what should i put in my 1981 camao

 

for drag or fuel saving??

 

A little more info about the car would be nice, maybe add a signature telling everything about the car.

 

i just bought a 355 for my car it came out of my buddys 72 camaro with a th 350 with shift kit and 3500 stall and 4.56s the car went 11.40s 11.50 all motor now the only diff is my gears and my tires and i am going to spray it with a 150 shot i am running a mt 275/50/15 et street deag raid so what do you think i should go with for gears i am thinking 3.73 or 4.10s

 

If quarter mile performance is your priority, then here's how you figure out which gears you want. You'll need a calculator.

1. Determine the maximum RPM you are willing to run (example, 6000)
2. Multiply by your tire diameter in inches. (example: 25.6")
3. Multiply by 0.002974993.
4. Divide by your desired trap speed in MPH (example: 120).
5. Get a set of gears with the next available ratio lower than the number you came up with in step 4.

Using my example numbers, you should come up with 3.814. The next available lower ratio is 3.73, so that's what I'd get. Do the steps with your own numbers and you'll be able to figure it out on your own.

In case you're wondering, the constant in step 3 is equal to pi * 60 / 63360.

If you don't know your tire diameter, here's how to figure it out from the tire spec:

A tire spec looks like this: P275/40R17.

275 is the section width in millimeters.
40 is the sidewall height as a percentage of section width
17 is the wheel diameter in inches

1. Multiply the section width by the sidewall height. (275 * 40)
2. Divide that by 1270
3. Add the wheel diameter in inches (17)

In my example, I get the 25.6 that I used in my previous example.