87 454tbi to 92 350 tbi swap question

[woodie87]

Hey guys if this is covered I apologize I couldn't find it..
Is the harness diff between my 87 454 and my 92 350?
Both tbi. I realize the ecm would need to be changed, but does the entire harness need to be swapped if I decide to do this. It would be temporary untill I can afford to rebuild my 454.
If I would need to change harness and all I will simply let my 87 sit untill I can afford to rebuild it. Thanks

 

[Jims86]

Hey guys if this is covered I apologize I couldn't find it..
Is the harness diff between my 87 454 and my 92 350?
Both tbi. I realize the ecm would need to be changed, but does the entire harness need to be swapped if I decide to do this. It would be temporary untill I can afford to rebuild my 454.
If I would need to change harness and all I will simply let my 87 sit untill I can afford to rebuild it. Thanks

All you need is the proper chip for a 350(I assume the 87 has a turbo 400 trans) which we can figure out, and swap the light blue and green wires on the IAC plug. Same ECM, unless the 92 has an Electronic transmission. Make sure you use the 350 throttle body.

 

[X-cabsquarebody]

Hey Jim, isn't the plug on the TPS and EGR solenoid different?

 

[Jims86]

Hey Jim, isn't the plug on the TPS and EGR solenoid different?

Ahh yes, the TPS uses the round plug. No problem to splice them over for the time being Good catch X!

 

[bucket]

Without digging through my parts and harnesses, I thought the IAC plug is different too. The 350 uses the big square connector while the 454 uses the flat connector.

 

[bucket]

You could also run the 454 TB on the 350 to keep things simple. Just use the 350 injectors.

 

[Jims86]

Without digging through my parts and harnesses, I thought the IAC plug is different too. The 350 uses the big square connector while the 454 uses the flat connector.

Ummm....I think the only flat one was used on a 350 in the 96 1 ton G van, and the export tahoe...both were the obd1 TBI topping an L31 Vortec. It really depends on which throttle body they used on his 87....Both styles of IAC are listed for the 454 from 87 up. He needs to confirm that he can achieve wide open throttle on the 350 manifold with the BB Tbody without binding, but yes, he could swap the injector pod from the SB to the BB T body, and should work just fine.

 

[bucket]

Ummm....I think the only flat one was used on a 350 in the 96 1 ton G van, and the export tahoe...both were the obd1 TBI topping an L31 Vortec. It really depends on which throttle body they used on his 87....Both styles of IAC are listed for the 454 from 87 up. He needs to confirm that he can achieve wide open throttle on the 350 manifold with the BB Tbody without binding, but yes, he could swap the injector pod from the SB to the BB T body, and should work just fine.

The style with the two little mounting screws has the flat plug. I've got a setup from an '87 and a '91, curiosity makes me want to take a look.

As for the openings in the 350 manifold, I'd just violate it with a die grinder or a flap wheel.

 

[Jims86]

The style with the two little mounting screws has the flat plug. I've got a setup from an '87 and a '91, curiosity makes me want to take a look.

As for the openings in the 350 manifold, I'd just violate it with a die grinder or a flap wheel.

Or just take the manifold to a machine shop, that way, he can take full advantage of the 2" barrels!