That manifold requires a HIGH TEMPERATURE gasket having an open channel to match the groove carved into the manifold ahead of the primaries. There'd be a heat shield on top of the gasket, directly under the carb. If the gaskets used aren't shaped properly, there's a huge air leak into the manifold. If the exhaust crossover and the heat channel are still operative, and the wrong gaskets are used, there's an exhaust leak into the manifold.
That's the little guard-tower for the choke linkage. Most Q-Jet cores are missing this piece (along with the front vent cover). I have a couple, and always have it assembled to the carb. It keeps the air cleaner base from bending/affecting the choke rod linkage during assembly.
Definitely I know I have the wrong gasket installed and never had a heat shield. Bought the car like this. So which is the proper high temperature gasket that I should be using? Would the one that was earlier recommended work? http://www.oldbuickparts.com/product_info.php?products_id=8059
I'm sorry we ran away with your thread! The deal is I think any gasket in that configuration should be a high heat type gasket. That's like an exhaust or EGR type gasket that's thicker with like small bits of metal in it that can withstand the heat, as opposed to a thin paper type gasket. Honestly, when I did my own it was years ago, NOS was available and both my gasket + shield were NOS. I remember what the gasket looked like, the shield I don't really remember. But I know there are some differences in the parts available now. That's why the gasket and shield I posted differ from the ones that John posted. I've never personally used that gasket from CARS. If you buy from the place that John posted, or Everyday Performance (Ken), they are both members and carb guys, so you know the parts are good. The CARS gasket is probably good, too. See what others say.......
My concern with the one that John posted is that it defeats the purpose of the proper gasket with the heat shield as it covers the front and middle groves on the manifold. Shouldn’t such groves match up with the carb? By adding such heat shield which is different from gasket would be like the current gasket that I have in there now.
The heat shield, the metal plate, goes up against the carb. The gasket goes on the manifold, then the shield, then the carb. Some say you should use an additional gasket on top of the plate because the carb surface may be uneven. The plate should block the bottom of the carb off. If you don't have the plate, then the groove in the carb becomes plugged up with crap. Because the exhaust would actually be running up into the carb, there's a lot of moisture in the exhaust and it plugs up the carb base. That's why the shield is there. It's just the heat you want to preheat the mixture. You really don't need the heat except in cold weather. That's why racing guys block the heat riser at the heads. That's also why I said yours may already be blocked at the heads. A cooler mixture produces more power. I see your point, though. Looking at it, it looks like your gasket would work. I think that's actually an Olds gasket. The differences between the right gasket sealing and the wrong gasket not sealing are tiny. It's the way your manifold has those heat riser holes outside the primaries, they like bulge out there. I'm not really a carb guy, but I know some stuff from many years of working on carbs!
There's a smiley-channel gasket which goes between the steel plate and the manifold. The quadrajetparts.com site has all of the pieces.
https://quadrajetparts.com/quadrajet-steel-shim-heat-shield-buick-1966-cadillac-1967-p-1114.html https://quadrajetparts.com/quadrajet-base-gasket-thick-buick-1966-p-98.html https://quadrajetparts.com/quadrajet-base-gasket-thick-cadillac-1967-p-104.html
Thanks Larry. Should I be using the four hole design or open design? Is it more of a testing both and see which one works best?
I really don't think it would make much of a difference. I would plug those holes in the intake. You certainly don't want carburetor heat in Florida. Better yet, if you ever take the intake off, plug it right at the head.
Plug them at the intake or on the carb? What is the best suggestion to plug them up? I am guessing this is probably why they went with the 1/4 thick rubber gasket it had on it before. With such 1/4 gasket I was able to adjust the fuel mixture screws just fine, but with the new thin gasket plus heat shield, adjustment does not work.
I would plug it at the head. If the car has a heat riser valve, I'd ditch that as well. I think you may still have a vacuum leak if the adjustment screws don't work.
Drove around last night and the smell of gas was intoxicating. This morning I removed the carb and as expected the new gasket, heat shield and intake manifold were flooded with gas. I decided to mount the old 1/4 gasket between the heat shield and carb to try adjusting the fuel mixture. Same issue where I closed them all the way and car does not even hesitate to turn off. I even drove with mixture screws closed for about 10 minutes. Came back home and checked for vacuum leak. Still present in front area of carb. Unfortunately I can t tell if vacuum leak is at base of carb or between carb housing and throttle plates as I see another gasket there. I'm going to start fresh with new pair of gasket and heat shield from quadrajet link above. I still question as to why the 1/4 gasket was used without heat shield when engine was rebuilt before my ownership. Maybe they were having such issue and decided for such gasket? I can say that mixture screws worked just fine with the 1/4 gasket and no heat shield.
How about ditching the iron intake and buying an Edelbrock Performer or B4B. You will get the generic quadrajet opening with the ability to run a Holley square bore carburetor as well. When you swap intakes, block the exhaust cross over passages in the heads. It will be much easier to seal and the intake will run cooler.
Thanks Larry. I will take this into consideration. Would the quadrajet work with such manifolds? Also do you know of any guidance or how to threads on how to block the exhaust cross over passages?
Do you mean "overwhelming"? Doesn't sound like a gasket problem. Sounds like a flooding-carburetor problem. Did you LOOK at the gasket where it contacts the carb? Any air-leakage paths, especially in front of the primary throttles? Does the gasket fit the carb correctly? Does not even hesitate = immediately Turn off = dies Does not even hesitate to turn off = dies immediately. This is what I'd expect if you shut off the fuel supply via closed idle mixture screws. Nothing wrong there. ??? AGAIN, check your gaskets for sealing. I expect you'll find a leak path somewhere around the exhaust channel in front of the primary throttles...although it could be other problems such as wiped-out throttle shaft bushings. Buy the CORRECT style gasket and heat shield. There's more than one kind. What you have is not the style I'm used to. Your heat shield What I'm used to from the Chevy world Note the different shapes of the two styles of heat shield. The gaskets would also be different. Do you have the correct carb for this application? I can imagine a manifold needing one variety of gasket and heat shield, and a carburetor that needs a different design.
Here are the answers to all your questions: 1. The gas smell was strong and got to a point that driving was just uncomfortable from the fumes. 2. As for flooding, if the mixture is off or there is a vacuum leak, wouldn't it cause the carb to pump more gas causing the flooding carb problem? 3. I did look at gasket where it contacts the carb. As I sprayed carb cleaner to the front, you can hear the increase in rpm's telling me there was a vacuum leak. The gasket fits the carb just fine. 4. When the idle mixture screws are screwed in all the way, the car does not shut off. If I turn them out, the same thing. It is acting as if they are not doing anything at all. 5. When I turned in the screws all the way, I went ahead and drove the car and it drove just fine. 6. As for the gaskets, I purchased these from oldbuick parts with the smiley face in them: http://www.oldbuickparts.com/product_info.php?cPath=97_102_103&products_id=8075 http://www.oldbuickparts.com/product_info.php?products_id=8059 I will try the ones from quadrajet parts and see if it corrects the issue. 7. As for the correct carb, I am not sure. This is the one that came with the car when it was purchased. Thanks again for all feedback and additional information/questions. Happy 4th to all.
