Technical 350A1000 cyl head max distortion

[rosssavage]

Hi folks, newbie 1st post.. Working on a friends Doblo with the 1.4 8v engine (350A1000). Cyl head gasket gave up and dumped coolant into #1, and almost no compression #3 (50psi or so). Looking at the head, there is damage to the #1 intake valve too, so we've gone for a used replacement head.

The new head has a low spot at the #4 end, measured at 0.06mm.

Does anyone know the maximum distortion limit please? It seems generically an ali head should be within 0.05mm (D'oh!) but I wonder what the specifics are for this head? Be a real shame to have to take it to the island's only machine shop for the sake of 0.01mm (we live on Corfu)....

 

[varesecrazy]

Hi

For comparison

What are the figures for the old head?

Only FIRE head I ever clocked (having lost a HG twice in 6 weeks) was in that order don't know a figure @8 years ago

So I reused it an had no issues (failed Heater Matrix losing coolant was "the smoking gun"..)

Are you using a straight edge and feelers, or an actual D. T. I.?


Maybe member @bugsymike has the data for your Doblo motor?

 

[rosssavage]

Hi

For comparison

What are the figures for the old head?

Only FIRE head I ever clocked (having lost a HG twice in 6 weeks) was in that order don't know a figure @8 years ago

So I reused it an had no issues (failed Heater Matrix losing coolant was "the smoking gun"..)

Are you using a straight edge and feelers, or an actual D. T. I.?


Maybe member @bugsymike has the data for your Doblo motor?

Thanks for the quick reply.

Unfortunately I don't have the old head to hand..

Using the straight edge and feeler method, which I know isn't the best. I do have access to a DTI, but I've not used one before. Any quick tips on how to set it up and I can measure again?

Thanks again!

 

[bugsymike]

Hi

For comparison

What are the figures for the old head?

Only FIRE head I ever clocked (having lost a HG twice in 6 weeks) was in that order don't know a figure @8 years ago

So I reused it an had no issues (failed Heater Matrix losing coolant was "the smoking gun"..)

Are you using a straight edge and feelers, or an actual D. T. I.?


Maybe member @bugsymike has the data for your Doblo motor?

I don't have specific data, but using a good straight edge and feeler gauges, personally assuming my conversion of .05mm to inches is correct @ just under 2 thousands of an inch I wouldn't be entirely happy.
Sorry I was brought up pre decimal/metric system.
I would test the cylinder block and any head going on the engine, using the straight edge and feeler gauge method, in all directions, so with the smallest feeler gauge I had, which would I think have been 1.5 thousands of an inch (0.0015 thou of an inch?), if it started to drag the straight edge I would want to correct it.
By the way I always clean out the thread holes and ensure head bolts go all the way easily, so when torqued correctly on a flat head and block with a good make of head gasket I knew there would be no CBJs, something we used to joke about regarding poor mechanics, Come Back Jobs.
If you feel it is only a small amount you may with a large sheet of plate glass and some lubricated fine grinding paste along with a bit of effort, correct it with an aluminium cylinder head, if cast iron cylinder block is distorted and I have seen that, then it is a machine shop job and a total strip down.

 

[bugsymike]

Another small point worth checking is the cause of the overheating in the first place, head gaskets don't just fail with old age.

 

[varesecrazy]

I had access to a milling machine

Dti in the chuck (stationary..) , wind from corner to corner looking for deviation
not having any reference data, I was looking for obvious Distortion, (Dips and Troughs) just saw gradual deflection, so was happy


You could probably do this on a hobbyist machine.

Or Even a Surface table with a bit of time..

I have a method for torquing doe the head that has served me well, ask when the time comes

 

[rosssavage]

I had access to a milling machine

Dti in the chuck (stationary..) , wind from corner to corner looking for deviation
not having any reference data, I was looking for obvious Distortion, (Dips and Troughs) just saw gradual deflection, so was happy


You could probably do this on a hobbyist machine.

Or Even a Surface table with a bit of time..

I have a method for torquing doe the head that has served me well, ask when the time comes

I have a wooden workbench and a pillar drill, so I feel I may be lacking somewhat in the machining department!

Torquing the head - I've read 22lbft +90deg +90deg in the correct order obviously?

 

[rosssavage]

I don't have specific data, but using a good straight edge and feeler gauges, personally assuming my conversion of .05mm to inches is correct @ just under 2 thousands of an inch I wouldn't be entirely happy.
Sorry I was brought up pre decimal/metric system.
I would test the cylinder block and any head going on the engine, using the straight edge and feeler gauge method, in all directions, so with the smallest feeler gauge I had, which would I think have been 1.5 thousands of an inch (0.0015 thou of an inch?), if it started to drag the straight edge I would want to correct it.
By the way I always clean out the thread holes and ensure head bolts go all the way easily, so when torqued correctly on a flat head and block with a good make of head gasket I knew there would be no CBJs, something we used to joke about regarding poor mechanics, Come Back Jobs.
If you feel it is only a small amount you may with a large sheet of plate glass and some lubricated fine grinding paste along with a bit of effort, correct it with an aluminium cylinder head, if cast iron cylinder block is distorted and I have seen that, then it is a machine shop job and a total strip down.

Thanks bugsymike. Ref bolt holes - yup, fine syringe to suck out oil, followed by compressed air and run the old bolts in and out a few times and another blow with the air. I don't have a tap of the correct size to truly clean the threads. I have new bolts for reassembly.

Unfortunately my thinnest feeler is .002" (.05mm) which is what I'm using. Got just the tiniest bit of looseness in one area which disappears at .0024" (.06mm)

 

[varesecrazy]

Ok.. Approaching this differently..

What did your straight edge make of the block?

Is that Really Flat and True... ?

IF you are confident in that as FLAT AND TRUE

Why not remove the dowels and

1, put the head on in its natural position (check around for gaps with the feeler)

2, rotate head - so cam wheel is over gearbox (180 degrees out, then use feelers again)

Should highlight what is likely to be True and Flat

 

[bugsymike]

Re thread taps, what I often do is run an old head bolt up a grind stone wheel in three flutes so it ressembles a tap , clean any rough edges on a wire brush and it works fine to clean the thread holes in the engine block.
Does this data compare with yours, it's from a 2012 AutoData Manual?

 

[rosssavage]

Re thread taps, what I often do is run an old head bolt up a grind stone wheel in three flutes so it ressembles a tap , clean any rough edges on a wire brush and it works fine to clean the thread holes in the engine block.
Does this data compare with yours, it's from a 2012 AutoData Manual?

Ah, superb! Thank you - next question would have been torque values Hopefully I'll get back onto it this afternoon so will report back. Thanks for your help so far..

 

[rosssavage]

Well a lesson learnt and a turn up for the books... Rechecked the cyl head today to find the distortion had moved to the #1 end. Much confusion and head scratching, re-cleaning and checking again - this time back to #4. Wtf??

Can you guess yet? My straight edge isn't.

I have a Rabone steel rule that I wasn't using, as it isn't long enough to span the whole head in one go. Instead I used the straight edge from a square I have that is long enough, but apparently not straight enough!!

So now I have both a head and block deck with immeasurable defects (at 0.05mm, my smallest feeler) and I am very happy. And a bit wiser....

Working tomorrow but may have time to start the rebuild tomorrow afternoon.

Thanks all again..