Hey, I just have a few questions regarding putting a 3.1 from a '91/'92 (can't remember) camaro into my '85 firebird. Originally had 2.8 but one of the pistons got a hole through it and the metal chunk lodged itself into the head. I have the aforementioned 3.1 available and just needed to know what I'd need to look out for and what will fit/bolt up and what won't. I'm broke, and can't work till I get this thing on the road and don't have a lot of options. Any help is greatly appreciated. Some of the questions at hand are will the transmission bolt up? Should I use the computer from the 3.1 (Sounds like a stupid question, but I'm not very knowledgeable)? Can my 2.8 wiring harness be made to work? What about Y pipe.exhaust? Again, any help is greatly appreciated.

 

Your thread will probably get moved to the V6 Board, soon, and that's where you need to be. You'll get a lot more help over there.

You'll use the 3.1L V6 long-block and swap it underneath your current intake manifold set-up. Everything else is virtually the same.

 

This ^ 3.1 from oil pan all the way to lower intake, if you wanted to you could even use the whole motor, but there would be little nitpick things you would have to alter. You retain stock engine harness, electronics, ignition system, fuel system, etc. Just make sure to use the 3.1 injectors, and retain your cold start injector if you had one originally.

 

u will have to put the intake form the 2.8 on the 3.1 due to the cold start injector setup and the difference in the throttle body.

but other then that it bolts right in

if u wanted to u could just bolt the whole 3.1 in as is but the car wont run right when it first starts up when its cold, once the motor warms up it would run normally

 

Thanks a lot guys. You have all been a great help. Hopefully I can start moving forward with my life now then if this all works out. Thanks again!

 

Not quite, there are other minor differences, namely vacuum lines and TB(IAC routing is different), they can be worked around with relative ease though, but its not a 100% bolt in ordeal, I know this because I had a 3.1 upper on my car for a brief spell. Just wanted to make sure he knew that before he delves into whichever route he goes. Another thing to watch out for is whether either car had cruise, if his 2.8 had cruise and the 3.1 did not, he is going to want to keep the 2.8 TB, which means keeping the 2.8 upper intake.

 

I apologize for my newb-ness, but what is TB? and what if the 3.1 had cruise? I don't think either engine did tho (assuming I'm right in guessing cruise control?) Also, just found out the 3.1 car had digital speedo, mine does not... does this matter? (In terms of mine running off of a cable, and me not knowing whether the digi does too or uses like a sensor or something?) ^.^; again, sorry for not knowing Jack...

 

Throttle body, the linkage on it could be different, speedometer doesn't matter, has nothing to do with anything you are doing. It is a cable from the transmission to your speedometer gauge, it could care less what engine is turning it. As long as you aren't swapping gauges or transmissions, or running taller/lower tires its not going to be affected by anything.

 

Lol, now I feel stupid... I definitely knew that too. Thanks for the answers though, this place is great.

 

Don't mean to be late, but there are things that need to be clarified... Someone needs to write a guide or something on the differences between a fuel injected (non-TBI) 2.8 and 3.1...

TB on a 3.1 will work fine, physically (assuming you keep the 3.1 TB with the plenum as the 3.1 TB will NOT work with the 2.8 plenum due to revised IAC passage routing). It's the WIRING that is different. The pull cables for the cruise, transmission, and accelerator pedal and bracket are the same. The IAC wiring and TPS wiring are not. The other difference between the 2.8 and 3.1 TB is that the 2 vacuum lines on the 2.8 vacuum block (where the lines connect to on the top of the TB) need to be switched in the block and the 2.8 block used in the 3.1 TB (manifold and ported vacuum ports are reversed between the 2.8 and 3.1 throttle bodies). And if you're going to use the 3.1 upper plenum and TB, you need to retain the 3.1's stock PCV valve pipe and find a way to connect the charcoal canister to the 3.1's vacuum system (could just plumb the hose right to where the MAP sensor bung is on the left rear of the plenum since you don't use the MAP on a 2.8).

2.8 and 3.1 used the SAME FUEL INJECTORS. Actually, the 3.1 runs .7 lb/hr SMALLER fuel injectors than most 2.8's (with the 523-5210 injectors and not the 14084888/similar, 523-5210 2.8 injectors having a 15.4 flow rate and the late 2.8/3.1 84888s having 14.7 lb/hr rate). Difference is in the 7th injector the 2.8 had with the different cold start calibrations.

Most pre-87 2.8s used a V-belt accessory drive. The 3.1 uses serpentine. The water pump is NOT the same as it is turned in the opposite direction. The water pump should be replaced on a junkyard engine anyways as who knows how long it has sat without the bearings and seals being lubed by coolant (mine failed within a month of being installed).

You need to either keep the flexplate (part that the torque converter bolts to) or the flywheel (manual transmission) on the back of the 3.1 for your setup. You CANNOT use the 2.8's plate as pre-88 2.8s were externally balanced. You will shake the lower end out of the engine if you don't check this.

Regasket the entire engine from top to bottom while it's out. And also a new pair of main seals on the timing cover and the rear.

 

I did it!I used the 3.1 and left the lower part of the plenum on it and took the plug for the 7th injector out and put mine off the old motor in.Left the old 2.8 injectors in my mix.that way I didn't have to cut the harnessand splice in the 3.1 injectors.no big deal either way.I left the sepentine belt setup and changed my altnator conector.But I dont have a guege light working because the original has more wires.Used the 2.8 upper plenum and throtle body,also took my oil filter mount with sending unit for gauge and fuel pump wireing off the old engine and put them on my replacment.some otheres also so I could keep as many conectors on the harness as possible.

 

Actually, to avoid having to swap over the entire oil filter adapter, all you needed to do was to take the plug out of where the 3.1 OPS screws into the adapter (there is a 1/4" plug above it that's probably covered in crud) and put your gauge sender in the open hole .

 

oh you will also have to use the oil pan that came with the v-belt system or use the oil pan that came with the serpentine system. The v-belt has a lip on the bottom and won't match up with a 3.1

 

actually its where the oil pan and the water pump meet. oops