Franko500 said:

I checked the size they are 67.4mm diameter, so standard size but yes they look like the early tuning ones that I think The hobbler mentioned a while ago. So really hope I can save them. Only problem being if I can reuse the cylinders as the later cylinders have the recess and use a different gasket so not sure if they are interchangeable.

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Actually it was #Toshi975 who posted the modified pistons
http://www.fiatforum.om/500-classic/440875-abarth-pistons-barrels-2.html

Franko500 said:

I checked the size they are 67.4mm diameter, so standard size but yes they look like the early tuning ones that I think The hobbler mentioned a while ago. So really hope I can save them. Only problem being if I can reuse the cylinders as the later cylinders have the recess and use a different gasket so not sure if they are interchangeable.

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hello Franko500,

now I know what you mean with "recess" (my english is not so good).

ok: the gaskets are interchangeable, there are no differences beween gaskets of D- and F-type engines.
As you absolutely correctly mentioned that recess was later added for leading exhaust gas to that hollow screw if the head gasket was broken. The D-type engine didn't have that. No problem for the gasket.

So if I can save the Pistons but need new cylinders, I could use the cylinders from my L & use the original D head?

Franko500 said:

Ian, when I get a minute I will remove my L clutch plate and take a photo of the flywheels and differences.
From what I can see the D has a lighter flywheel and is thinner.
The L looks to be a different profile and heavier than the D but looks lighter than the 126.

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The 500D flywheel has different teeth (less than the 500F and 500L) and even less than the 500R/126.
So for a D flywheel you need a 500D starter.

Franko500 said:

So if I can save the Pistons but need new cylinders, I could use the cylinders from my L & use the original D head?

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yes, of course. 500D and 500F/L have 499ccm and absolutely the same bore diameter. I hope you can safe those pistons. But you first should try new piston rings if they fit.

But tell me: why would you use new cylinders? are they damaged?

I have only managed to remove one piston as there is corrosion in the cylinder and the other one won't move. So they may need machining to remove the damage to the bore wall. This will mean the Pistons will be too small. So I will need to fit different Pistons or fit different cylinders so I can use the original Pistons.

I have a pair of 500 barrels if they are required (came plonked on top of the pistons on the 595 engine I have). they will need a good honeing, or possibly a bore-out to the next piston size.

Sean, I have been known to have a leaning towards retaining old bits of a car. But I would cut my losses on that one and just get a new set of matched pistons and barrels, possibly even a cheeky set of those 540cc ones.
From my experience with the corrosion-seized ones on my 500, yours will need boring. So the pistons won't fit even in the unlikely event of them being OK. Mind you, I also decided the original Fiat quality was likely to better so in my case I had the barrels rebored to fit the next sized but one pistons. It cost me nearly as much in the end.:bang:
KNO_6358 by Peter Thompson, on Flickr

the hobbler said:

I have a pair of 500 barrels if they are required (came plonked on top of the pistons on the 595 engine I have). they will need a good honeing, or possibly a bore-out to the next piston size.

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Thanks for the offer. Hopefully I will be ok.
I have got one piston out and the bore looks to be ok and should just need a hone.
The other one is causing a few problems and wont budge. So its in soak at the moment. Then I might try the ATF, petrol and rag in the bore, set it alight and see if that does it. Otherwise I will take it to the machine shop and they will put it in their hot acid to see if it moves. Going by the other one I think the engine had been sitting for a long while and the rings had just dried up with a funny old gundge around them.
Alternatively I may try my 500L pistons & pots. I need to strip that engine as I will probably be using the crankshaft if its the same.

So anyone got any bright ideas how to get this piston out?
Tried hitting with a block of wood and hammer.
Difficult with the cylinder off the block! but cant run the risk of damaging a D block. Also with the unusual shaped crown I'm concerned on hitting it too hard as I don't want to damage it.
Tried soaking in penetration oil.
Placed penetrating oil and petrol in bore, set fire, heated cylinder still no movement.
Turned it upside down and left with oil and petrol in the inside of the piston to hopefully penetrate the rings via the oil holes in the piston ring slots.
Nothing come out the other side.
I have now left it to soak with white vinegar as that usually helps break down all sorts of stuff.
I really want to get this piston out!

Stick it in the oven......?

what about using a water jet, like those on the carwash? it's not strong ehough to cut through, but might move the crap that's holding them together..

Franko500 said:

So anyone got any bright ideas how to get this piston out?

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I think either by rapid heavy impact or a hydraulic press.
The ones we used to use in the workshop would move anything, often with a sudden worrying but controlled "crack!!!" Most workshops will have different sized mandrels to spread the load.
If you could find an outer race from a suitably-sized wheel-bearing that fits nicely on the piston top, then had a thick steel disc on top of that, you could give it a fair wack, supported in a heavy vice.
I have a really heavy impact drill, a bit like a Kango, that can operate without rotating, it goes through concrete with ease...it's the weight. Hammer one of those on top of the protected piston and it would move in seconds.

