I am rebuilding a 455 to put in my GS over the winter. I want to take the numbers matching motor out. I am just wondering if I should rebuilt my manual transmission. It shifts good and I don't really think it needs to be rebuilt, but on the other hand I don't want to put the new motor in and then have the transmission break. I plan on putting aluminum heads (fully ported) on the motor with approximately 10.7:1 compression with a decent sized cam and a B4B intake. Will my transmission hold up with this kind of motor? I have also read that you can get a different casing for the transmission so the original case doesn't crack. I was planning on doing that to the transmission, but I would like some opinions from other people before I decide to do anything to the transmission.
There are 2 ways to beef up a Muncie 4 speed: 1. Masiero gears - these are made in Italy, and are really high quality 2. SuperCase - This is a cast aluminum case that is much stronger than the GM cases I went with the Masiero M22 gears in a clean M21 case. The gear whine is absolutely awesome! :TU:
If you have a good transmission in the car that shifts good, leave it alone and put it to the side with the engine. Original Muncies that will hold 4th gear and not grind 2nd are hard to come by. Buy a used Muncie the needs rebuilding, build it with the better gears and run it behind your hot engine.
Also there is a iron midplate and heavy duty tail section now for the Muncie 4 speed. Also a new side cover with roller bearings is available.
