JB46

My 75 will start immeadiately in the morning. I press the accelerator once to reset the choke. Turn the key, and it will start without having to press the gas pedal.

It will go to fast idle which is at 1500RPM. The issue I have is, I can't get it to kickdown by tapping the gas pedal. I can open the hood and manually reset the kickdown cam and get it to it's idle speed of 700RPM.

What do I need to adjust to get this function operating correctly. The Quadrajet has an electric choke, and it runs without any other issue aside from what I have mentioned.

I did search under 'fast idle kickdown' but I'm not seeing this covered. I have ordered a Chevrolet service manual, but would like to address this issue now.

Thanks-Jeff

Steve2147

Is it sitting on the very highest step of the fast idle cam? If so, there are two adjustments you need to check and I can't help you with the specs.

The first thing you want to check is the pull-off. If the engine is warm when you do this you will need to remove the choke stat and apply pressure to hold the tension in the closed position. Now you bottom the arm in the vacuum diaphram. This is best done with a hand operated vacuum pump attached to the hose fitting. Now you measure between the bottom of the choke plate and the air horn. This is where you need the spec. Depending on what type of diaphram is used you adjust it by either turning a screw on the rod, turning the screw on the end of the vacuum pot or bending the linkage. There are a number of variants of the q-jet and I don't know what you have without seeing it.

The next adjustment you need the manual for the choke plate spec and procedure as well. You place the fast idle screw on the fast idle cam, usually on the second step, but could be some other one. This you need to check in the manual. With it on the second step (?) resting against the ledge to the top step you push the choke plate to the closed position and measure the distance between the lower choke plate and air horn. By measuring these distances in the air horn what you do is use a drill bit of the specified spec and adjust so the distance is the drill bit width between the plate and air horn. You adjust this one by bending the rod that goes from the choke plate vertically down into the carb body.

Steve g

Michael MacPherson

The choke should cose completely when cold and the choke set. after the engine starts the cac diafram should open the choke 1/4 inch. thus allowing the cam to drop to the second setting or lower cold idle setting. Is the choke idle cam loose enough to "free" fall when free as it it supposed to or is it junked up and sticking. And is the Vaccume choke pull off working opening the choke butter fly about 1/4 inch or so, that allows the cam to drop to the second lobe. and as the car warms on up the sspring will open the choke the rest of the way allowing the cam to fall to the neutral or off position. lots of questions. Mike

baja216

I had a similar issue with my '80. I just took some carb cleaner and "worked" the cam a bit to free it up. I've had no issues since.