I have a vacuum leak at the TBI adapter to intake manifold interface. Last night I replaced gasket and if anything made problem worse. I can spray carb cleaner in one specific spot at that interface and RPM dips noticeably (with IAC unplugged it will kill it).

my setup in a nutshell: 383 with vortec heads, GMPP vortec intake for q-jet spread bore, stock TBI to 4-barrel intake adapter from a 87-90 BBC TBI, 46 mm rebuilt and re-bushed TB, 454 74 lbs/hour injectors.

I知 using stock style gaskets for the BBC application both above and below the adapter. They池e both very thin, but I知 wondering if I should be using a traditional q-jet bas gasket which is much thicker? Any other suggestions?

Here痴 a pic. The leak is right below the pipe plug, center front. Leak is not being caused by the plug - the adapter has coolant passages to improve cold weather operation; I知 not using that feature.