350 Shifting to soon?

[Mertz]

?

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72 Chevy 3/4 ton pickup. I installed a quadrajet and it is working great. I adjusted the transmission cable with the throttle wide open and then connected the cable. I pulled a trailer for the first time today and going up a steep grade at 55 is down shifted up shifted and down shifted several times very quickly. When I got down to 50 it down shifted and stayed there until I got to the top of the hill. It seems to be shifting early without the trailer as well. I have a stock converter and rebuilt trans with a shift kit. Is the cable to tight?

[Dhartmann]

I guess first question is are you running a th350? If so and your trans is not shifting (later), or too soon...then IF it has an adjustable modulator on the trans...(this is the piece that your vacuum line is connected to) you may try removing the vac line from the trans and adjusting the screw inside the modulator..(i believe you turn the screw in to delay shifting, and out for a quicker sooner shift). In your case you would want to turn it in. i would start with 1/4 turn at a time, but should only need 1-2 adjustments at most. If this doesnt work...check and make sure your vac lines arent rotted out/clogged etc..And lastly even though you adjusted your kickdown..it may be too tight not letting the cable slide back into position when you are out of the passing gear. Hope this helps!

[C low]

like the last post!! clockwise on the screw in the modulator will give ya more time between shifts..

[Mertz]

It is a th350 and it did not do this with the Edelbrock on it with a extender the guy before me put on it instead of adjusting the cable on the holder. It seems to be moving fine. It was really odd that it went in and out so fast going up hill. With the other carb set up it would hold in lower gear until the load was off. I will check fuild level and loosen the cable. I'm not sure if my modulator is adjustible. I have the vacuum line connected directly to the manifold on a tee that goes to the heater damper. I was driving the truck during carb testing with the cable disconnected and it shifted different than it does now even without a trailer.

[Dhartmann]

You said you disconnected it and it shifted different....is this different better or worse? Before you go any further i would crawl under your trans, pull your vac line off...you wont be able to see the screw inside the modulator, but use a small flat head screw driver and stick it in the mod...if it catches a groove then it is adjustable. Turn it in 1/4 turn, put the line back on and go 4 a test drive. This has worked for me in the past with a similar prob like yours.

[Mertz]

It down shifts more often with the cable connected. I will check the modulator and see if it is adjustible.