Help with rear end ratio

[bubblefeak02]

I have a 1978 pontiace firebird with 350 small block with 350 horse and 400 foot lbs tourque. I have a TH350 3 speed trans with 25.5 tires. I'm looking for a good street/strip rear end gear ratio. Something i can drive back and fourth to work and take to the strip on friday nights. I need something better than the 273 in it. before my engine upgrade to the current specs i was running mid 16's at the track with a stock 350. I need a good ratio that will work well with my current power and not eat me alive in gas and not sound like a air plane going down the road. I've thought about the 3:55 or 3:73 but thats just my unexpereinced guess. Any thoughts on the subject would help.

[Matt167]

Well, we need more info, was the 25.5 tire used when you ran 16's? If so, then 3.73's would be good, if not a 4.10 ratio would be better because the bigger tire than a stock tire, will decrease the final ratio, the 4.10 would compensate for the raito loss and end up being around a 3.73 or so, to get a true 4.10 which I doubt you would need or want because of some streetability issues on interstates and such, you would need a 4.27 raito.

[deepnhock]

I'm running basically the same combo as your car...
I run a 3.55 rear gear and like it a lot, except on long trips...
Seems the engine combo I have is 'happy at 3100 to 3300 rpm and that equates to about 72 mph... I ran a 125 mile trip Sunday to a car show
(see pic's at:
http://community.webshots.com/album/384945224IqjTtC

Got 16.8 mpg.... Not too bad...

4.11's were fun...in town only...

Hope the info helps...
Jeff

[pro70z28]

I ran 4:10 in the panel truck. Drove it al over the country. Longest trip was 2 days each way........ pullin' a camper no less. It was great ............. Little hearing loss, but other than that it was great.