Thread: 89 Chevy TBI to Carb

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I've been looking forward to taking the truck and building a 400 horse engine for it, but everyone says the most I will be able to get with the TBI on top will be around 340 or less, and I would rather get rid of all the electrical stuff.

Originally Posted by dcurtis

I've been looking forward to taking the truck and building a 400 horse engine for it, but everyone says the most I will be able to get with the TBI on top will be around 340 or less, and I would rather get rid of all the electrical stuff.

You can make about 350hp with a TBI but the tune and everything has to be right. TBI just don't support enough flow unless you went with a 454ss TB or Holley 2" bore.

To go from a TBI to Carb, you will need to put a fuel pressure regulator on it so that it only flows 5-7 psi instead of the 11-18 psi currently. You will need to keep the computer so that the guages work and the lockup for the tranny still works. Any other questions, just ask.