Rearend Gears

[Mhelle13]

What's your guy's recommendation on a good rearend gears for the street? I have a 340 with a 3 speed auto. The motor is fresh, and dynoed a little over 300 hp. It has trouble with fast acceleration (seems like a turd....) could this be something different gears could fix?

 

[challenger6pak]

Possibly. 3:23 or 3:55's work well.

 

[Adam]

What is the current ratio? if you already have the common 323s an Aftermarket stall converter and valve body will really wake it up.

 

[Mhelle13]

I'm not sure what I currently have. @2500 rpms I'm going 58mph

 

[djais1801]

I have 355's in mine, but mine is a 4 speed manual

 

[mmissile]

By today's standards, most old, smaller displacement muscle-cars are gonna feel slow. The convertor will make a big difference, also.

 

[Adam]

I'm not sure what I currently have. @2500 rpms I'm going 58mph

Jack it up turn the wheel/tire one time/ revolution and count the number of driveshaft turns; 3 1/2 turns would be 3.55s, ect...

You may have to block or hold the non drive wheel if you have an open diff.

 

[moparleo]

Here is a calculator to help you figure what you want for gear ratio depending on the rpm power curve on your dyno sheet. http://www.bgsoflex.com/rpmmph.html http://www.wallaceracing.com/calcmph.php

 

[Chryco Psycho]

THis is the one I use , Mopar dashboard !
http://vexer.com/automotive-tools/speed-rpm-calculator
Using this with a 255/60 tire 2500 RPM is 58 MPH

 

[moparlee]

THis is the one I use , Mopar dashboard !
http://vexer.com/automotive-tools/speed-rpm-calculator
Using this with a 255/60 tire 2500 RPM is 58 MPH

That Mopar Dashboard calculator is way cool!

 

[AUSTA]

What's your guy's recommendation on a good rearend gears for the street? I have a 340 with a 3 speed auto. The motor is fresh, and dynoed a little over 300 hp. It has trouble with fast acceleration (seems like a turd....) could this be something different gears could fix?

sounds like a 3.55 like MMissles
quote you need to get your RPM up and keep it there using a higher stall & maybe holding gears a bit longer using a modified valve body what is the RPM at full accel at take off & when it changes from 1st to second
Also what carby are you running i found some of the holleys not as responsive on my 340 Auto 376 Hp running 780 CFM quickfuel jetted down with E/Q heads

 

[Mhelle13]

I have a edelbrock carb not sure which model. I have been told a Holley 650 dp would be a better option.

 

[challenger6pak]

Google the stamped number on your carb to find out what you have.

 

[moparleo]

By the way. Was the engine dyno'd out of the car or in the car ? If it was in the car, who ever did the work should be able to diagnose the problem almost immediately. They will be getting a/f readings at all rpms, hp and torque curves by rpm.