Throttle body injection question

[DaveB]

I have a couple of GM engines that I would like to convert over to TBI from carburetors. I have seen listings for kits that let you do it but they are a bit pricey. The engines that I have are a couple of GM crate motors one is a 350 from my brother's Blazer thats going into a family jeep project and the other engine is a 502 in my one ton trailer puller. If I found the TBI units, sensors, and wiring from a wrecked truck shouldn't I be able to make my own TBI swap ? I know I would need a manifold adapter or a new manifold.
Would a TBI from a 454 work for the 502 ? would it give it enough fuel ? Any one done this swap who can enlighten me?

 

[ALF]

Not sure on a 454-502 tbI but a 350-350 tbi should be a straight over swap even the stock intake off the tbi will work with a little modification, there are tons of step by step write ups on the net.

 

[4554x4]

Tbi

Check out TBICHIPS.COM Brian has a write up on the SS454 pickup modifications. I am doing a simular swap on my truck that I pull my trail rig with. I think I will be pushing the flow limits with my engine at 468 c.i.d. Jim at Jims performance might be helpfull also.

 

[Caleb]

I'm far from an expert but I could have sworn the TBI units from 350 up to 502 were pretty much the same just with different injectors??? It's very much possible to do what you are looking to do, you just need to make sure you get everything.

 

[DaveB]

Thanks for the info, I'll have to do some more web research. I did score some of the parts I'll need for the 350. I picked up a TBI 350 that a guy was selling from a 90 suburban. I ended up with the intake manifold, throttle body, and several of the sensors. I just need to find the rest of the sensors, the controller, and wiring.

 

[brokejeep]

I just put a 350 tbi on my amc 360 and with the help of "russelle" who burned me a new chip it runs great. I found a aftermarket tbi harness on ebay for $150 that is new and comes labeled. I converted the amc distributor to work. I have an extra 350 throttle body that needs new gaskets if you interested. Moates.net has alot of products to make the computer programable so you can adapt it to your needs.

 

[brokejeep]

I forgot.... binderplanet.com and other international sites have the most information on the swaps. Did you find the grill you needed?? I have one if you still need it.

 

[DaveB]

I just put a 350 tbi on my amc 360 and with the help of "russelle" who burned me a new chip it runs great. I found a aftermarket tbi harness on ebay for $150 that is new and comes labeled. I converted the amc distributor to work. I have an extra 350 throttle body that needs new gaskets if you interested. Moates.net has alot of products to make the computer programable so you can adapt it to your needs.

Thanks, I'll check out those sites. What did you do to the AMC distributor to make it work ? How much would you need for the TBI ? I still need to find out if the 502 could use the same TBI body with different injectors or if it needs a bigger bore size.

 

[DaveB]

I forgot.... binderplanet.com and other international sites have the most information on the swaps. Did you find the grill you needed?? I have one if you still need it.

I did pick up a grille but it needs some cracks fixed. What is the grille that you have like ? and how much would you want for it ?

 

[Tacoma]

454 TBI has a bigger bore size on the actual throttle body too, if I'm remembering right. I have a spare 454 throttle body, but I'm 3mos away from you.
The injectors flow more fuel too, and I am pretty sure you can upgrade those as well, depending on your 502's specs. I had plenty of power in the work truck, and I don't think I ever got past about 3/4 throttle, ever.

also: you can use a stock 454 q-jet manifold, as stock big block TBI uses an adapter plate... or you can spend a lot of money on the Edelbrock TBI intake.

 

[DaveB]

454 TBI has a bigger bore size on the actual throttle body too, if I'm remembering right. I have a spare 454 throttle body, but I'm 3mos away from you.
The injectors flow more fuel too, and I am pretty sure you can upgrade those as well, depending on your 502's specs. I had plenty of power in the work truck, and I don't think I ever got past about 3/4 throttle, ever.

also: you can use a stock 454 q-jet manifold, as stock big block TBI uses an adapter plate... or you can spend a lot of money on the Edelbrock TBI intake.

I can wait 3 months, I have so many projects now that I won't have time for the 502 for a while.

 

[jsudar]

The 454s have much bigger injectors and the throttle body is different (larger.) I know there is a pretty wide range of different sized injectors available for the TBI setups. You should be able to find an injector with the right PPH. Another option is dual throttle bodys. Turbo City used to have a kit that allowed you to run two TBI 350 throttle bodies. It was kind of like the old Crossfire injection, but it didn't suck.

You can do a lot just by bumping up the fuel pressure. FWIW Kurt's auto wrecking in Orem has a 454 TBI. The TB was already gone, but most of the other stuff was still there.

 

[neagtea]

502
Use the big block throttle body and bump the pressure. That is the cheapest way to go. If it is not perfect open up the wallet as the skys the limit to get it perfect.

 

[tv_larsen]

Have considered a Mega-Squirt system?

http://www.diyautotune.com/tech_articles/megasquirt-carb-to-efi-part1-nova.htm

For the 502 you may want to consider the 4bbl Holley TBI throttle body instead of the stock 2bbl 454 unit.

 

[brokejeep]

The nice thing about moding your computer with the moates set up is you can adjust the amount of fuel the injectors push. For my 360 the stock chevy was way to much fuel and this was off a 350. You can adjust the timing and everything and the set up you can have real time numbers with the lap top hooked up. The grill I have is clean, I would like to get $50 for it. I also have a chrome grill cover that is also for sale the 350 TBI I would let go for $40 with a harness but I have not looked at the harness. Really Russelle on this forum is the man to talk to. As far ans my distributor went I followed the build on bustedjee.com get everything working that is a very good right up. The instruction are the same for the straight six or v8.

 

[DaveB]

Thanks for all the info, I'll have to do a bunch more research when I get a chance.