hey guys i found a 87 firebird that i am planing to go take a look at this weekend . all i know about it so far is . its a 2.8 and its auto. are the 87 cars carbed or efi ? and is the trans a 700r4 ? does anybody know the rear gear ratio that comes with the 2.8 auto trans combo ?

thanks .

 

if you go to the home page, in the firebird tech section, it will list it all for you

https://www.thirdgen.org/1987-pontiac-firebird

i think it shoudl be fuel injected, no carb

 

They switched to fuel injection in '85, transmission should be a 700r4, and you probably have 3.42s or 3.27s for gears.

 

I think my 91 has 3.23 for gears, confirmed by that online vin decoder, can't rememebr the name right now. Let us know what ya find out when you look at it

 

The 87 had MPFI, and has 3.42 gears, unless they've been swapped out (may be 3.23, I guess, but it's still an open diff). The trans IS a 700R4, and is slightly more built than the earlier 700R4 trans (couple different clutch plates in spots), but is not as good as later model 700R4s. You'll want to hear it run, of course.

 

yeah i will let you guys know what i find when i go look at it !!
as for power (with out a motor swap ) what can be done to get a bit more out of it ? will going to a carb set up get me more ? i like old school stuff better so i was thinking a edelbrock intake and holley carb . are the crane gold roller rockers still availble ? and are they worth it ??

thanks

 

Look at the stickies for the Hybrid swap... Just swapping the intake and cylinder heads to a small-port 3100 set gets you around 30 HP... But you'll also need pistons and a computer tune (the stock 2.8 pistons, IIRC, according to a couple of calculations, net about 12.8:1 compression, I think... I'll check). There really isn't much you can do with a carb on these engines as there isn't much of a selection of intakes (and I don't think there is any at all for the Gen III heads). As for the rockers, you might need to look a bit for them.

 

Him and I differ on the use of dished pistons We'll have to compare gains and run quality after we finish,lol.

 

Going carb will lose you power, even with a Edelbrock intake. There are lots of little bolt ons you can do to these engines that'll get you more HP and torque, or go the 3X00 swap way.

 

2.8L MPFI 60* V6 135HP 175FT/ILBS
THM700-R4 Auto Transmission
3.27(GM was using the Borg Warner Gears for this year, 3.23's were in house, starting 1990 and on)
10 Bolt 7 5/8th Open Differential

Vin should look like this:

1G2FS21SXXXXXXXXX

1-USA
G-General Motors
2-Pontiac
F-F-body
S-Firebird
2-2door
1-Manual Belts
S-173CI 2.8L V6(LB8, 87-89)


Hope that helps

 

Hmm, so before 1990 GM was using 3.27 Borg Warner gears, interesting...

 

Thats what I read in a tech article, they switched from 3.27's('89) to 3.23's('90).

 

Stock 2.8s put down 175 ft lbs?

 

GM used the 10-bolt on all V6's. The BW rears were only on V8 cars.

 

The 3.1L stock puts down 180, and I'm pretty sure(correct me if wrong) that the 2.8L pretty much makes 5 less HP and 20 less FT/ILBS. Very simliar engines.

So no I'm sorry, its not 175, its 160.

And maybe the Borg Warners were only on V8 cars, but isn't the rear end still a 3.27?

Its something really close to these numbers.....

 

huh, I've only ever seen the 2.8s listed at 160 ft lbs, though I suppose our cars breathe a little better than the others might...still seems a tad higher than I'd figure.

 

Ugh... so much wrong info. Base 2.8 was rated 135/160. Gears were as I listed above (the car is an 87, just like mine is). The T5 for that year had the higher first gear and lower overdrive gear (4.06 first and .76 overdrive, not that it matters with the auto) than the even 80s years got (2.76 first and .78 overdrive). The 2.8 didn't need or get the Borg-Warner rear end. If the guy gets the car, he can verify this by looking for the axle build code on the front of the passenger's side axle tube (front of the car, not looking at it from the diff cover side). If the gears haven't been swapped and he has a 2HL axle code, it's got a 3.42 ratio in there, with a peg-leg.

---And it's not that we differ on the use of dished pistons, it's the dish size where we differ... There is no doubt that you need dished pistons on the 2.8 when you swap over 3x00 heads. Without the dished pistons, according to simulations, the 2.8 pistons will give a 16:1 CR. I'd personally run a minimum of 3.1 pistons with a 12cc dish to bring that down to 12:1. Ideally, with FI, I'd probably run an 18cc dish (10.6:1 CR).---

 

My Calculated static CR is 12.89:1, its high but not anything like 16:1, which I agree is hands down too high to use. 12 CC pistons would drop me down to 10.13:1 static.

 

We'll save that for 60Degree...

 

PM sent on the other side.