TBI replacing carb
 

Has anyone fitted throttle body fuel injection on an 70s chevy V8? My truck guzzles fuel and I'dd like to ditch the carburator. It's not funny, maybe 8 mpg:(

first of all, I know it isn't a V8 but my buddy is fuel injecting his chevette with a system called mega squirt. it is a very indepth system that you build yourself. he just got the kit and says it will take him about a month to put on because he needs to find other random bits to use like the throttle body, sensors, high pressure fuel pump. he already has another gas tank.

he is trying to make it to where there is not downtime with the car when he does the change over. he his hoping for more power and better FE.

I'll talk to him about the system and ask him what is different if it is done on a V8 vs his 4.

What type of 70's V8 Chevy truck are you talking about? With some relatively minor mods I was able to get my old 1974 Chevy C-10 pickup with a 350 V-8, Turbo 350 automatic tranny, and a Rochester Quadrajet carb turning almost 30 on the highway (with the a/c on!!!). They were great because they didn't have all the emissions crap on the engines to reduce mileage.

Here's the mods I made on my old truck:

Added cruise control

I flipped the bonnet on the air cleaner upside down so the engine can breathe easier.

I replaced the points type distributor with an electronic one from a 1980 Chevy truck with a 350 V-8 (from junkyard)

Switched to Platinum spark plugs, and increased spark plug gap when I switched to electronic distributor.

Even with over 300,000 miles on it that truck ran great, got great mileage when I was kind to the accelerator, but when you wanted to move in a hurry that thing would nail you in the back of your seat.

-Jay

I put a Holley Projection on my Buick 455 back in 1992. The worst part was the extra fuel lines- my original car didn't have a return line, and the supply line was too small. So I put in a new 3/8" supply line and 5/16" return line.

For me, the wiring part wasn't too bad, but I'm better at wiring than at plumbing.

-Bob C.

With mileage that bad, I'd look for something obvious, like a stuck choke. A stuck choke will make a truck gulp fuel like crazy.

You didn't say how big the engine is, or what the axle ratio is. A complete motor or axle swap might be easier than trying to modify an engine.

No kidding, I had a 1.3L car with an auto choke that screwed up, it got 25mpg, then I ripped the auto out and put a manual kit on it and got 35mpg.... then I later has some other issues with that carb and replaced it with a very low miles original carb, with the auto choke intact, and that got me 40mpg.

The auto choke on my 74 chevy was real simple. It was a flat, coiled spring bolted to the intake manifold. The spring would expand and contract with the temperature of the manifold, shutting off the choke when the engine warmed up. Adjustments were easy, I just bent the pushrod connecting the choke to the spring. Check your spring and see if it isn't broken from age... Should be a cheap, easy repair if its broken.

-Jay

I would love to convert my 1980 Buick to TBI, but the more I learn, the more I think the project is beyond my ability and budget. Apparently it can be done pretty reasonably with junkyard TBI parts from a Chevy Astro. However, I think it requires a pressurized fuel system, return lines, etc...

I would like to do it to my 81 Regal as well, but to do it right I think I would have to start with a decent parts car.

-Jay

Take the TBI stuff off of an 88-93 Chevy or GMC truck. My 89 Chevy was TBI. I believe they ran it until 93, give or take a year. Pretty basic, and fuel pressure is not very much, like 15 tops I think. Taking everything you need off of one of those trucks from the intake manifold up. Take the wiring harness and computer also.