Fast idle cam problem...

[Darrman]

I had my Autolite 2brl pro rebuilt a couple months ago, when I got it it would catch the fast idle cam like its supposed to, push the peddle down that kind of thing. Now that I am finally driving the truck, the cam doesnt move on its own anymore.
Whether by peddle or by hand, the cam wont move on its own, however you can easily move it manually into place, after that it will idle the motor at 1200 till you hit the peddle, just like its supposed to. This means I have to pop the hood to start the truck cold, unless I hold the gas down myself.
How do I fix this, I cant tell how to adjust it, and I dont want to screw it up.
Thanks!

[lee_ford]

Loosen the screws that hold the large round black choke spring “can” (as in container) on the opposite side of the carb a little to allow it to be turned. There is a fine adjustment to get it is just right. So if possible do it with the motor cold. On a warm day set it so the spring is just moving the fast idle cam into place. After you start the motor and let it run a minute or two the choke spring warms up and unwinds (or winds up tighter, I forget which.) and the choke is opened and the fast idle cam is pulled out of the way.

Red arrows point to screws and Blue arrow to Spring holder/can.

Autolite.jpg

[wilhay]

Hey lee_ford, the pic you posted to answer Darrmans question, on the other side of the carb that thing attached to the throttle linkage which i assume a some kind of solenoid,what is it and what does it do. I'm fixing to rebuild my carb,do i need to replace it, i've tried to find one but nobody has it and it doen't help that i don't know what it's called. Also on the back of my carb there is another solenoid looking device that has a vacuum line coming out of it and going back in to another part of the carb, what is it and what is it for. 1972 bump with 302 manual tranny non electric choke.
Wilhay

[wilhay]

Hey lee_ford, the pic you posted to answer Darrmans question, on the other side of the carb that thing attached to the throttle linkage which i assume a some kind of solenoid,what is it and what does it do. I'm fixing to rebuild my carb,do i need to replace it, i've tried to find one but nobody has it and it doen't help that i don't know what it's called. Also on the back of my carb there is another solenoid looking device that has a vacuum line coming out of it and going back in to another part of the carb, what is it and what is it for. 1972 bump with 302 manual tranny non electric choke.
Wilhay

[lee_ford]

…on the other side of the carb that thing attached to the throttle linkage which i assume a some kind of solenoid,what is it and what does it do…

I do not know what it is called, but it is needed if you have an automatic. It is a counter spring for the throttle return spring. What it does is press on the throttle just slightly. When you put it in gear, the RPMs drop and the vacuum drops letting this piece open the throttle just a tad, thus raising the idle and keeping the motor from stalling. It also works when you come to a stop. Basically, when the truck is in gear and not moving, the motor needs more throttle than it does in neutral to keep running.

Also on the back of my carb there is another solenoid looking device that has a vacuum line coming out of it and going back in to another part of the carb, what is it and what is it for….

I would have to do a little research to picture what you are referring to. Maybe someone else knows.

[bigfootbryce]

Also on the back of my carb there is another solenoid looking device that has a vacuum line coming out of it and going back in to another part of the carb, what is it and what is it for. 1972 bump with 302 manual tranny non electric choke.

Wilhay[/quote]

that's called the choke pull off. on a cold engine the choke valve should be completely shut. when you turn the engine over, it is activated by vacuum. it opens the choke valve a smidgen, so the engine can breath.

[knightfire83]

The electrical device is called an idle stop solenoid. The auto maker used it for a few different functions.

Some used it as a cure to stop dieseling after the ignition would be shut off. They solenoid would have power when the engine was running and hold the throttle plate open for an idle. When the key was shut off the throttle plate would be 100% shut and the engine had no fuel to run on and on and on (dieseling.) Mostly GM applications.

Others would use it to kick up idle when the A/C was turned on. When the compressor is running it used more power from the engine dragging the idle down. So they used this solenoid to raise the idle when A/C was turned on.

Or even to raise engine speed when using PTO accessories or welders and such.

I've ran a switch to them before to kick up the idle when the engine was cold in winter. Switch on higher idle, switch off normal idle. Very useful.

On newer engines this function was replaced with the IAC (Idle Air Control Valve.)

Can't say I've seen them used on our trucks unless it was equipped with A/C.