Technical Foreign Object Damage

[ronstox]

AndyRkett: The plan is to continue to tear down the engine and see what else needs to fixed or replaced. I'll follow Goldenrust's suggestions and see where it takes me. I like Bounding Bamino's suggestion of modestly upgrading to 540cc, but I'll first catalogue what needs to be done, then look at my options. I'll be back for advice and suggestions as I work through the engine.
j8rpi: Ethenol is mandated in several of the larger provinces in Canada, but out here on the east coast it appears that it is not. I called the Irving Oil a couple of years ago and they confirm that it is so. There are all sorts of new environment rules working their way through Nova Scotia legislature right now, so that may change. But for the moment, our gasoline is ethanol free.

 

[the hobbler]

AndyRkett: The plan is to continue to tear down the engine and see what else needs to fixed or replaced. I'll follow Goldenrust's suggestions and see where it takes me. I like Bounding Bamino's suggestion of modestly upgrading to 540cc, but I'll first catalogue what needs to be done, then look at my options. I'll be back for advice and suggestions as I work through the engine.
j8rpi: Ethenol is mandated in several of the larger provinces in Canada, but out here on the east coast it appears that it is not. I called the Irving Oil a couple of years ago and they confirm that it is so. There are all sorts of new environment rules working their way through Nova Scotia legislature right now, so that may change. But for the moment, our gasoline is ethanol free.

I would endorse Jacques (Bounding Bambino) suggestion----if you wish to retain your current engine (the original?) and don't want to go the "machine-shop" route, the '540cc'route is a sound one. It is a remove the old bits and fit the new job. If the crank is within tolerances, just clean the crank (internally as wellas externally) and fit new bearing. maybe fit a slightly warmer cam (35/75/75/35) and port the head, along with slightly larger inlet valves (increase original size by 2mm) but retain the exhaust. If you would like to contact me direct ( [email protected] ), I have put my thoughts regarding tuning the 500'sengine into an article---you are very welcome to a copy.

 

[ronstox]

I sent the head to a local engine shop for a good cleaning and to seat the new valves. They also skimmed 4 thou off the head to get it flat again. Here is the result.

 

[ronstox]

I have also ordered the 540cc piston & cylinder kit from Nanni Ricambi. They don't ship outside the EU, so I've sent it to a friend in Germany who will forward it on to me. It'll probably be another month or so before I see it.

 

[ronstox]

Christmas has come early! My 540cc kit from Nanni Ricambi has just arrived. Now I'll figure out how to bring the engine into my basement so i can work on it over the winter.

 

[ronstox]

I noticed that on the new cylinders there is a ring around the top that stands 1.5mm thick. As you see from my previous post the head is flat and my old cylinders are also flat. Hmmmmm.
Have I got the wrong part?
Will the head gasket compensate?

 

[bugsymike]

News Flash!
I found the FOD!
Following Bounding Bambino's suggestion, I ran a magnet around the head & pistons, and the stuff I'd cleaned up already and voila! It looks like a piece of piston ring.
Also, I found the old plugs. not sure which came from which cylinder though.

Looking at the top plug in photo , is the outer electrode missing, is that your foreign object due to the pre ignition?

 

[fiat500]

I noticed that on the new cylinders there is a ring around the top that stands 1.5mm thick. As you see from my previous post the head is flat and my old cylinders are also flat. Hmmmmm.
Have I got the wrong part?
Will the head gasket compensate?

That's odd.The standard 499 barrels when new had a machined groove that was bisected by an exit tapping that helps to route away toxic gases in the event of gasket failure. I'm sure that the ones supplied will work OK as barrels, but there is at least one other supplier that sells the 540 setup which includes that machined groove rather than a ridge.

 

[ronstox]

Looking at the top plug in photo , is the outer electrode missing, is that your foreign object due to the pre ignition?

No the outer electrode is there. it's just the way the shadow falls on it that makes it look missing. I'm pretty sure the FOD is a bit of ring.

 

[the hobbler]

I noticed that on the new cylinders there is a ring around the top that stands 1.5mm thick. As you see from my previous post the head is flat and my old cylinders are also flat. Hmmmmm.
Have I got the wrong part?
Will the head gasket compensate?

That is thr first time that I have actually seen a close-up of a '540' kit---What say you Jacques? I might be worthwhile putting pistons on the rods WITHOUT THE RINGS, putting the barrels in place, fitting the con-rods and pistons (but not torquing the big-end bolts) and see where the pistons come up to on TDC. An easy way to fit the new pistons onto the conrods is to fit 1 gudgeon pin (aka wrist pin) into the new piston, warm up the piston in a pan of boiling water, and the push the gudgeon pin in through the piston and con-rod right up to the circlip. Taking the old piston off is just the reverse of that proceedure. When fitting the new pistons (and NURAL are a good make) make sure that the gudgeon pin off-set is correct vis-a-vie the numbers on the conrods. The offset is only 2mm but it is AWAY from the numbers on the conrod---the numbers go TOWARDS the camshaft

 

[fiat500]

This image is from the Nanni Ricambi site and labelled 540cc; it also offers aspecially matching camshaft. Have you looked at the pistons to see if they match that image?

 

[Toshi 975]

Piston crowns and barrels from the Nanni 540cc engine I built. It was using a new old stock kit.

 

[ronstox]

Ok, here's what I ordered and what I got from Nanni Ricambi (https://www.fiat500sport.com/en/pro...ardiniera-piston-liner-kit-diam-70-mm-540-cc/) . This screenshot is not too clear but the website photo definitly shows the lip around the top. Here they call it a "Piston Liner Kit" which I didn't concern myself too much about when I ordered it because the photos looked like what I wanted.
I couldn't find the photo fiat500 posted above. What is the link to that?

