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Discussion Starter · #1 ·
I have a 89 GMC pickup and was looking to re-power it. I decided on a ready to run v-8 350 with a 650 cfm edlebrock carb. THe problem is that the existing engine is a 4.3 liter v-6 with the tbi system. My question is how to i now avoid my ecm when installing the new engine. When reading through the manual on the v-6 i noticed all the relays an such that are sent to the ecm which allow it to run. i don't want to get stuck with a brand new 350 that doesn't run because of the previous computer. the catch is i would like to avoid re-wiring the whole system if at all possible. any help on the subject would be greatly appreciated.
 

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It will be easier to rewire your new setup than try and fit the old wiring to it. You really wont have that many new wires to run.

You'll also have to change to a lower pressure fuel pump.

Do a search of this forum. It has been discussed many times.
 

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I don't want to be negative but.....
Maybe it would be best to sell your truck and buy one with a 350 already installed by the factory.

Or, have you considered a turbo charger and a boost sensitive fuel pressure regulator for your 4.3. Seven psi of boost is 50% more hp and torque!
 

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You can retain the TBI with the 350 engine as long as you use the V8 distributor`s components. As long as the engine is stock, it`s a slam dunk. We`ve recently did this twice, used the throttle body from the 4.3 on the 350. This would be your easiest and cheapest way out. TBI is far better than any carb dreamed of being, If I already had a TBI I would stay with it. I don`t know what book you`ve read, but I know this can be done, we`ve already did it and it was easy. I`m sure the mounting locations are already there on the frame of your pickup. You should be able to reuse the knock sensor from the 4.3 being that the bore and stroke of the 4.3 is the same as a 350, the 4.3 just say 2 less cylinders. We took a 73 350 and installed it in a 1992 chevy truck that had a wasted 4.3, we got the intake off a TBI 350 out of the junkyard, and used the other V8 components, we didn`t even swap the computer.
 

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Discussion Starter · #5 ·
As for using the trucks previous tbi, coming from a 4.3 would i be able to use this injection system and get the same kind of horsepower it would get if i were to use a 650 cfm carb. it just seems to me that the throttle body that came on the 4.3 would not give proper air flow to the larger v-8. just courios, what year was the tbi unit you used?
 
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