The car is a 1886 trans-am. It has the 305 HO motor with the auto tranny. Me and a friend put a diffrent carb and distributor on it. The carb was a factory qudrajet the (NON-electrical) type off of a 350. The distributor is also a (NON-electrical ) vacum operated type off of a late 70's 350. Well we got it all together, after a lil problem with the timing. It runs pretty good but now it feels like the transmission is not down-shifting when we give it throttle. Does anyone have any idea on what could cause this? Do any of the sensors that we unpugged and are not using any more with the new carb control the transmission? Thanks for your help guys

 

sounds like the throttle valve cable (kickdown cable) for transmission is out of adjustment. it is very important on 700r4 transmissions for them to shift right. Been too long since Ive adjusted one and I dont remember procedure, but Im pretty sure its simple....

 

The purpose of the throttle cable (to the trans) is to tell the tranny how far the accelerator has been depressed, to assist it in knowing when to shift (or downshift).

If the throttle cable is not pulled far enough during acceleration, shifts will occur too early. (The tranny "thinks" the accelerator pedal is not depressed as much as it actually is.)

If the throttle cable it is pulled out too far during accelleration, shifts will occur too late. (The tranny "thinks" the accelerator pedal is depressed more than it actually is.)

The throttle cable to the tranny is supposed to run through a bracket at the carb (or throttle body, if so equipped). There is a spring-loaded tab (mine's silver) that you push in while pulling the cable housing back. This stretches the cable inside to the max. Then simply get in the car and slowly press the gas pedal (engine off) all the way to the floor. This will automatically pull the cable housing back to the optimal position. The idea is to have the cable pulled just to the end of its travel at WOT.

Don't stomp the gas pedal - just press slowly. Stomping the pedal may result in the housing being pulled back (towards the carb/throttle body) too much, resulting in late shifts again...

 

I thought that was the procedure, but its been so long since I had a 700r4 that I didnt want to tell him wrong...Thanks

 

This is the same procedure used to adjust the throttle cable for the 200-C auto tranny. I had one in the '82 Z28 that I owned before getting the '87 IROC...

PS The computer-controlled Quadrajet 305 engine and 200-C tranny would barely get out of its' own way, and as it was only a 3-speed, turned too may RPM's on the highway. This combo left a lot to be desired...

 

It's a common problem when someone switches to a carb setup. Most people do not know that the TV cable is required on the 700-r4. Not only does it control downshifts like the ones on a t-400 and t-350, but it controls the pressure itself. So without the cable on the 700-r4 you can burn up the trans.

 

After re-reading my response to you, I realized that I described the misadjustment scenarios backwards.

This is what I should have told you:

When the throttle cable (to the tranny) is adjusted too loose (not pulled out enough), the tranny thinks the the accelerator pedal is not pushed down as far as it actually is, so shifts occur too late.

When the throttle cable is adjusted too tightly (pulled out too far), the tranny thinks the the accelerator pedal is pushed down farther than it actually is, so shifts occur too early.

I did correctly describe the proper adjustment procedure (see above).

My bad - Paul