Will it work?

[Ray petru]

I have a 1989 Chevrolet dually that had a 454 going to a 5.7 from a 88 GMC taking out all the under hood wires and computer from 88 to 89 .89 has a 400 transmission where 88 had overdrive 700r will this work without any altering or will this set a engine light scince it won't have a4 prong hook up to transmission the 400 is vacuum control or is there some kind of kit to fool the 4prong wire

 

[Wes Harden]

So both are tbi truck's, the 5.7 computer won't like the th400. It will set the check eng light.
The big block computer might suit your needs better.
Most if not all the wiring should be the same for either motor.
I would install the 5.7 use as much of the original big block wiring and big block computer.
Give it a go.

Welcome to CK5

 

[HankScorpio]

The wiring for the throttle bodies use different connectors for 454 and 350. You will have to swap the connectors. A 454 throttle body has larger bore than a 350 one.

 

[Wes Harden]

You mean the injector plugs ?
Tps and lac should be the same

 

[HankScorpio]

You mean the injector plugs ?
Tps and lac should be the same

I ran into the issue swapping the other way from a 350 to a 454. It's possible it's an issue with the last few years though, I may have had some GMT400 stuff mixed in. I will take a look in the parts stash, still have all the parts as I moved on to proflo to run it in the end.

 

[Wes Harden]

It shouldn't be hard to remove the female pins from the big block connector and put the sbc connector

 

[HankScorpio]

It shouldn't be hard to remove the female pins from the big block connector and put the sbc connector

I ordered some replacement pigtails from rock auto.

 

[Ray petru]

I ordered some replacement pigtails from rock auto.

I have noticed that the 454 harness has no knock sensor no electronic spark control box this is on a1989 c3500 automatic transmission will this be a problem or should I use the 350 harness I generally don't do swaps just wondering how the timing is advancing without it and no vacuum advance.