91 trans am tpi to carb
Thread Starter
Junior Member
Joined: Jun 2014
Posts: 11
Likes: 0
From: Hamilton ontario
Car: 1991 pontiac trans am Gta
Engine: Lb9 5.0 soon to be L98 5.7
Transmission: 700r4
Axle/Gears: 3.27
91 trans am tpi to carb
looking to swap my 91 trans am from 305 tpi to 350 vortec carb has any done this kind of swap if so what wires did u keep and what wires did u get rid of thanks.
Joined: Mar 2000
Posts: 43,187
Likes: 42
From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
From the homepage, How-to's tab, this article is listed: https://www.thirdgen.org/carbswap/
The entire EFI harness can be removed without cutting anything. Follow it from the passenger side fenderwell, disconnect everything it connects to (including going down to the transmission). Then go under the passenger side dash, remove the upper panel and kick panel. Disconnect that harness bundle form the ECM, unclip the bulkhead connector that passes through the body panel, pull that entire bundle up and out of the engine compartment.
All the wires you need for the carb is still in the car.
The article doesn't mention it, but you'll need a Vortec-specific intake manifold. You'll also need an older carb-type thermostat housing (angled, not straight).
Since you have an automatic transmission, you'll need two things not mentioned in the article: A TV cable geometry corrector bracket for the carb you use, and a means to lock up the torque converter clutch.
I would also recommend getting a carb 3rd gen accelerator cable and TV cable. The TBI parts will also work. Much easier than trying to route the excess length of the TPI pieces.
I would recommend the return-type fuel pressure regulator. Mechanical pumps aren't that great.
On another note, any reason you aren't just getting a Vortec TPI base (or full Vortec TPI intake manifold like the Stealth Ram) and keeping TPI? Frankly, that's what I would do. Much less work. Better driveability. Better longevity.
The entire EFI harness can be removed without cutting anything. Follow it from the passenger side fenderwell, disconnect everything it connects to (including going down to the transmission). Then go under the passenger side dash, remove the upper panel and kick panel. Disconnect that harness bundle form the ECM, unclip the bulkhead connector that passes through the body panel, pull that entire bundle up and out of the engine compartment.
All the wires you need for the carb is still in the car.
The article doesn't mention it, but you'll need a Vortec-specific intake manifold. You'll also need an older carb-type thermostat housing (angled, not straight).
Since you have an automatic transmission, you'll need two things not mentioned in the article: A TV cable geometry corrector bracket for the carb you use, and a means to lock up the torque converter clutch.
I would also recommend getting a carb 3rd gen accelerator cable and TV cable. The TBI parts will also work. Much easier than trying to route the excess length of the TPI pieces.
I would recommend the return-type fuel pressure regulator. Mechanical pumps aren't that great.
On another note, any reason you aren't just getting a Vortec TPI base (or full Vortec TPI intake manifold like the Stealth Ram) and keeping TPI? Frankly, that's what I would do. Much less work. Better driveability. Better longevity.