AndrewHarvey said:

Stick it in the oven......?

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I would second that...
you could even put some oil on top of the piston as well so as everything heats up and expands the oil soaks through..

or
as alloy expands greater than cast Iron...
you could try lowering the temp of the piston when everything is hot by some cooler oil...

Problem is the shape of the piston crown is not flat. Check the photos.
Also difficult to support the cylinder without damaging. Already broken 2 fins of the casing!

I have played this game before.

There is no magical solution. If you heat and cool the cylinder barrel a few times, that sometimes breaks the bond between the piston, rings and barrel. Don't get it red hot as you don't want to damage the piston, maybe 150-200 deg C? I usually use a heat gun rather than gas as I find it a bit more gentle even if it takes longer.

And drown it in penetrating oil when it is hot. WD40 or similar seems to work ok. I use this Mouse Milk.
Mouse Milk Penetrating Oil - Power Tool Lubricants - Amazon.com.
It is a product we get at work sometimes and I wouldn't drink it, but it is the best I have found.

If all else fails then a judicious application of violence may be the only way. Remember the Mechanic's Motto.... "Don't force it, use a bigger hammer"

I hope this helps.
Chris

Thinking about it, what I actually did with mine was very low-tech and I totally agree with Looigi on heat and then quench with any kind of penetrating oil.
I used a short chunk of high strength structural timber, trimmed to square so it fit down the barrel, stuck the barrel on the jaws of the vice (it's a big 'un) and wacked the timber with a 4lb lump hammer....quite a few times. I didn't need to save the piston but I don't recall that I wrecked it. the barrel was rebored and is in my car now. Good luck.

PS, You could hollow out the end of the timber for the domed top...how domed is it?

Sean, you're handy, you could make this (move on a couple of minutes in the vid).
[ame]https://youtu.be/II91SvAtQ0c[/ame]

I am glad to say that the other piston is now out!
I have heated, cooled, hit it, soaked it in oil, petrol, White Vinegar, Rust eater and WD40 and set it on fire!
Eventually I had to mount the cylinder in the largest vice I could find clamped around the lower section. This was risking damaging the machined face that sits on the block but it was the only way I could hold it still.
I then shaped a piece of wood to fit in the bore with a rough shape of the piston to spread the load. Whacked it as hard as I could with a large hammer a number of times and it moved!
Finally got it out to find that all the rings were rock solid in their grooves. They were completely packed tight with carbon etc.
I managed to remove the rings - broke a few getting them out and then cleaned the grooves out with a small screwdriver and part of the broken ring as this removes the crud and cleans it completely out to the point that the ring fits the groove again.
The oil control rings were solid. I'm surprised any oil got through to the rings from inside the piston. The pistons have cleaned up fairly well.
There's some slight pitting from corrosion on one of the pistons but I think it will be ok.
The Cylinders are both slightly damaged from the rings/corrosion. There is also a slight lip at the top of the cylinder although I am thinking this is from the original pistons as the top ring on the high compression piston doesn't go up this high.
Next step give everything a quick clean then take it to the machine shop to get them to put everything in their cleaning tank and then check and diagnose if these components can be used again.
I might strip the 500L engine and see what condition the crank and cylinders are as I could possibly use these.
Does anyone know if a 126 crankshaft is the same as a 500D?

Job well done. i can see why you want to keep those pistons; they do look quite special.

I finally got back in the garage today for a few hours.
Decided to strip my 1971 500L engine apart to see if I can use the crank and cylinders.
Oh dear!
It all came apart nice and easy. a couple of surprises though!
There was a 6mm diameter washer in one of the cam followers. Not sure what damage that has done yet until I clean the components. Don't even know where it came from as I don't recall one being used on the engine.
I removed the big end bearing caps to find one of the bearings had some of its bearing face missing. And yet the crank journal appeared perfectly ok with no signs of damage to the other half of the bearing either.
The front main journal appeared a little on the rough side although the bearing appeared ok with just a few minor marks around the diameter. I might get the machine shop to check it and polish it if its ok.
Then came the pistons. Now I was expecting 67.4mm. Oh no, appears that the bores are approximately 70mm diameter and another set of high crown pistons. The pistons look good but sadly the bores have scores going up one side and the piston ring was broken. So I think these cylinders are finished. But maybe I could have my D cylinders bored out to use these pistons instead.
Has anyone any suggestions as to what they are and what cc this will make it?
Oh and has anyone got any good methods of cleaning engine blocks and components i.e. leaving them to soak in anything?