I JUST received my refurbished carburetor 7026240
it is transmitted with 2 gaskets : one high-temp composite gasket and one stainless steel shield
i think that i have to put the composite gasket on the intake manifold then the stainless then the carburetor ...is it exact ?
I SAWN THIS fitting here https://www.corvetteforum.com/forums/c1-and-c2-corvettes/1978466-q-jet-carb-base-gasket-tech-info-the-hot-slot-manifold-problem.html
A common mistake when installing a Q-Jet on a 1966-1970 GM V8 is that the “mechanic” uses a 1971 – 1980 carb base gasket. This results in severe exhaust gas ingestion into the intake manifold, external exhaust leaks on the driver’s side of the carb base, and possible carb base damage and engine damage from detonation.
Early Rochester QuadraJet Carburetor installations (1966-1969) often used a “hot slot” exhaust groove that runs from side-to-side in the intake manifold just forward of the primary throttle bores, popularly known as the “smiley face” manifolds. The purpose of this “smiley face hot slot” was to run hot exhaust gasses under the carb to provide fuel pre-heat on cold days. The hot gasses would heat up a stainless steel plate, and the carb was bolted directly to this stainless plate for good heat transfer. Chevy used this design on ’66-’68 327/300hp, ’68 327/350hp, and ’66-’69 427/390hp Corvette engines, and Pontiac used it on their '67 4-barrel engines.
There are several problems with this arrangement:
1. A hot carb with hot fuel may run very well on cold mornings in Minnesota, but this arrangement does not run well on hot summer nights in Southern California.
2. A carb bolted directly to a steel shield is highly prone to vacuum leaks between the carb and the shield.
3. Any leak in the gasket arrangement results in exhaust gas ingestion directly into the intake manifold, which leads to poor engine performance and the possibility of engine damage if the leak becomes severe.
4. Since the “hot slot” was only used for a few years, there is a high probability of “mechanics” installing the incorrect carb base gasket (late model style), resulting in exhaust gas ingestion into the manifold and external exhaust leaks due to the incorrectly-fitting late-model base gasket.
To solve this problem, you need to use a special 3-piece carb base gasket “kit” for the “hot slot” manifolds. There are no parts stores who recognize the existence of such a gasket kit, so you have to create your own (I am no longer offering these for sale).
Here is a typical cast iron Chevy “hot slot” “smiley face” manifold. The slot was also used on the aluminum Chevy Big Block manifolds, ’66-’68 327, and on 1967 Pontiacs. The “hot slot” is the long groove running from side to side just forward of the small primary throttle bores.