Re: Internal vaccuum leak on 1973 Camaro?
Serious vacuum leak. Be aware, there are quite a few different carb to manifold gaskets for different applications of various carbs. All depend on correct carb pad sizing on the manifold, and the carb used.
In the case of a Q-Jet manifold, there are at least 7 different gaskets, all will cause leaks IF the wrong one is used.
On a Q-Jet manifold, with a square flange carb, there are a few different situations that can cause problems, like the bores in the manifold too large to seal the square flange carb. Edelbrock has a fix for the more mundane interface options, their adapter plate, p/n 2732, flat steel, covers the Q-Jet bores, mates with the square flange carb, stops leaks. then, there are various adapters that are thicker, do the same thing.
On some square flange manifolds, there might not be enough metal on the sides of the carb pad to properly support the carb to manifold gasket, allowing it to 'droop', and cause a series of small air leaks, that become one large one. Same fix shaould work 2732 will seal the plate to the manifold, and carb to the plate.
There are options, but, first, find the leak, if you have it, sue the propane, it works well.