89IROCTBI

Weird first post I guess, but after searching for quite some time on the subject I can't find an answer what GM throttle body will interchange with mine. The car in subject is an 89 Iroc TBI car. I bought the car as kind of a barn find and something built a mud nest around the air cleaner, the moisture from said nest has left large amounts of corrosion inside my throttle body. The plates are frozen shut with it. A few guys at work have found some TBs locally and I'm going to the Junkyard in STL Saturday. Just need to know what Throttle body will bolt in place.

Thanks,
BA

Edit: Have found an 87 350 TB, and a 95 4.3 TB, I have read that 87 is different is this true?

dctrumpet

iTrader: (10)

Please, PLEASE don't buy one from a junkyard, lol. If you are willing to take it to a shop and have it cleaned, etc and have them make sure there is no play in the throttle shaft then you MIGHT get lucky. the injectors will need professional cleaning as well ($30-$50 per set). Too much work to do with a junkyard TBI.

Believe me I get all of mine from junkyards. I have them cleaned and then I re-bush them as 50-75% need rebushing in the throttle shafts. I send the injectors out for cleaning and about 15-20% of them are bad and can't be fixed.

I would buy one rebuilt and buy flow-matched injectors, etc.

To answer your first question... Almost any 305/350TBI will work as long as the throttle linkage is the same as your stock one. Trucks tend to be different. If you dont plan on modifying your setup then you'll need 305 injectors (5235279) otherwise the 350 injectors (5235206) will be too much fuel at stock fuel pressure.

Let me see if I have a tbi base here with a correct shaft, etc.

You have 700r4?

dctrumpet

iTrader: (10)

I do have a bare base from a 92 firebird 305tbi. Shaft is tight and it was professionally cleaned 2 weeks ago. You will just have to grind off your throttle linkage and have it welded on this one as I took the linkage off to mount on my 454 TBI. You will need a complete gasket set, TPS and IAC as well. I do have a few new ones.

Let me know if you're interested at all. Not sure what your plans are for your project and how much you're willing to spend.

Base alone $60. Base with IAC, TPS and complete gasket set $150 (shipped). If you need an injector pod I will throw one in for $25 (cleaned and nice). These prices are a steal. Injectors cleaned and flow matched $75. These are 350 injectors.

I only have 55lb, 65lb and bigger injectors. I can get you some 40lb injectors for your 305.

dctrumpet

iTrader: (10)

i'm near Springfield, IL. You are near St. Louis, MO?

dctrumpet

iTrader: (10)

If your TBI is that corroded then your fuel pressure regulator diaphragm will need replacing and your spring is rusted too I am sure. See this ALL THE TIME.

I know, I know, more bad news, lol!!!

dctrumpet

iTrader: (10)

these are the pics.

89IROCTBI

I read one of your posts in a different thread you seem to know quite a bit on this subject. I appreciate your advice, but I only paid $250 for the car, and while I'm sure that your prices are very good, I am on a strict budget and that is about $120 more that I'm really willing to pay. I go to Riverside, and Pick N Pull off Hall Street quite often and am sure I can get a decent unit for cheap I just need to know what will work with what.

dctrumpet

iTrader: (10)

As long as it's a 305/350 you'll be fine. Don't go with the V6 TBI.

I understand the budget scenario! Good luck and let me know what you find ok?

ownor

iTrader: (5)

just for future reference, what's different comparing v6 & v8 TBs. are the v6 tbis single bore? sorry i just dont know and thought i'd ask this real quick here

dctrumpet

iTrader: (10)

Well, depending on the V6 the difference can be the size of the throttle bores. 4.3, 5.0, 5.7 should be the same @42mm. The 3.5L I think is much smaller and is a single bore. The base units for the 4.3, 5.0 and 5.7 should pretty much be the same. The difference can be in the fuel pressure regulator spring. Most of the 4.3-5.7L used the same spring, but I've noticed different springs, yielding different psi.

Throttle linkages can be different as well. Most of the 4.3-5.7 used the same TPS and IAC (a few variations here and there).

So.....

if you notice the stock regulator cover you will see the tab that sticks out the side of it. Most all the 5.0-5.7L units were set at the same height which is about the bottom 1/3 of the opening. 7.4L had the same regulator cover, but the tab was set to about 50% of the opening. This gave the 454 slightly more psi.

I have pulled apart about 45 tbi units ranging from 4.3L to 7.4L. I have found variations in springs and regulator covers. 7.4L bases are 50mm and the TPS can be different at times from the 5.0/5.7. THe IAC is definitely different from the 5.0/5.7

89IROCTBI

I ended up not going to a JY this weekend, it was too cold Saturday 37 degrees and windy. I pulled the old TB off of the car, looks like it's probably frozen in place via the shaft bushings. I pulled off the injector pod, IAC, and TPS, and am soaking it in an odd mixture of what I had laying around, BG 44k fuel system cleaner, kerosene, MOA, and a little gas. I'm gonna see if I can get another TB, but probably not from a JY at this rate.