I recently acquired an 86 Iroc minus the engine. I have an 350 out of an 87 chevy P/U. My question is the original engine was a 305 tpi, and what I'm going to is a 350 tbi. What kind of complications am I going to have with the computer? Where can I find a wiring adapter? And thirdly will this even work? I know there have been answers to this question before, but every one I find states remove certain things of the original engine. Which I don't have.

 

Welcome to thirdgen.org.

Is there anything of the TPI left in the '86, such as the harness that come into the engine compartment from the driver's side fender?

Well, I guess it doesn't make much difference, since none of that will work for TBI. You need a TBI computer and harness (some have used the truck stuff, I don't know further details). Hopefully the harness that comes from the driver's side of the firewall is all still there.

This is more of a TBI question than engine swap, so I'll move this over there.

 

I have the computer out of the truck, but I would still need the original computer for the transmission and things like that wouldn't I?

 

I just completed a 305 TBI to a 350 TBI swap and as long as you have the TBI harness and 350 TBI ECM then your golden. I used my 305's wiring harness and it hooked up great. and the tranny wiring is in the wiring harness.Its only a 4 connection clip-on connector.(700r4 anyways)

 

Wow thanks, I appreciate it. There is one thing I need clarification on though. You said as long as I had the tbi harness and ecm, which is the chip in the computer right? then I am golden, then you said you used the 305's wiring harness. which one do I use?

 

The 350 and 305 TBI harnesses are the same, and the ECM is the whole module(the silver box with 2 connectors on the bottom) The entire computer... thats all you need. As long as everything is hooked up it will run. Good luck

 

Hey Man Thanks SO Much, I Really Appreciate It!!!!!!

 

remember yours is a **TPI*** not TBI so go to the junk yard and get the wiring harnes for a car like yours FOR TBI and then install you engine and wires. befor starting it make sure all the sire are correct.

 

I also have a problem im changing out my 305 for a 350 also, however the 350 does not come with the computer or wiring harness... will i be able to use the computer and wiring harness from my 305?

 

how about a hsr or getting a carb intake with direct port injection, i think the speedos are differant in the tpi vs. tbi

 

Not if its TPI, TPI harness will not work with TBI.

 

Sorry to hijack the thread, but are there major differences between TPI / TBI harnesses at the firewall junction?

Lets say I have a 1985 TA that originally had TPI, can I purchase a 1988 TBI harness and it will plug into the firewall with no mods? Are there any differences in the connectors between years?

I am picking up a 1985 TA sometime this week from my brother that has had the TPI removed and the harness cut. Since I don't want to pour a lot of money in it and want to make a dependable decent driver......I thought about doing a TBI retrofit along with a good used 1988-1992 TBI engine, harness and computer since they aren't as expensive as TPI.

I've got TPI on my 82 Corvette and that about broke me

 

There was a cool site I saw from a link here once that sold all kind of different wiring harness and connectors. All new stuff, that they cut / soldered / put all the right connectors on. I think it was more of a TPI store, but they might be able to help you out with a TBI harness. I forget the website, but somebody might have it.

As for the ECM, you might want to consider looking into the EBL flash. It is the best way to custom tune your TBI car. Basically, you can buy an ECM from them, for your application, and it will already have the EBL chip and wires soldered into it. It basically replaces a stock ECM, and allows you to live Datalog, and flash new .bin to your ECM. And other cool stuff.

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The other option that might be worth considering, is you could pick up a used TPI intake setup, and swap that on top of the LO5. If your TPI car was the MAF type, you could even get away with a mild cam swap and nice exhaust on a stock tune probably.

I dont know how much the TPI would cost, but you could compare that to the cost of a wiring harness, ECM, and all the other TBI sensors and accys. Hehe I imagine a flat-tappet 350 TPI would sound really mean and pissed off!