 

[Bounding Bambino]

Looks like older versions of the cylinders had a full deck with the "gas" ring. I wouldnt be too concerned. The outer "lip" is not a sealing surface, the head gasket only seals on the inner raised edge.. My engine has the 540cc kit in it, iirc it had a date stamp on it from the mid 90's. It is the full deck style. To me, looks like they just changed the way the cylinders are machined.

The important bit would be. Like Tom mentioned is to temporarily Install the cylinders into the case, and pistons, and check the deck height/clearance. (piston at TDC, and measure the height of the top of the piston, to the height of the top of the lip. This measurement along with a head chamber CC measurement will be able to help calculate compression ratio. Also it helps to calculate squish.

This kit should be drop in and pre-machined ready to go. But it helps to double check, and we can help you with how to measure and calculate. IIRC i have the volumetric calculations for that piston style somewhere, which obviously helps with compression ratio calculations on a stepped piston.

I would strongly suggest you do a CC measurement on the head. That head of yours has been skimmed a few times, and imo would be good to try and keep compression ratios below 9.5:1 unless your ready to fiddle with timing, keep an eye on ping, and run high octane fuel.
All you would need is a Burette (amazon), and a scrap pc of plexiglass to do the measurement on the head.

 

[the hobbler]

Looks like older versions of the cylinders had a full deck with the "gas" ring. I wouldnt be too concerned. The outer "lip" is not a sealing surface, the head gasket only seals on the inner raised edge.. My engine has the 540cc kit in it, iirc it had a date stamp on it from the mid 90's. It is the full deck style. To me, looks like they just changed the way the cylinders are machined.

The important bit would be. Like Tom mentioned is to temporarily Install the cylinders into the case, and pistons, and check the deck height/clearance. (piston at TDC, and measure the height of the top of the piston, to the height of the top of the lip. This measurement along with a head chamber CC measurement will be able to help calculate compression ratio. Also it helps to calculate squish.

This kit should be drop in and pre-machined ready to go. But it helps to double check, and we can help you with how to measure and calculate. IIRC i have the volumetric calculations for that piston style somewhere, which obviously helps with compression ratio calculations on a stepped piston.

I would strongly suggest you do a CC measurement on the head. That head of yours has been skimmed a few times, and imo would be good to try and keep compression ratios below 9.5:1 unless your ready to fiddle with timing, keep an eye on ping, and run high octane fuel.
All you would need is a Burette (amazon), and a scrap pc of plexiglass to do the measurement on the head.

I have noticed that the information on the Nanni web-site picture advises you the the head is fitted back on WITHOUT headgasket! This is not an unusual way to re-fit a head---my '695' conversion also does away with a head gasket. There are adhesives that allow this proceedure---WELLSEAL is one such product which is highly recommended. I have used this product on both my '695' engine and a small marine diesel which had a capacity of 1500cc PER CYLINDER!---never sufferd a head-to-barrel leak This 'gasket goo' will allow fairly easy removal of the head at any later date. DO NOT use a 'permanant' adhesive.

 

[ronstox]

I have noticed that the information on the Nanni web-site picture advises you the the head is fitted back on WITHOUT headgasket! This is not an unusual way to re-fit a head---my '695' conversion also does away with a head gasket. There are adhesives that allow this proceedure---WELLSEAL is one such product which is highly recommended. I have used this product on both my '695' engine and a small marine diesel which had a capacity of 1500cc PER CYLINDER!---never sufferd a head-to-barrel leak This 'gasket goo' will allow fairly easy removal of the head at any later date. DO NOT use a 'permanant' adhesive.

Oh, I missed that bit about the no head gasket. The "lip" makes more sense now with a smear of "gasket goo"

 

[bugsymike]

I have noticed that the information on the Nanni web-site picture advises you the the head is fitted back on WITHOUT headgasket! This is not an unusual way to re-fit a head---my '695' conversion also does away with a head gasket. There are adhesives that allow this proceedure---WELLSEAL is one such product which is highly recommended. I have used this product on both my '695' engine and a small marine diesel which had a capacity of 1500cc PER CYLINDER!---never sufferd a head-to-barrel leak This 'gasket goo' will allow fairly easy removal of the head at any later date. DO NOT use a 'permanant' adhesive.

Around 1970 when racing Karts in Class1V Villiers we used to "lap" the head to the barrel and get a perfect seal with no gasket or even sealant, using a piece of plate glass and fine grinding paste.

 

[fiat500]

Ok, here's what I ordered and what I got from Nanni Ricambi (https://www.fiat500sport.com/en/pro...ardiniera-piston-liner-kit-diam-70-mm-540-cc/) . This screenshot is not too clear but the website photo definitly shows the lip around the top. Here they call it a "Piston Liner Kit" which I didn't concern myself too much about when I ordered it because the photos looked like what I wanted.
I couldn't find the photo fiat500 posted above. What is the link to that?

View attachment 434880

It looks like maybe I didn't find it on that site....I'll go back and work out where I got it from.

 

[ronstox]

I can't find any Wellseal in Nova Scotia, so I wrote to Nanni Ricambi to ask what sealant they recommend, and guess what, Nanni wrote that "nothing is required between the head and the cylinders!" I'm not sure I believe that. I also wrote to Permatex to ask them which of their products they recommend for this purpose, and they wrote back that none of their products are designed to be used without a gasket. Hmmm.
I measured the "lip" thickness at 7mm. That gives a mating surface area of about 44mm^2. That doesn't seem like much to me. Even with a sealant.

 

[bugsymike]

eBay listing for Stag Wellseal?
eBay item number:273740679575