TBI vacuum leak at manifold

**Kitch** · 03-14-2019

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** · 03-14-2019

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

**Daveo91** · 03-14-2019

Originally Posted by CDeeZ

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** · 03-14-2019

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.

**Daveo91** · 03-14-2019

Originally Posted by 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.

Cool, thanks. Yeah, I'd probably go that way too. Looks like you're using the GMPP TBI-specific intake for Vortec? Happy with it? I wish I would have gone that way even though they seem to be a lot more expensive. I wouldn't be having the vacuum leak problems I'm having now.

**Kitch** · 03-14-2019

The manifold seems okay, I'd have liked something a little more high rise but the GMPP manifold is the only one I know of with the factory style water passage that links the front of the heads to the back of the heads. It was expensive and then I had to get it bored out for a 46mm TBI unit and block off the EGR ports.
I also decided to block the EGR ports in the bottom of the runners because I thought fuel might pool in there.

**Daveo91** · 03-16-2019

Originally Posted by Kitch

The manifold seems okay, I'd have liked something a little more high rise but the GMPP manifold is the only one I know of with the factory style water passage that links the front of the heads to the back of the heads. It was expensive and then I had to get it bored out for a 46mm TBI unit and block off the EGR ports.
I also decided to block the EGR ports in the bottom of the runners because I thought fuel might pool in there.

Yeah, the q-jet manifold for Vortec is easier to find used. I've bought two now, both only slightly used for about $150 each. Mine has EGR provisions as well, and I'm not using it. I've got a block off plate where the valve goes, but I didn't do anything with the ports in the runners. You've got me a little nervous now - when I had everything off tonight I could see a small amount of fuel down those holes. What did you use to block them?

**Fast355** · 03-17-2019

Originally Posted by 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.

Not to get too off topic, but I went a little different way with mine back in the day. Running a mass air flow sensor on the TBI and used a Caddy intake bonnet that had a built in power bowl.