Turbo 400 experts please step in....

[joespanova]

Originally Posted by Greg Reimer 7376

Seems that the factory had its work cut out for itself fine tuning this trans to fit all the various engine combinations it found itself behind. The basic three speed planetary gearset came behind 250 horse 327's up to 400 horse plus big blocks, plus Pontiac,Buick, Olds and Cadillac, all high torque motors with various characteristics. Vacuum modulators, modulator steel line sizes, and all kinds of valve body springs all went together to make this trans work for everybody. A certain amount of trial and error is to be expected in order to fine tune it to suit a particular user. Of course, most drag cars have a manual valve body so modulators and other spring applications turn into a moot point . The age old axiom is correct here when we find that the best dyno is the drag strip. Sounds like an assortment of modulators and springs and a trip to the track for a test and tune session would be your ultimate best bet. Just don't change anything on the engine's state of tune while you are working on the transmission. Good luck on your project,thanks for introducing a subject that resulted in quite a bit of intelligent discourse.

Recall , this thread is only about part throttle early shift 1-2. But good points.......