Here to help . . .
Join Date: May 2010
Location: United Kingdom
Yep, you've found the danger of getting head gaskets from most auto centres.
There are two basic types, which we can classify as thick and thin. The metal layered gasket, as used on the later engines, is the thinner type.
The switch over date seems to vary on engine and model type so I won't quote any given figures for this sadly. I have seen either type on many varied ages and models, so it seems a little hit-and-miss despite the exact date being given by Alfa - well that's my experience anyway.
Therefore, if you install a thin gasket on an early engine, or have even had the head skimmed, it is recommended to use the thicket earlier type. I know of plenty of Alfa mechanics who just use the thicker type on all engines with no problems.
Personally, I simply check what gasket came off the engine, but if there is any confusion, like an unknown sourced block or head, then I use the thicker one to keep on the side of caution. I too have never had a problem with this method.
I did once get an engine that someone had installed the wrong gasket on and then sold on quick. At idle it seemed not too bad, but as you revved it, you could hear all the pistons hitting the head. You could also feel a resistance as you tried to get any of the pistons to TDC.
As you would expect it needed the pistons and head checking fully for damage, a set of new big ends and a thicker gasket and all was well again.
If it helps, EuroCarParts seem the cheapest source for Alfa headgaskets. They do the earlier thicker style (from memory its pn# 366510021) for around £12-14 if you have a good trade account with them.
Hope that helps you in the future.
*Removed by OA*