Transmission Vacuum Hookup?

It should be hooked up to manifold vacuum.....but some ports on a carb are manifold vacuum.

if ur not on it a c4 is set to shift at about 5-8mph to second, its in the manual and 2nd to third at about 12-15 or something like that, if you are pokeying around

You can adjust where and how (hard) the transmission shifts by pulling the hose out of the transmission and adjusting the screw inside the hole...I can't remember which way you turn it to get harder shifts and farther up the rpm range...

when I first drove my car after the engine buildup, my tranny wouldn't shift below 3500

C-4 Transmission

I think the C-4 is one of the best transmissions you can put in a classic stang. Ford just didn't know how to tweek it just so. If you really want to get setup and your automatic type-o-guy:

ASIDE: An automatic transmission set up properly and the exact same car with your 4-on-the-floor will win EVERY TIME.

That plud aside, I have a 64.5, 289 with about 425HP @ the fly wheel. A standard c-4 would wear out pretty quickly the way I drive so..........

1. Get rid of the modulator altogether.
2. Replace the valve body with a full manual reverse
3. change the splines to stainless
4. Non-decompression first
5. based on your cam and weight, set the stall somewhere in the 2400-3000 RPM range.

You tires will bark just shifting into second with very little effort. The shift is tighter. (I tried the B&M hammer with the heaviest duty cable the made and I still stretched it. A c-4 with these mods runs about a much higher PSI and cable shifters just stretch.

CAUTION: If you do go to a cable shifter be VERY careful. Reverse comes off the high gear and if you over shift third (cable stretch or poor adjustment) you will go into reverse. I did this about 2 years ago at 40MPH. Ever do a 360 in monday morning traffic at 40MPH in the midddle of the street. I cleaned my shorts out I can tell you that.

But we digress, My tranny will handle 600HP+...gotta have margin, has the same weight as an original C-4 (weight = HP lost in fighting physics), and will make every other performance mod better. A manual shift and non-decompress auto tranny is a real kick on the street. You get the control of a manual transmission without the need to coordinate two feet, a hand, and drive the darned car. The non-d 1st gear is really cool. without load 1st gear free wheels and the car goes to idle and a psuedo-nuetral. When you punch it, the torque converter locks up and if your stall is at 2800 and your running a rooler motor or roller rockers the instaneous power to the real wheels is outrageous. the converter slips to get you into your torque band so within a fraction of a second from what the guy next to thought was a manual car in nuetral your at the RPM, GEAR, and MAX Torque....It's the best performance and fun driving mod I have ever made.