a backwards swap - Third Generation F-Body Message Boards

mikey88firebird · 10-13-2009, 11:23 PM

I have a 91 s10 2.5 iron duke and I would like to put it into my 87 firebird that has a very tired 2.8 and the way it "knocks" to say hello in the morning tells me its time is up! now the other problem i have is that the previous owner set the car up for a carb and seeing as the 2.5 is tbi, how do I make this run, is there a way i can put a carb on it? if so how?
now before everybody says "oh put a 350 in it" let me explain I dont have the money for a v8 swap and the 2.5 will bolt to my trans. And the 2.5 has less than 6500 miles on a good rebuild, its my Dads engine and the truck is now wrecked sorry so long

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Atilla the Fun · 10-14-2009, 08:23 AM

From '82-'85, GM offered the 2.5 in these cars, so what you need does exist. From mounts to exhaust, it can be found in some salvage yards from time to time. I've seen them myself, waiting to be crushed. While you're swapping the engine, and the electronics, also swap the fuel pump, pump relay, et cetera. Then you can keep the TBI.

mikey88firebird · 10-14-2009, 12:47 PM

would the wiring harness from the s10 be helpfull ? and if so how?

five7kid · 10-14-2009, 01:52 PM

I wouldn't call the S10 harness "helpful", I'd call it "necessary".

Have you considered selling the 2.5 and buying a used 3.1? You might even be able to trade for the 3.1.

6500 miles on a good rebuild is a good selling point for the 2.5, but it's not convincing to me as a good reason to put it in a 3rd gen.

Atilla the Fun · 10-14-2009, 02:20 PM

yes, you'll need the S-10's engine harness to connect the S-10's computer, the V6 computer and harness won't work. Most salvage yards will sell you a 2.8 for under $150, however.

five7kid · 10-14-2009, 02:45 PM

Only reason I recommended a used 3.1 instead of a 2.8 is the 3.1 was a step up in design, quality, and reliability. Which is part of the reason a 2.8 can be had for $150.

mikey88firebird · 10-15-2009, 03:53 AM

I was just thinking outside the box I guess. I love the 2.5 and have always wanted an 82-85 2.5 FBird I just can never find one,So why not build my own? My biggest hurdle is how to rewire my car to use the tbi, I would love to do that, and Im a pretty good Mechanic, I have no idea what to do once I pull the v6 engine harness and computer out, will the Birds dash harness just "plug" into the s10 ecm or am I going to need to do some splicing? Any and all help would be greatly appreciated and welcomed! I love the benefits of efi/tbi and am willing to learn how to get it to work in my Bird so please be patient with me!

berlin305 · 10-15-2009, 05:15 AM

IMO 3.1 is junk. rather have the 4.3 imo. But ecm harness just plugs to the battery to the computer and to the tbi and its components doesn't hook up to the main harness at all.

Atilla the Fun · 10-15-2009, 09:09 AM

a '90 3.1 is no better an engine than an '89 2.8, just a bigger bore. No other changes. But you're looking at a rather simple deal with the wiring.

mikey88firebird · 10-15-2009, 02:44 PM

tell me what to do with the wiring, how much of the s10 wiring harness do I need and isit just the engine harness or do i need the harness that plugs into the fire wall that goes to the fuse box on the drivers side too. Ive been looking at the electrical threads and doing searches but havent found a whole lot for tbi just TPI swap so any ideas about threads ive missed please im all ears!

five7kid · 10-15-2009, 07:01 PM

Quote:

Originally Posted by Atilla the Fun

a '90 3.1 is no better an engine than an '89 2.8, just a bigger bore. No other changes.

There were changes to the 3.1 block casting that eliminated a lot of the problems 2.8's had.

Atilla the Fun · 10-16-2009, 11:27 AM

first to kid, I apologize, I was thinking of the 3.1 to 3.4 change, the 3.1 was a longer stroke, not a bigger bore. Yes, the 3.1 did get some revisions. As to the woring, You obviously don't need the headlight wiring and the horn wiring, but grab all the S-10s underhood wiring, including the connectors. Better to start with too much than to be missing something.

mikey88firebird · 10-19-2009, 02:56 PM

well I found a 87 2.8 that was a Jasper engine ,I think, the paper work is in my T1000 and it is cold outside

The good news is his son had thrown a rod in his 92 s10 2.5 so naturally he wanted my engine ( It helps when your cousin is a dumb@$$ and always gets what he wants from Daddy)

NE ways thank you

guys for all your input I think this will be a lot easier like 57 kid said.