1989 C2500 TBI to Carb Conversion

[gr00vin]

New member here ✌ I’m also pretty much completely new to the game. My fiance has gotten me into cars & trucks and now I have a 1989 Chevy C2500 that’s definitely a project. Of course I have lots of questions and some rough plans for the truck, and am hoping to get some advice and direction on here.

First step for the truck is to get it running again, it’s been sitting for a little while and the throttle body has seized. After some thought and deliberation I decided since I had to replace it anyways, I might as well go ahead with the carburetor conversion I wanted to do. I know that it can be done, but if I’m completely honest, I don’t know much else about doing the conversion itself.
Thankfully I have some knowledgeable people in my life that are willing to help and teach me, but I’d like to get a better understanding of what parts I need and how the whole process works before we start.

So if you’ve done the conversion before, I’d love to have a walkthrough of how you did it, what parts you used, etc!

 

[Sean Buick 76]

Hi, my best advice is to go to a junkyard and buy another throttle body and bolt it on. The TBI system may not be powerful however it’s reliable and easy to troubleshoot.

I like carbs, but I can’t really see any advantages to swapping to a carb on the stock engine.

 

[Erik the Awful]

+1. If you can't troubleshoot the TBI, switching to a carburetor isn't going to fix your problems.

 

[CumminsFever]

I once had an '89 k2500 that I carb swapped. However, it was an engine swap too, as the original one lost it's life to blown oil cooler lines.
I put an older engine in, so I started with the carb intake. For the tbi to carb swap, you'll need an intake that bolts to the tbi heads and has squarebore/spreadbore opening. I used an hei distributor, and a 3-port fuel pressure regulator. It was a fairly simple swap. I did have the th400 transmission, I don't recall that there was a kick down cable.
While I wouldn't really recommend the carb swap, if it's what you want, go for it! If you don't do the swap, and it's what you really want, you'll end up doing alot of cussing at the tbi system.

 

[Erik the Awful]

I did have the th400 transmission, I don't recall that there was a kick down cable.

TH400 doesn't have a kickdown cable. It has a vacuum line to the vacuum modulator and a switch on the throttle for kickdown. I run the TH400 in my Jaguar without the kickdown because the big block Cadillac would rather twist harder than rev.

 

[Sean Buick 76]

TH400 doesn't have a kickdown cable. It has a vacuum line to the vacuum modulator and a switch on the throttle for kickdown. I run the TH400 in my Jaguar without the kickdown because the big block Cadillac would rather twist harder than rev.

I had to disconnect the kickdown on my Skylark as when the boost came on in 3rd gear it would downshift and blow off the tires at speed. Now I can roll into boost at 65 mph without it gearing down and going hog wild lol.

 

[Schurkey]

Perhaps a moderator will move this thread to the LSX + Carb Swaps sub-forum.

Is Virginia an emissions-testing state?