Hey, finally got the car running smooth, however it seems that it is shifting through the gears to fast. i would guess its in first from 1-20 mph, then 20-30 is second, and at 30 it shifts into 3rd. this just doenst seem right to me, and is wierd on the freeway. is this normal, or should there be somethign i need to fix i have already replaced the vacuum modulator. also, i feel like when i put the pedal down i am not getting everything out of the car, i pulled it manually on the engine and it reved higher, is there some sort of linkage that could be the culprit, let me know
With the motor off, have someone press the gas pedal while you look into the carb with the air cleaner lid off. See that the throttle opens all the way. Maybe the throttle cable is binding, or the bracket that mounts the cable to the intake manifold is bent or mounted wrong. If the throttle doesn't open all the way, it is possible to make the tranny act like you describe. It will never see full vacuum, etc.
Is your kick-down linkage on and adjusted? It should have .060" gap when at full throttle and the kick-down lever is pressed all the way toward the transmission. Your shifts are a bit late if it is shifting 1-2 at 20mph and 2-3 at 30mph. A good street C4 will shift 1-2-3 before you get across the intersection. If you have a street / strip car then the shifts should be just a bit later than that with the 2-3 shift at about 20-25. This is all with light throttle, with heavy throttle 1-2 shift should be at 4400 rpm, and the 2-3 should be at the same RPM. Late shifts cause wear under light throttle. Under heavy throttle the C4 will shift later.
I interpreted this as when it shifts at full throttle. If it is shifting this high at light throttle, then there is something else going on.
Yep! if it is shifting that high at light throttle then you might have the wrong vacuum modulator, a rod that is too long between the modulator and the modulator valve, not enough timing advance, lumpy cam or a leak in the hose or metal tube that supplies the modulator with vacuum from the engine. If the kick-down rod is being held down part way that could also cause the problem. The street, stage 1, transmission that I just built for my wife (a $900 retail value C4) shifts through all three gears before you cross the intersection and you never feel it shift. The shifts are very fast and at very low speeds. That is what is best for the transmission. Hers is a pure stock V-8 (210 hp 302) with a C4that is built with all the good parts to take 500+ HP. I never want to have to build her another tranny and if we maintain it properly I never will. Now if, as you interpreted it, this is at full throttle then the governor is faulty or the modulator valve is stuck or the rod is too short or the modulator is the wrong one and/or the kick down is not operating. There might be other valve body problems but I am not going to go into that here.
