I have a frustrating vacuum leak between my carb and intake. I tried 3 different gaskets, the last being a thick insulator gasket from Edelbrock.

It is a Demon 650 vac sec / Edelbrock Performer RPM combo on a 350.

any suggestions? I'm thinking something is a little warped.

Warpage could be your issue. is the carb or intake used/old? Ive had stupid vacuum leaks from forgetting about vacuum lines or caps, you could check that. Does the throttle shaft have any play in it?

Also check for cracks in the carb base plate. I've also seen a Holley main body that was not milled level and pulled the base plate out of level when screwed on.

I will probably have to take a magnifying glass to the carb base area to see if there any cracks. The carb/intake are only a year old, so I would hope there is no warpage.

Is that a manifold for a squarebore (Holley) carb? If not, you need to use a metal plate to adapt from squarebore to spreadbore with gaskets on both sides. Massive vacuum leaks will be the result if you don't.

Have you tried locating the vacuum leak by squirting little shots of carb cleaner around it?

The manifold is for a squarebore carb.

Seems the leak is coming from the front of the carb base/manifold location via the carb spray method

nt meaning to hi-jack your thread but im having the same problems with my proform/edelbrock perfomer combo. i have to use the adapter plate and was wondering if i need to install a gasket on each side of the plate?

yes a gasket is needed on both sides of adapter plate..

1 gasket to seal plate to intake, second gasket to seal carb to plate

Couple of suggestions:

The easiest suggestion and the one I'd try first, use gasket shellac on both sides of your gaskets and then reassemble. Dont overtighten the carb bolts (single biggest source of warpage) and do tighten them done together. (Meaning: Dont crank one bolt down all the way and then move to the adjacent bolt. Use a criss-cross pattern and gradually snug all four bolts down together.) I dont know what the foot-pounds of torque is, but a C-hair past snug should be fine.

Harder: Put a piece of very, very fine wet-dry grit sandpaper on a flat surface and slide the bottom of your carb across it. It will quickly reveal how flat the bottom of your carb it. You can continue to sand the bottom of your carb this way until it's perfectly flat.

Oh yeah, before you do any of this stuff, get a spray bottle of water, and with the engine running, spray around the base of the carb (and the intake in general). When you hear the engine rpm change, you've identified the source of your vacuum leak.