So I recently rebuilt a 22r for my pickup. I installed the motor and everything was working really great with the one exception that if I spray carb cleaner around the areas where the intake manifold joins to the head I got a fairly substantial increase in engine RPM. Coolant also travels through the intake manifold and into the head of course but the coolant is perfectly sealed. The truck really drove quite well but because of this apparent leak I took the intake manifold back off. This time I bought a Felpro intake gasket (one of the ones with the red sealing strips around the ports). Really looked like a top notch intake gasket and much better than the previous gasket I used. I also took a dead flat aluminum bar and level sanded the intake manifold joining surface. I cleaned everything up and reinstalled with the new gasket and made sure to torque everything to spec. Aaaaand it's still increasing pretty substantial in engine RPM when I spray carb cleaner around the base. What would you do?

 

Sounds to me like you may have a vacuum leak in the area but not necessarily from the manifold gasket. Either a missed vacuum hose or possibly a crack in the manifold. I've never had issues with new manifold gaskets leaking provided the surface was clean. By the sounds of it, you took care to make sure it seals and I suspect it did seal.

 

That's a good thought. However I have every single element of emissions control removed and absolutely no vacuum lines other than two lines for the vacuum advance. I'll have to get back out there and continue spraying carb cleaner around and see what may come to mind...

 

I just sprayed carb cleaner all around and it seems that it really mostly happens once the engine gets hot. Upon first startup when it's cold it doesn't do it. As the motor gets hot the idle goes up really quite a bit. Really seems like it's coming from the intake to head connection. It's possible that it's the base of the carb too though...