I have an 87 Camaro with a 305 and a bad carb. It came stock with a TBI though so all the hookups are there. I would rather move it back to TBI since I'm gonna have to replace this thing anyways. Where can I get just an average TBI off of some old car? What would work and what wouldnt? Does the computer automatically adjust the flow from a 4.3 TBI to the Camaro's 5L? I just need something cheap to get it to run correctly and drive down the road and I have lots of cars to pull stuff from so let me know!!

 

You'll need the computer from a 5.0 liter for sure. The throttle body aint a big deal, I'm not sure if they had different injectors on the 5.7 or 5.0, but try to find a computer from a 305 Camaro as well as the throttle body. BUT, the throttle body from a 5.0 truck should work as well...

 

Ok well it has a computer and everything like i said it was originally a TBI motor but the last motor threw a rod so me and my dad put a new one in it and he just threw a carb on it. So basically I just need to find a truck or old van with a throttle body I can yank off of it..I cant wait to get it running again! Anymore info anybody??

 

Injector sizes are different between the engine applications, so you'll want to find one from a 305. It shouldn't be very hard to find one though, have you looked on flebay or Craigslist yet?
And you'll need to reverse whatever was changed on your fuel supply system. TBI, as well as other FI setups use a fuel pump in the tank. Fuel pressure would be too high for a carb to handle, so whoever converted it to carb would have needed to either remove the fuel pump from the tank (you hope not), or would have installed an inline fuel pressure regulator. How was the fuel pumped the way it is now?

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Oh, really? Hmm. Well the car has never been right. When I start it it runs real bad and waaay too rich, and backfires some. I dunno why but its too nice not to drive..I know the fuel pump is in the tank and I've never really looked at it. I'm trying to get it out of the yard and into the garage but when I put it in drive it dies..

 

Another hmmm....If the person who did the carb swap didn't know what they were doing, and just slapped on the carb without changing anything else in the fuel supply, then that could be your problem right there.
The pump in the tank puts out too high a pressure for the needle & seat in the carb to hold back. An overflowing carb and rich output would be the result. If the stock in-tank pump is still being used, there should have been a fuel pressure regulator installed somewhere between the tank and carb to step it down. If there isn't one, the fuel pressure is too high for the carb.

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I see. Well in that case I'll go grab one out of the junkyard tomorrow and slap it on there and see what happens. If it doesn't start I'll know theres a regulator on there somewhere and I'll just get the carb rebuilt I guess..

 

hey, how hard is it to go swap in a carb if it was originally a tbi?

 

Intrepid, it may not be quite that easy. Was the intake manifold changed, or did they use some sort of "adapter" to put the carb on? A changeover isn't a simple matter of removing the TBI and bolting on a carb.
Gordon, is there a good reason why you want to switch to a carb? A good working TBI works quite well, and I don't think there's going to be a large benefit (if any) in swapping to a carb. to make it worth the time and expense involved. But if you're building up a race engine, and avoiding computer tunability issues are the reason, then that's a differerent story.
Both you guys should read this tech article on swapping from TBI to carb: TBI to Carb Swap
Gordon can use it as a how to guide, and Intrepid can use the info to "reverse engineer" what he has now.
One of the things in the article that I don't quite agree on is where he mentions the stock fuel pump not being sufficient with a bigger motor. Don't let that part scare you. If you've ever changed the in-tank pump, you'll know that going the pressure regulator route is going to be waaaaay easier to do.

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Honestly you're probably right. The motor thats in it now is a 305 from a blazer so the intake is probably for a carb. Could the accelerator pump be the cause of my problem? I was told thats what it is but I'm not exactly a regular mechanic and I'm more used to working on FI than I am with carbs.