Help - Powerglide to TH350, TH400, or M21?

Just a quick question:

I am currently restoring my 72' Nova, and I'm all about swapping out the crappy 250 L6 and the Powergiide trans. I know the splines are the same for the TH350, PG, and M21, and that they would go in without any modification for 68-72 Novas. However, I have friend selling a TH400 out of a camaro, and I'm wondering if it is truly worth it to drop into my Nova. What is the difference between the TH350 and TH400 besides 27 and 33 spline (respectively), and the ratio differences, 2.48 and 2.58? Also, is the conversion to the Muncie M21 just as easy as a TH350 swap (With the exception of obtaining a Z-bar pedal assembly)? Lastly, is a swap to M20 or M22 possible?

Thanks in advance

Swappping to a M22 rockcrusher or M20 are as easy as dropping a M-21 in the car, so yes those are doable. As far as the differences between Turbo 350s and turbo 400s, there are basically two things that most people look at. The first is loss of power through the drivetrain. With a Turbo 400 you can expect about a 50 hp loss going from flywheel horsepower to rearwheel horsepower. In turbo 350s the loss is monr along the lines of 30 horsepower, so you actual save 20 RWHP by using a turbo 350 over a turbo 400 (around 20, not exact). But the downside to that is durability. You can make a turbo 400 practically bulletproof and hard enough to take all the horsepower you can make. With a turbo 350 there are DEFINITELY limits as to how far you can push one. I personally would rip that powerglide out of there as soon as you can in favor of a turbo 350 (especially if you plan to keep the inline 6), or convert to the manual if you have extra money to use. With that extra gears over a powerglide you'll notice a good jump in gas mileage and improvement off the line if built right.

Rob

Thanks alot for the post ROBS71NOVA. I am now deciding on using either a TH-350 or an M-21 (wide ratio), and yes, I will be using the 250ci L-6 until I can build that 900ci blown and bottle-fed monster i've always wanted...

I have one more problem: How about would I go converting the nova from a column shift auto to a floor mounted auto or manual?

For manual: Need clutch pedal assembly (with Z-bar), and I need to cut out the hole in the tranny hump. Where does the hole get cut? Anyone have the dimensions and measurements?

For auto: Older automatics are cable operated, so is the tranny hump cut in the same spot as if I was converting to manual?

Bear with me, I have some knowledge, but i've never made major drivetrain changes...

For the manuals, Im honestly not sure. It seems as if you would have to cut the hole right above where the transmission is under the car, but It may be different so don't quote me on that. I DO know that the M20-22's are basically the same though and will work for your application (because alot of the older Super Sport Novas in our 68-72 body style's had the M-21's). For the auto shifters, you really dont have to "cut" anything. All you need to do is drill 5 holes, 4 to mount the shifter, and one for the detent cable to go through to get to the transmission. I actually just recently purchased a "B&M Star Shifter" off of ebay for 110 dollars and I am very happy with it. If you buy them new the shifters come with all the correct linkage and everything, basically EVERYTHING you need and they arent hard at all to put in. They come with very detailed instructions. I hope this info helps.

Rob