which rear end gears to run with my motor/tranny?

[Out_Sider]

well right now my truck has a completely stock 351w in it with a stock c4 transmission, and we think it has 3.25 gears in the rear end now, but not sure. Well anyway heres the thing we are rebuilding and stroking the motor to 393 and having the c4 built. now im curious as to what rear end gear to use with this motor and transmission combo? i was thinking 3.50's, what are ya'll opinions?

[bryantracing460]

What are you planning on doing with the truck? Daily driver, weekend warrior, or all out drag truck? BTW welcome to the forums.

[magnethead]

If you're stroking the motor, your red line will decrease, but your torque output will increase, so using that you could get better speed/fuel mileage by going up to 3.10's, or get lower fuel economy and better acceleration with 3.50's, but on the highway you'll ahve to be more consious about the RPM.

[1968Ranger]

Welcome to the forum from another Carolinian.
Mike

[DuckRyder]

It depends more on the cam than anything else.

You need to calculate what gear will get into the "cruise rpm range" of your cam with the rear tire size you plan to run. It should also be above the stall speed of your converter at normal cruising speed.

In general 3:50 is probably a pretty versatile all around ratio.

[cobraF100]

DuckRyder is right.

We need your:
Cam #'s
Converter Type with stall speeds
Tire size (Best would be the Roll-Out)
*** "Roll out" is the circumference of the tire and measured by pulling a tape measure all the way around the tire.***

Use the "Loaded" way to Measure your Tire size.So do it with the Trucks weight on the Tires.

Here's a Link to help:
http://www.mickeythompsontires.com/tech ... llout.html

also need to know what you plan to use the Truck for.