4.3 to 5.7 conversion question?

[yoda1888]

I have a chevy truck wit a 4.3 an 4l60e. Im putting a 5.7 in it an want to stay wit the tbi set up. Anybody know what all i wil have to change as far as wiring or computer? Help needed! ..
Thanks.

 

[Bronco Buster]

From what I have been told about doing the same swap in my S-10. It is all plug and play just change motor mounts and go. A 4.3 TBI will work on a 5.7 but the 5.7 TBI does have bigger injectors. The fuel pump and/or ECM do not know the difference in TBI's.
This is all hear say from me asking around about the same swap I have not tried it yet. Let me know what you come up with and if it works.

 

[doctordick]

Not a Vortec, right?

Been there, done this. Change the injectors (throttle body is the same) to 5.7 and the chip or ECM . Good to go.

 

[yoda1888]

Thanks for the info guys. I'm going to be finishing it up tmw so bronco b. I,ll let you know how it turns out.

 

[Bronco Buster]

How did the swap go?

 

[yoda1888]

Went good only problem I'm having is a rough idle. I swaped the injectors an it will run the same with either computer. I cant tell the difference between the 4.3 an 5.7 computer

 

[garlandg]

check your timeing computer may be maxing your advance out just to keep it running

 

[yoda1888]

I have it in time. Thinkin it might be a bad egr.