Carburetor Base Gasket

[David P.]

Re: Carburetor Base Gasket

Dave,
Based on John Hinckley's offering below only the 1970-72 Holleys had the thick gasket that makes this an issue, on the other hand one cannot have too much care in tightening the carburetor to the intake manifold. I don't think one can do any harm using this procedure on earlier Holley equipped vehicles.

Thanks Terry. I've actually never had my Q-Jet off my '70 454 and don't know what thickness/type of gasket is there, but I have taken note of this important issue. I realize the discussion is about Holleys, but I assume the potential for gasket damage transcends the carb type... Holley or Rochester.

[Timothy B.]

Re: Carburetor Base Gasket

Not trying to be difficult, but while AIM does state 14-18 FT/ lbs for carb to manifold on '67's, Holley service/rebuild book and carb restores such as Eric Jackson recommend 100 IN/lbs, -big difference, and many specifically warn against over tightening.Any explanation for differeces? What to do?

100 inlbs is approx 10 ftlbs so not much difference, I personally would stay on the light side of the torque range. Mine usually end up just beyond snug but the gaskets are thin, approx .060 I also use thin washers under the nuts because I don't want to damage a 600. carburetor, I love the way my Holley runs on my 67.

[Terry M.]

Re: Carburetor Base Gasket

Thanks Terry. I've actually never had my Q-Jet off my '70 454 and don't know what thickness/type of gasket is there, but I have taken note of this important issue. I realize the discussion is about Holleys, but I assume the potential for gasket damage transcends the carb type... Holley or Rochester.

There is no such notation on the 1968-72 AIMs for Rochesters that I am aware of. You might want to check the specified torque value for Rochesters. It wouldn't surprise me that it is different than Holleys, but beyond the ultimate torque value the diagonal and gradual tightening can not hurt and might even be an advantage. The thickness measurement given however is likely unique to Holleys, or at least bears verification before using on Rochesterrs. Note also that the rearmost fasteners on the Rochesters went from nuts to bolts in either 1969 or 1970 and that itself could change the ultimate torque specification for those fasteners. Be sure the torque value you find is appropriate for your type of fastener.

[David P.]

Re: Carburetor Base Gasket

Sage advice as always, Terry. Thanks.

[Joe L.]

Re: Carburetor Base Gasket

Thanks Terry. I've actually never had my Q-Jet off my '70 454 and don't know what thickness/type of gasket is there, but I have taken note of this important issue. I realize the discussion is about Holleys, but I assume the potential for gasket damage transcends the carb type... Holley or Rochester.

Dave------


For 1970 it depends on whether the car has RPO NA-9 (California-only), or not. For non-NA-9, the gasket was an open plenum-style, Q-Jet gasket about 1/16" to 3/32" thick. For NA-9 it was a similar gasket that was attached to an aluminum heat shield.

[David P.]

Re: Carburetor Base Gasket

Thanks Joe.

[William F.]

Re: Carburetor Base Gasket

Communicated with John Hinckley about this by e-mail. He actually just "snugs his carb to manifold by hand ." Don't think this would be anywhere near 16-18 ft./lbs. torque. Holley still recommends 60-80 in./lbs. Just don't want anyone to "hunker down" on nuts and warp their base plate.

[Mark D.]

Re: Carburetor Base Gasket

That 3247 is as rare as a good looking airline pilot. Big dollar carb, for sure.