Is this possible or not

[mach123]

Hi everyone, I was woundering if I have a 3 speed tranny 727 and building a 512 stroker and will be going with a SG 3.55 hoping to find one, and I want to know if it is possible to make a 4 speed with this tranny so I would have over drive or should I look for a 3.23 and stay with the 3 speed 727 tranny. Thx for any info on this.

 

[Kern Dog]

Make a 4 speed?
About the simplest way to get another gear is to use a BOLT on Gear Vendors overdrive. The trans tailshaft is removed and GV supplies an adapter to bolt on their unit. I have one in my 70 Charger. Great unit.

 

[747mopar]

X2

 

[Montclaire]

GV unit will leave you with a shorter drive shaft and that can be an issue with some wheelbases. You can install a 518 with a lockup converter but that requires big time surgery to the floor pan and trans crossmember. Keisler makes a four speed auto that bolts right in but it ain't cheap.

 

[Meep-Meep]

With a 512 stroker you can probably push 2.94's with a 3 speed, but you better have some good drivetrain components. Build the motor for low end / mid range grunt (long lobe separation cam like 114) and enjoy high idle vacuum, a pretty smooth idle, clean running and easy to tune. Also major burnouts on demand.