Quote Originally Posted by Daveo91 View Post
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’m using stock style gaskets for the BBC application both above and below the adapter. They’re both very thin, but I’m wondering if I should be using a traditional q-jet bas gasket which is much thicker? Any other suggestions?

Here’s 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’m not using that feature.

7DC004F9-92DA-4057-AD3F-42F5C02F62ED.jpg
You say the leak is not being caused by the pipe plug but did not say how you verified that. The adapter is hollow (coolant passage) and pipe plugs are tapered. I am wondering if the plug when tighten, is distorting the adapter? If you were to remove the pipe plug, do you note any changes?