Re: Carb issue
Thread Starter
Intermediate
Joined: Jul 2014
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Re: Carb issue
1979 Vette, L48 all tvs switches, Ca smog compliant. Boo! But she passes
Ok replaced carb due to bad air leak per mechanic. I installed the new carb with a new gasket and heat shield? Did not have one before. Auto store said I need one. How do I find out if I am supposed to have it or not. Sadly I hear air getting sucked in. I suspect it is the mating surface (damn heat shield) no matter what I am removing it but how do I find out if it was supposed to be there. Just curious is all.
Ok replaced carb due to bad air leak per mechanic. I installed the new carb with a new gasket and heat shield? Did not have one before. Auto store said I need one. How do I find out if I am supposed to have it or not. Sadly I hear air getting sucked in. I suspect it is the mating surface (damn heat shield) no matter what I am removing it but how do I find out if it was supposed to be there. Just curious is all.
Melting Slicks
Joined: Oct 2012
Posts: 2,156
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From: Dunedin NZ.
Okay so you replaced the carb due to a bad air leak and you say you still have an air leak, what does that have to do with fitting a heat shield? If your engine performed okay without one before chances are that it will again if you remove it but what about that darned air leak? I assume that you are talking about a leak at the manifold to carb join? did you check to see if the manifold itself was not warped? Did you put gaskets on both sides of the heat shield?
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I placed the metal carb gasket on the manifold. Then placed the Felpro gasket and topped it with the carb. Car runs stronger but I hear an air leak really loud. I swear is from the carb to manifold connection. Did not do that before. Funny old carb ran horrible, new carb, poor instillation and still runs better.
Team Owner
Joined: May 2001
Posts: 87,334
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From: Western NY
I placed the metal carb gasket on the manifold. Then placed the Felpro gasket and topped it with the carb. Car runs stronger but I hear an air leak really loud. I swear is from the carb to manifold connection. Did not do that before. Funny old carb ran horrible, new carb, poor instillation and still runs better.
Not sure what style you have, but if it's the "sandwich" type, you have to set it up such that a soft gasket is directly on the manifold, then a metal piece, then a soft gasket, etc, and you end up with a soft gasket against the base of the carb. Unless you have the parts in this order, you'll have a vacuum leak.
Secondly, and very importantly, you DO NOT torque the crap out of these gaskets, as you can easily either warp the carb's base, or worse yet, break off one of the mounting ears. Snug enough so it doesn't leak, is all you need....
Drifting
Joined: Feb 2005
Posts: 1,879
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From: Los Gatos CA
The sandwich gaskets are for the smiley face manifolds found on 67(?) to 69 Q-Jet manifolds. They are easily identifiable. If you swapped carbs and replaced gaskets, did the new and old gaskets match?
Tech Contributor
Joined: Aug 1999
Posts: 14,376
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From: At my Bar drinking and wrenching in Lafayette Colorado
You cannot use the 67-69 metal shield gaskets on a 79. It will result in a massive vacuum leak. Remove the incorrect shield and gaskets and install the correct 1979 1/4" thick thermal gasket that came stock on your car.
Lars
Lars
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Thank all of you for the info. I listened to the auto parts store on the gaskets. Bad idea. It was the 1/4 inch one I needed. Took care of the issue. She runs very well. Still kept my original carb for later.
Team Owner
Joined: May 2001
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From: Western NY
