Quadrajet Gaskets

[chief poncho]

So, I just learned the hard way that there are numerous types of quadrajet gaskets. And more importantly, a base gasket designed for a Chevy, doesn't work with a Pontiac, even if it happened to be the carb gasket provided in two separate pontiac v8 gasket kits.  I've been chasing an issue with getting my car to idle correctly since recently getting it running.  I have a early '71 ish carburetor (I say '71 ish because I don't know if its a franken carb or not but it is not an HO carb).  It was built by a local guy.  The engine seemed to run pretty well, but I was having issues trying to adjust the idle mixture.  Rotating the idle screws wasn't making much difference.  Also, when I'd drop it into gear it would stall unless the idle was up around 1100 RPM.  Hooking up a vacuum gauge also showed pretty low vacuum, around 12", granted I have a decent sized roller cam in the engine 236/242 @.050.  Adjusting the idle screws made no difference in vacuum and little in idle.  So I started looking for a vacuum leak and found using some starter fluid that the front of the carb had a bad leak.

So a little more information.  I installed a phenolic 1/4" spacer between the stock 455HO aluminum intake and the carb that was supposed to be designed for Pontiac V8 applications.  Turns out it is, but only early Qjets, not '71's.  With a '71 plus Qjet, it doesn't cover some of the idle circuit ports cut into the base plate on the front of the carb.  So I had a leak with that setup.  I removed the phenolic spacer and just went with a gasket directly to the intake manifold.  Like I said, the gasket came right out of the Pontiac V8 kit.  Well it was a Chevy gasket and left a huge opening since one of the cutouts in the gasket up front hung over the intake manifold base.  Anyway, correct gaskets ordered.  It'll be interesting to see if it make much difference on how it idles. 

Phenolic spacer I ordered appears not to work for some quadrajet applications (doesn't cover channels/ports in front of primaries in base of carb):


Chevy Gasket that was in gasket kit (note cutout in front of primaries - No Bueno for Aluminum HO Intake but apparently correct for '67 Pontiac V8):


Correct Pontiac '68 to '74 Qjet Gasket....I hope???

[firebirdparts]

Thanks for posting that.  I guess I'm not surprised.

[chief poncho]

So I was looking through Rocky Rotella's Pontiac Engine book and on page 25 I notice a picture of an intake in there that looks like it would accept the gasket that I identified as a "chevy" gasket.  I don't know what year the engine is, but it looks to be out of a 67 GTO.  So it may be correct for some Pontiac applications after all, but certainly not for a '71 HO intake. 

Edit:  A quick look in my Ames Performance catalog and it shows the gasket with the cutout in the front being applicable for '67 Pontiac V8s.  I wonder if it was a one year only gasket, but also may be applicable for some Chevy applications. 

[chief poncho]

New gasket arrived today and it fits perfectly.  Fel Pro number 60061-1 for 68-74 Pontiac V8.  Also says it fits Ford products.  I haven't installed it and tried starting the car yet.  I'll update this thread when I do.

[gstrandfarm9420]

One person to call if you 're still having issues is Sean at SMI Carbs In Long Beach CA, he fully understands every aspect of the Quadrajet series. I sent a smog era carb to him , told him what I had and he built it to match. Almost like fuel injection, except you still have to give it a few pumps when cold starting to set the choke. This was a few years ago, but I think he is still in business.