TBI EFI on a dual plane manifold?

[Carnut1]

C3bx

[Carnut1]

1125171039.jpg

Modified GM TBI manifold plenum. The stock plenum sharing window shown.

[hq308]

I have a FiTech TBI on a Performer RPM air gap (308 Holden V8) with the full divider and it works fine but the fitech has channels in the baseplate so it reads MAP off both sides at the same time. Does the Fast one only read from one side?

[R.Olds]

So I talked with one of the tech guys from FAST, he said a dual plane manifold will work with a spacer (he suggested a 2" spacer) but said a single plane will always be better.
I will just sell this Performer RPM and install a Vic Jr. which I was originally planning on using until I found this Performer on my shelf....LOL

[Schurkey]

The original 1988 two-barrel GM TBI had a small open passage between the planes on my K1500. Used an "open" gasket as well.



Fighting a "lean" code at highway speed, I swapped a Treasure-Yard TBI from a newer vehicle. 1992, I think. GM changed the casting and gasket to restrict (but not eliminate) the communication between the planes. I don't know what they were trying to accomplish, and I don't know if it was successful. I discovered later that the problem with my truck was not in the fuel system, it was a faulty O2 sensor. I never bothered to change back to the "correct" TBI because I couldn't tell any difference in the way the truck ran with the newer-style TBI.