TBI vacuum leak at manifold

[S.O.B.B.]

If u put grease like bearing lube etc on the gasket surfaces both sides it makes seeing the leak easy if it won't seal.it sometimes leaves the gasket in non reusable state if paper surfaces peel.but still makes where the leak is easier to see when the TB and adapter are lifted off.I'm using self made adapter because I'm using a dodge TB where the gm one was but I'm using the thin style gaskets with out issue.the grease trick I learned years ago from an older mechanic and I've used it ever since with out any issue.hth

[Daveo91]

If u put grease like bearing lube etc on the gasket surfaces both sides it makes seeing the leak easy if it won't seal.it sometimes leaves the gasket in non reusable state if paper surfaces peel.but still makes where the leak is easier to see when the TB and adapter are lifted off.I'm using self made adapter because I'm using a dodge TB where the gm one was but I'm using the thin style gaskets with out issue.the grease trick I learned years ago from an older mechanic and I've used it ever since with out any issue.hth

Thanks, I may try that. I took the adapter out tonight and it's not obvious where/why it's leaking.

[CDeeZ]

Ditch that spacer ring that raises the aircleaner housing up. GM used a drop base aircleaner, but it hit the coil or anything else so they then threw that little spacer choke ring on there. TBI breathes from the side since the injectors and pod hang over the throttle bores. But that spacer chokes off the air from the side. Hypertech sells something called a "powercharger". You can make the same thing out of a salad bowl, that's what I did.

[Kitch]

As CDeez mentioned, I just went out and bought a salad bowl roughly the size I wanted and trimmed the base out of it and added a rubber strip top and bottom.
I'd have maybe bought a powercharger but the freight cost to NZ meant making my own was way cheaper.

[CDeeZ]

Looks as good as the powercharger. But you made it so it's better!

[Daveo91]

Looks as good as the powercharger. But you made it so it's better!

Agreed, that's pretty cool. Do you have an outlet for the PCV system, or do you just use a breather mounted on the valve cover?

So I'll definitely consider that mod, but I first need to figure out this sucking air problem. I've had the adapter out four times now with different gaskets and/or light coating of grease, but nothing helps. I can actually hear the leak now and can change the sound of it by touching the part of the gasket that overhangs in front. I've come to the conclusion that the 454 adapter I'm trying to use does not bear correctly on the GMPP intake. I don't really see why, but I have no other explanation, the adapter is not warped or gouged. Fortunately I have another option. I also have this aftermarket adapter and I'm going to switch to it. I didn't use it originally because the OEM one has a vacuum port that I was using for my brake booster and there's also a coolant passage to aid in cold weather operation. But it's running fine in cold weather without heat and I'll use the port on the manifold for brakes.

[Kitch]

I looked at trying to add a hose from the salad bowl to the rocker cover but in the end I just fitted a breather into the rocker cover.