Pontiac Firebird 1967-2002 - Gears upgrade on 305 tpi

Hey Gents!

My current car and daily driver is an 85 trans am A4 TPI...

I have a set of 2 series 3.73 gears laying around and seriously thinking of upgrading my stock gears with... Im just looking for a bit more of "seat of the pants" performance out of the car...

Im just wondering, ive been reading around and heard that TPI engines are VERY VERY hard to tune...

Is that true? If so, i was wondering whether or not i could bring my car to a local dyno jet and calibrate my speedo with the newly installed gears?

Another question, is there a gear calculator for 3rd gens out there? Im wondering what RPM would my T/A would idle at at 70MPH with 3.73's


i need all the feedback i can get, thanx!!

Thirdgen speedometers can't be adjusted via computer like an ls1 car. You have to change the speedometer gear which is in the transmission. I did it a long time ago when I had my 91 camaro and it's not hard. Here's some good info on it: http://www.thirdgen.org/techboard/transmissions-drivetrain/528418-sticky-700r-4-speedometer.html The second link in post #9 shows you what you have to do.