I bought my 85 trans am a few years ago without an engine. Finally I'm getting around to getting a 305 put it. There it a lt1 t-56 for sale locally that i would like to get and drop in. Also would like to swap out my 3.08 gears in my 9 bolt for some 3.73's. stock tires, stock suspension. T-top car. The 305 came from a 81 c1500 and has a quadrajet 4 bbl.

What kind of performance can i expect out of this combo with a decently tuned engine? I'm sure it will be no tpi 5.7, but thought i would pick you guys brains.

croozer

 

Great transmission... crappy engine.

 

150hp at the crank, brand new and running perfect, back in 1981.

Honestly... just keep looking for another motor!

 

I bet with a good launch you could pull high 17s

 

Depends what u want ... the 6 speed is a great idea as well as 3.73 gears .. shock both should wake it up but with the 6 speed I would go with 4.10 gears without even thinking about it ... I have 4.10's with stock 5 speed and on only pulling about 2400rpm at highway speeds so u would b closer to 2k which is perfect IMO .... but I'd atleasr put headers cam & intake on it with a good exhaust system before i put that motor in ... better yet find a 350 .. or atleast a newer 305 ... ... u will prollg b highly dissapointed in that stock 305 no matter what drive train is behind it.... hell the 3.8 V6's are 200+ hp

 

And just for an idea .... my Bone stock 305 TBI 5speed firebird ran an 11 somethin in 1/8 when I got it with one tire fire and 3.08 gears .....

After 1.6 RR ,TBI spacer, exhaust (no headers) , it was at high 10's

Then I got a used rear end with new posi 4.10 gears , UMI torque arm, CFM tech 620cfm TBI, fuel pressure regulator , and EBL flash w/ WBO2 and tuned it and I ran a best of 9.802 @ 74mph with a crappy 2.1-2.2 60 ft spinning pretty bad ... so with better tires I believe it would been good for 9.5-9.6 1/8th mile ...

Now I'm shooting for 8 second flat on motor with the 305 (far from stock)

Oh and that's a 1991 roller cam 170hp stock 305

 

We all have to start somewhere

 

I'd definitely get new heads, headers, full 3" exhaust. And probably a better cam than what's in it. Carcraft and Chevy High performance both did a 300hp 305 build. If you're stuck on the 305. Otherwise 350 is a no-brainer. Especially since you haven't installed the motor yet.


Is your 85 a TBI or carb'd car from the factory? Or TPI?

Also, where are you? Do you need emissions testing done where you're at?

The 6 speed and 3.73's will cruise nice and easy on the highway! Would be an awsome combo.

 

My 83 G20 went 11.20s @ 66 mph with the stock 601' head 305. Had swapped over to a TBI intake, 204/214* @ .050 cam, and tri-y headers. I would go 4.10s with the 6-spd. It would still cruise very nice in 6th.

 

All the manufacturers are using multi-speed transmissions to optimize their engines operating range, no reason you can't do the same. The engine will still be a stone, but if you have decent exhaust at least it will be fun to row more gears. Then if you like the car you can build on that platform.

 

The OEMS are using multi-speed transmissions to increase fuel economy.

 

Which is why the T56 has two overdrive ratios; the T5 only had one
O/d is not a performance ratio