I am in the process of tearing down my shelby 427FE to do a cam swap (see "Now thats a Cam" thread). It is going pretty much as I expected, just takes time but no real problems. I finished tearing it down tonight and got the cam out. When I pop'd the intake (shelby MR dual plane) I discovered that the intake gaskets (Fel-pro print-o seal 1247 for MR heads) had failed on three of the ports (#1, #5 and #8). See attached picture of #5 port. Each of them failed in the same way by tearing right at the edge of the port. Of the failures I know #1 was a vacuum leak as the intake port has
oil residue on it compared to the others. The others might have been leaking too. This was more then likely part of my idle and low vacuum problem I was chassing with my cam. Oh well I guess it was good I was tearing it down and found this.
My question is why did these gaskets fail? The engine was assembled by Carrol Shelby Ent. in '99 and has about 6K miles on it. Also because it has medium riser heads, the only gaskets I found were the Fel-pro 1247s the same that were on there. I guess I will have to keep an eye on them in the future and expect to replace them regularly.
One nice discovery is that I found out my shelby heads are fully ported (I thought they were as cast). Also the shelby rocker assembly is pretty trick looking and very stout. Working on this engine is very interesting because I get to see the insides and find out exactly what is there...