of a ridge left so will work on those.
Finally - I checked the “crack” inside of the block by #4, and with my light found that each cylinder has a similar edge - some more noticeable - that appear to be from when it was cast. Whew!
There are still some big vertical score marks evident, one looks quite deep. The honing should result in a uniform x cross hatched pattern and ideally no score marks
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smahaley
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Yeah - more than one cylinder have the vertical scoring; I really think some fairly bad things happened internally to this poor motor. So you think I should just keep honing? I’m starting think slightly oversized rings might be needed…
I wouldn't try to remove the vertical scratch/es by continuing to hone, these scratch/es are unlikely to make any noticeable difference to the way the engine runs/performs (your engine is already running low compression pistons...).
Have you just been honing the top portion of the cylinder bores? you need to hone the full length of the cylinder - otherwise you're increasing the degree of taper wear present. I keep seeing the top of the cylinder honed and the lower portions still shiny as if not honed?
I wouldn't try to remove the wear lip evident near the top of the cyl. bores by continuing to hone either - I'd just try to blend out the upper lip so that my fingernail can no longer detect any step (this is important, if your nail can catch on the step, then so can the ring - not good, which is why I mentioned favoring the use of 'ridge-dodger' type rings in worn bores)- I'd use an old style curved Engineer's Scraper, but you could use your Dremel tool, seeing as you have one.
When finally you get to reassemble the engine, I'd suggest you position the top piston ring gap away from the wear ridge to prevent the new ring ends flexing in and out of the wear lip. The usual advice is to space the ring gaps at 120* apart, some suggest other spacing arrangements, some say the rings can rotate in use so it maybe doesn't matter but I'd position the top rings as described to give them the best start in life.
I wouldn't worry too much about the slightly larger ring gap you've measured. Was this using a new or old ring?
I measure ring gaps where the bore is smallest - either at the very top or at the bottom (i.e. where the rings don't traverse) - it's important that the ring gaps are not too small, I wouldn't worry about them being slightly larger than specified, remember this is for new or re-bored cylinders, not slightly worn ones. As the gap is being measured on the ring circumference, 3 thou too large corresponds to maybe 1 thou of diametrical bore wear, not worth worrying about. (again, is this with a new or old ring?).
I wouldn't recommend using oversize rings for 3 reasons - 1) you'll probably have to file all the ring gaps to suit your cyl. bores and the rings are easy to break while doing so (there used to be available a special fixture/tool that ground the ring end). 2) afaik, the curvature on oversize rings is very slightly different to that on standard size bores (slightly bigger circle = slightly different curvature), 3) you don't need them...
In case I forget to mention it, and this is for (much) later on, there is a 'break-in' procedure for engines where only new piston rings have been fitted i.e. cylinders not re-bored, + original pistons being used. I'll have to check the specifics but as far as I can recall, it involves starting the engine and running it quite fast for the first few minutes (c. 1500 - 2500 rpm), no idling being allowed. This correctly beds in the new rings.
And if you're using the original pistons, you don't have to do any other 'break-in' or gentle running-in - just get in and drive normally.
Likewise, if the crank journals haven't been ground undersize, you don't have to bed-in the crank bearings, although I would take it a little easy initially if new bearing shells have been fitted.
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