Rear end gears and traction

[Coogsvette]

I have a base model car 1971 270 hp and 336 rear end gears do not know what 4 speed trans.
The 270 hp 350 is gone and zz4 with hot cam went in its place.
.
The reason for my question isI am planing a head swap and rear end rebuild this winter the engine will bee making well over 400 hp 430 torque
The car is just a week end toy do not take it out on the highway very much.
What rear end gear becomes a traction problem.

 

[Curtis]

Ha Ha Ha With that kind of power I would say the gear ratio won't matter much and it will be a head problem directly related to an over exuberant mashing action of the right foot...

 

[Glensgages]

I have a base model car 1971 270 hp and 336 rear end gears do not know what 4 speed trans.
The 270 hp 350 is gone and zz4 with hot cam went in its place.
.
The reason for my question isI am planing a head swap and rear end rebuild this winter the engine will bee making well over 400 hp 430 torque
The car is just a week end toy do not take it out on the highway very much.
What rear end gear becomes a traction problem.

I would think that the size & type of rear-tire will play into this equation.

We recently removed the Cross-Fire from my '82, that had previously been modified with 3.73 gears in the rear, combined with a 3.06:1 First Gear in the 700R4, for an 'effective' First Gear ratio of 11.41:1:
in the CFI's place is a 650 double-pump carb & Holley dual-plane intake.

The car now runs easy 14-flat @ 95+ MPH trap-speeds, with 60' times in the 1.9 to 2.0 range, on rock-hard BFG T/A Radials

 

[Rodney Gold]

3.36 is fine , nice compromise gear

 

[Hib Halverson]

Which trans is in the car has an effect on this decision. Also, where in the power range that engine makes 430 lbs/ft has a bearing on this, as well as....

I
The car is just a week end toy do not take it out on the highway very much.
What rear end gear becomes a traction problem.

I think the perfect set up is going going to be the ZZ4 with a wide ratio trans, 3.55 gears and some good tires. Since you don't care about highway mileage much, that will give the car a lot of performance off the line that you can use provided you have the tires to get the car to hook.

 

[Coogsvette]

Do you all know what trans came with base model cars.
Max torque is going to be 3500 to 4000
I have been thinking about 373s

 

[minifridge1138]

I haven't touched my differential, but a lot of other people tell me the 3.55 is a nice balance of tire spinning and highway streetable.

 

[Koop]

Do you all know what trans came with base model cars.
Max torque is going to be 3500 to 4000
I have been thinking about 373s

You're going to have a hard time hooking up with 3.73's. My car is an Automatic with 3.08's and the tires just fry until I let off the loud pedal. (Michellin Pilots 235's)

I wanted to change to 3.73's when I put in my current motor, but the best advice came from my mechanic "wait and see how you like it, because you won't like the 3.73's".

 

[Coogsvette]

You're going to have a hard time hooking up with 3.73's. My car is an Automatic with 3.08's and the tires just fry until I let off the loud pedal. (Michellin Pilots 235's)

I wanted to change to 3.73's when I put in my current motor, but the best advice came from my mechanic "wait and see how you like it, because you won't like the 3.73's".

That is what I have been looking for

 

[GTR1999]

Your car would have come with a M-20 wide ratio Munice. With that you can run just about any ratio, even 273's if you wanted. With the torque you have just match the engine,trans, tires for the best gear. I would beef up the 10 bolt a bit as well or may find it decides to crack one day of abuse.