what gear to use

[85 Cutlass Brougham]

What tires and what trans are you running? My gut tells me a 3.42 is the best gear for your combo. I forget the actual cam specs for that cam, but the rest of your combo tells me it probably still makes a fair amount of low and midrange torque, so you really don't need too much gear unless you have tall tires or are using the car mostly for drag racing. I have 3.23's and love them, btw.

 

[mebe007]

Cam Specs:
Basic Operating RPM Range: 1,500-6,500
Intake Duration at 050 inch Lift: 234
Exhaust Duration at 050 inch Lift: 244
Duration at 050 inch Lift: 234 int./244 exh.
Advertised Intake Duration: 308
Advertised Exhaust Duration: 318
Advertised Duration: 308 int./318 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.488 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.510 in.
Valve Lift with Factory Rocker Arm Ratio: 0.488 int./0.510 exh. lift
Lobe Separation (degrees): 112

tires right now are 215/65/R15 i need to get wider ones out back, im thing 255/60/r15 (will they be shorter than the fronts or taller or same size?)
transmission is a Th350 with a full manual reverse pattern valve body[/u]

 

[Mikes455Wagon]

Well, based on the cam, it will probably be quicker with the 3.73s. However, have you checked the price of gas lately??? Given that bit of info, I would run the 3.42s all day long unless your trying to do alot of heads up racing.

 

[mebe007]

well the car is not a daily driver, mainly a weekend warrior once complete, you know cruise to the local shows, occasionally take it to the track. so now its narrowed to 3.73 and the 3.42. also should i just get a factory set of gears that are in good shape since it is the 7.5 or should i look into motive's or richmond's? keep it coming guys. thanks

 

[85 Cutlass Brougham]

With the 3 speed TH 350 you will be happier with a taller gear like a 3.42 or a 3.23.

 

[Nightmare388]

I'd go with 3.90. You will appreciate it at the strip and it is decent for the street. If you run strictly street then go with the 3.73. Just my 2 cents. worth. 4.10 a little to much for your setup. You might be disappointed with 3.42 at strip so I would stick with 3.73 or 3.90.

 

[mebe007]

well i definitely will not go to a 3.23. so its still between the 3.42 and the 3.73 keep it coming guys. also can anyone answer that tire question for me about the rear tires? i have 215/65/15 all the way around i want something like a 255 on the rear but don't know if it would look right if shorter than the fronts, what do y'all think. is a 255/60/15 shorter or taller. also will that fit on a 15x7 corvette rally wheel on my car?

 

[Nightmare388]

well i definitely will not go to a 3.23. so its still between the 3.42 and the 3.73 keep it coming guys. also can anyone answer that tire question for me about the rear tires? i have 215/65/15 all the way around i want something like a 255 on the rear but don't know if it would look right if shorter than the fronts, what do y'all think. is a 255/60/15 shorter or taller. also will that fit on a 15x7 corvette rally wheel on my car?

If the choice is those 2 stick with the 3.73.
A 255 x 60 x 15 would look great in the back and yes it will fit a 15x 7 wheel. Here is my 255 x 60 x 15 BF Goodrich Radial T/A tires on my 15 x 7 Eagle Alloy wheels. They are on my G Body 1978 Monte Carlo. They fit good with room to spare. I have 15 x 7 all the way around. I don/t remember the tire size of the front tires but the are the smallest BFG's I could get to fit a 15 x 7 wheel.

 

[mebe007]

http://www.discounttiredirect.com/direct/brochure/info/tmpInfoTireMathNS.jsp
according to this site the 255/60/15 is .52'' taller than the 215/65/15 and 1.58'' wider. i dont know if i could squeeze any wider under the car thats for sure.

 

[mebe007]

i have a chance to get a compete 7.5'' rear with posi and 4.10 gears for $50 what you guys think. im worried the gears will max the cam out to soon, please help. the rear is complete from drum to drum, the guy put in a 9'' and tis rear is in great shape. also what is a good price on gears and full install kits for the carrier and gears?