So I've stripped the heads off the 748 and found this.... looks like a bit if piston ring has come away as it was still embedded in the head. What would cause this. Also what's the pros and cons of getting the head machined or should I just replace it?
Why has someone stamped 'A' & 'S' into the piston? Does look a bit sloppy, has it been overbored? Head could be recovered if the divots are not too deep and the seats have not suffered damage by the bits of ring exiting the exhaust port. What ring broke first/second or oil control?
A&S are Italian for Aspiro and Sortio or something like that and usually show inlet and exhaust side of the piston. Look a bit odd 90 degrees apart but I ain't seen too many to judge. Unless you're really worried I'd just flat the worst of the head with some emery paper and stick a new piston and rings in. Check the bore though for damage too.
If it is a stock 748 it should be easy enough to pick up a secondhand head. If it's the later model 748E then you may have a stepped head, which is on one cylinder only and which might be harder to find but the engine was used in a different model, can't remember which one, so they may also be usable. The A and the S markings seem to have been done by someone who has had the head off. The "A" seems to be in the wrong place and should be opposite the "S". It looks like someone has marked them with a punch instead of stamping or engraving them as the factory would. My 1997 748 engine just had "S" marked on the pistons when I took the heads off but no "A" and it was stamped.
