TBI 87 350 to 454

[GmtGmt]

Im going to build a 454 with tbi for my heavy hauler project. but can i take a throttle body, wiring harness and ECM from a 350 truck?

Thanks Thomas

[BigBlocksRule]

Harness is fine, ECM will need a reflash.
The throttle body will be too restrictive, your 454 will be breathing through a straw. Find a good rebuildable 454 throttle body and go from there.

[STOCKISH]

I agree. The 5.7 TBI will kill that 7.4

[gchemist]

Call this company to upgrade your TBI.
http://cfm-tech.com/GM_tbi_tuning_tips.htm

[rfmaster]

Originally Posted by BigBlocksRule

Harness is fine, ECM will need a reflash.
The throttle body will be too restrictive, your 454 will be breathing through a straw. Find a good rebuildable 454 throttle body and go from there.

BBC TBI uses a different style IAC which will require a connector swap. The easiest thing to do is to get BBC from JY with mating connectors attached (in pig tail form)



Alternately BBC IAC uses GM#12126487; AC-Delco #PT757 or Pico-5602 pigtail.

The 1227747 ECM uses 2732A UV PROM chip (which is not the same as FLASH) - which is notoriously prone to failure! The easiest way to get around this 25+ year old chip is to install modern Flash chip AT29C256 or 27SF512 in G2 adapter. For detailed information see http://www.moates.net

//RF

[BigBlocksRule]

^ forgot about the IAC connector when we used a 454 TBI on my son's 383 vortec stroker conversion. Seems like there was one more wire that was different but I can't remember what it was...

[rfmaster]

Originally Posted by BigBlocksRule

^ forgot about the IAC connector when we used a 454 TBI on my son's 383 vortec stroker conversion. Seems like there was one more wire that was different but I can't remember what it was...

Yep memory goes, but with the help of notes:

The correct wiring for the 7.4 IAC valve is as follows :
ECM Con Color
C3 Pin A Lt blu/blk - Coil A Low
C4 Pin B Lt blu/wht - Coil A High
C5 Pin C - Lt grn/wht - Coil B High
C6 Pin D - Lt grn/blk - Coil B Low