Another carb base gasket question...

[Everett Ogilvie]

I want to be sure the carb. base gasket is correct on my '66 425 HP car so as not to damage the carb. What does the AIM show? The intake is aluminum without any exhaust grooves directly at the carb mounting surface, but does have the runner type exhaust crossover as most do. If the manifold surface directly under the carb is not heated directly through the use of a "groove", is the use of any stainless plate needed? I had heard not. And, if no plate is needed, what gasket: thin, or the thicker metal/composite type?

thanks, Everett

[Joe L.]

Re: Another carb base gasket question...

Everett----

Your 1966 425/427 does not use a carb "pre-heat" exhaust groove. It does, of course use the exhaust heat crossover since this is necessary for operation of the divorced choke. No stainless steel baffle is used or necessary for your application. The original gasket for your application, and all successor GM part numbers, have been discontinued. Reproduction gaskets are available from Dr. Rebuild under his part number 3726122. I have not seen Dr. Rebuild's offering but, usually, his gaskets are EXACT as to configuration and material.

Without the "pre-heat" groove, your carburetor is far less susceptible to heat damage even with the exhaust heat crossover. Of course, you could eliminate the exhaust heat crossover by installing intake manifold gaskets without exhaust heat crossover provisions. I don't recommend this, though, as you will lose operation of your choke and you will gain very little with respect to carb protection.

[Alex Gilmour]

Re: Another carb base gasket question...

Joe, Thanks for the tips on my '66. I looked around for a stock steel/composite gasket without the crossover passage. The closest one I could find was a Mr. Gasket piece that is pretty thick, but it isn't steel reinforced. I am going to put it on tonight, I will let you know how it works out. I would think that going to 1 thick gasket would tend to give me less problems than using the steel plate between the carb and the base gasket. That setup just seems like it would be more condusive to a vaccuum leak.

Thanks, Alex

'66 A/C Coupe