Hey guys. Going nuts trying to figure this out. Here it goes.
I have a 71 LS5 454 w/ stock intake 3955287 Q-jet intake. New Holley 4165 spread bore/Q-jet replacement on it.
Of the sources:
Holley carb directions
Holley tech line
Holley Book by Mike Urich and Bill Fisher
Numerous Corvette forums/topics w/ pics
All offer different takes on carb gaskets, how to stack, what to use.
I have an exhaust crossover up front but primaries, but can't find the correct gasket
Holley directions with carb insists on using the and exhaust/header type think gasket and thin metal shim, then carb (in that order).
Holley tech line says to put down thin metal shim first, then gasket and carb.
I even bought the the insulated .25 Q-jet style Holley 108-25 with plastic "o" rings around studs.
I bought two thin metal shims (Holley 108-20), but they are different than my intake style. Comparing it to other BBC intakes in my garage, they match ('68).
Using the exhaust header-like carb gasket included in carb kit leaves room for an exhaust leak.
Nowhere can I find an exhaust-material carb gasket and corresponding shim for my car (though the shim I have will probably work).
Here's 3 pics:
1st, stock intake flange; Second, with the '69 style exhaust-material gasket that would leak (see finger pointing); and 3rd, with the .25 phenelic Holley spacer (I've been using).