I was chatting to another 500 geek about his F
He tells me it had a rebore, which I thought meant it was bored out to larger capacity granting more power however he doesn’t feel it

This is the invoice that came with he car when he bought it

In the parts supplied list it has “piston and ring set .6 O/size”

I ponder if this means it was bored to 600cc but perhaps a more learned member is able to quickly decipher the invoice and above part? Very curious!

Very small rebore to repair / remove damage. You won't feel any increase in performance.

The rebore will be to restore the cylinders to "as new" condition and not to increase the engine capacity. With that oversize without doing the maths it has probably added about 7cc to the original 499cc so he now has a Fiat 506
You can buy a 540cc kit that will fit straight onto a 499cc engine and that is the largest capacity you can go to without having to bore out the crankcase which is necessary if going to 600 or 650cc.

As David (Toshi) mentioned, any bigger barrels than the "540cc" kit will involve having the crank-case barrel apertures opened up to accept the bigger barrels--but be careful. On a 500 (110 and 120 engines) crankcase, it is NOT recommended that you go any bigger than 652cc, as enlarging the barrel apertures to take any bigger barrels will remove the 'sealing-lip' on top of the crank-case that is required for the seal between the barrels and the crank-case to sit on.

Thanks crew! Great info to add to my tiny bits of knowledge of these cars - a fiat 506 then

BambinoClassic said:

I was chatting to another 500 geek about his F
He tells me it had a rebore, which I thought meant it was bored out to larger capacity granting more power however he doesn’t feel it

This is the invoice that came with he car when he bought it

In the parts supplied list it has “piston and ring set .6 O/size”

I ponder if this means it was bored to 600cc but perhaps a more learned member is able to quickly decipher the invoice and above part? Very curious!

Click to expand...

That's exactly the size my 500 engine was rebored to when it had scoring from long term seizure.
There's nothing wrong with what was done on that engine..it all sounds very logical, except for one contradiction. Normally you would rebore the barrels on your existing engine, buying new pistons to fit. Some might argue that nowadays it would be more economical to buy a brand new, matched set of pistons and barrels and scrap the old ones; in that case it would give the option for a 540cc kit.
But the idea of the engine remanufacturer supplying secondhand barrels which then needed boring out in addition to fitting new pistons seems unnecessary. Presumably the engine's originals were damaged beyond redemption and your friend and/or the workshop were unaware how abundant the supply of new spares actually is?

Curious… It was all done prior to them owning it and overseas, so I wonder if supplies were just not as available then. I think it was at least 10 years ago… Or else perhaps the shop happen to have a set of barrels on hand that they just gave to them, who knows?!