Looking for input from experienced engine builders.
In the August '08 issue of Chevy High Performance magazine, there's a discussion about Fel-Pro head gaskets:
Quote: "When replacing head gaskets in the L98 aluminum -headed engines and the ZZ small block family engines, you must be very careful. The Fel-Pro head gasket has a diameter of 4.166 inches. This large diameter gets very close to the water jacket feed on the spark plug side of the cylinder head deck. With this gasket, you have less than 0.050 inch of sealing surface. It's very easy to knock the gasket out in this area. This is why we recommend sticking to factory head gaskets that have a diameter of 4.100 inches. The production gaskets are 0.052 inch thick for the aluminum heads, and 0.026 inch thick for the iron heads. I use the 0.026-inch-thick gasket exclusively for my performance street buildups. Most of the GM short-blocks have the pistons somewhere around 0.020 down in the hole. The iron gasket at least gets you in the ballpark for a decent quench."
They mention it again in the Sept. '08 issue.
Quote: " As for performance head gaskets, Fel-Pro's very popular 1003 and 1010 head gaskets are built to a gasket diameter of 4.166 inches. As you can see, this is well over the bore size at the largest 350 overbore. I really prefer to use the smaller-bore size gaskets because this larger gasket allows spent exhaust gases and carbon to live in this crevasse. During the exhaust stroke, there is no real way to evacuate this area, and the remaining spent combustion gases can mix with the incoming charge and reduce the power potential."
Anyone have any thoughts on this?

 

Seems to me you have hit the nail on the head already. I totally agree w/you.

rk

 

Bore diameter differences is a consideration I do not recall seeing
discussed before in the threads about L98 head gasket failures but
the FelPro 1010 certainly has a dismal record with CF members.

In looking into the matter, I came across information that indicated
that the 1010 was constructed with a copper fire ring and proposed
that galvanic corrosion between dissimilar metals might be a
contributing factor. Information about the FelPro 1003 indicated it
was constructed with a steel fire ring and galvanically, steel is a
closer match for an iron block/aluminum head combination. In
checking a post about AFR's recommendation, it was shown that
they specified the 1003, not the 1010 for 350 displacements. In
looking back at earlier threads, FelPro was said to recommend a
7733PT2 over the 1010.

Thoughts and links posted previously, such as here:
Update on Blown head gaskets

Both the 1010 (0.041") and 1003 (0.039") have an advertised
compressed thickness of less than the stated production 0.052".

Regarding the 7733PT2. Before blindly buying & installing this part,
hold it up to a head to inspect for intrusion into the chamber to
verify it is suitable for the heads.

.

 

Good info - but the stock head gaskets (allmost always at #7) had an incredible failure rate which at one time generated a spate of complaints at www.nhtsa.gov, several lawsuits and finally a Service Bulletin with a redesign of the forward and aft intake mounting bolt holes. GM's engineers concluded that galvanic corrosion was the culprit and the likely cause was misalignment of the intake gaskets which resulted in intake leaks. The intake bolt holes were redesigned to accept gasket retainers which allowed for perfect alignment of the intake gaskets. That design remains in place today and is used on the 113's bolted to the ZZ4's or available as replacement heads. Unfortunately, and even though the design change was identified in a Bulletin issued in November of '89, the only L98 to receive the change was the '91 or last year. And Vette intake Gaskets for that Year are incredibility hard to come by though using the F-Body or ZZ4 intake - without the coolant restrictors - doesn't seem to cause any problems. It does seem evident, at least around here, that the '91 doesn't suffer from the same head gasket failures as the earlier 113's - nor do the earlier aluminum heads (128's?) for reasons I've never been quite able to determine.

 

The FPP-1094 is also thinner and 4.100.

 

How did I know....after reading the heading......that one of my old threads would show up here about my 1010 disasters.....albeit the high compression ratio blew mine out. so far so good with the 1003's.