Two-Speed Shuffle

Replacing a Powerglide With A TPI TH350 Is a Smart Step

Every Chevy II Nova owner in the world knows the feeling of a "slip 'n' slide" two-speed transmission. That's because the only option with those early cars ('62-67) was a Powerglide, unless the original owner opted for a manual trans. The 'Glide offered a simple solution for these economy cars, but when it came to performance, they lacked street driveability under virtually every condition short of a big-block under wide-open throttle. Even with a rebuilt box in a small-block car, the tall gearing made the combination seem underpowered. The best solution for those wanting to conserve cash and stick with an automatic is the installation of the venerable Turbo-Hydramatic 350.

Our donor car offered the perfect opportunity to swap out the Powerglide with a custom-built 350 from TPI Performance. With close to 400 hp on tap, this little drop-top has plenty get up and go. Still, it was sluggish out of the hole and took a while to climb into the powerband with a Powerglide in the tunnel. Not only that, the rpm drop between First gear and High took the potent Mouse out of its torque range. A three-speed was just what this little Deuce needed.

TPI's Turbo 350 has much shorter gearing than the Powerglide. And adding the extra gear will give the car more momentum off the line that will carry all the way through the entire powerband. The best part about this swap is that it will enhance the overall driveability of the street machine. With less rpm drop between shifts the engine will maintain its torque and be more responsive when the throttle is mashed. Likewise, when cruising in High, since we didn't change the rearend gearing, the car will still be comfortable at highway speeds.

Installing the TPI TH350 was a relatively simple swap, since, dimensionally, it is the same as the Powerglide, which meant we didn't have to shorten the driveshaft or beat on the transmission tunnel. There were a couple of things we did have to convert, however, such as the shifter and the crossmember. Additionally, we had to run transmission cooler lines, since the TH350 routes the fluid to the radiator for cooling while the Powerglide relied on air to cool the transmission fluid. Another part of the swap was made easier by using a fabricated crossmember from Chevy 2 Only. A stock crossmember will work, but there is a small amount of modification that needs to be done to the leading edge. For the average do-it-yourselfer this isn't a big deal, but if you want a nice piece that simply allows the tranny to bolt in, go for the Chevy 2 Only part.

Since early Novas never came from the factory with a Turbo 350, there were no three-speed column shifters. In order to keep the factory column shifter, we used a special kit from Lokar, which consisted of a trick linkage arm for the transmission and the necessary rod and ends to connect it with the column mechanism.

Keeping with the performance portion of the swap, we installed a torque converter from TPI that had a stall speed of 2,800 rpm. This was the perfect combination to the firm shift that the trans provided. Now all the car needs is a Posi rearend.

In summary, with all the right pieces from TPI, Chevy 2 Only, and Lokar, our little Deuce retains that original look and takes on an added dimension of performance.

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