To separate the idle cam from the choke
Wouldn't it be simpler to just run a manual choke? That way you can adjust the choke and idle speed where you need it.
If also installed with a manual throttle.
The way it works right now is I start the engine and it may not be cold enough to set the choke enough to set the idle higher.
I don't want to set it to choke more just to have a higher warm up idle.
Totally sympathetic with that issue.
Here's what I've learned about how an automatic choke is supposed to work. You'll have to investigate whether either of the carbs you've got has all the features.
Initial Choke position: This is where the plate sits when the engine off. Its the maximum restriction to the carb entry.
Qualified Choke position: Plate position immediately upon starting.
* It's opened by manifold vacuum.
* The amount it opens is usually adjusted by increasing or decreasing the spring force on a vacuum diaphram.
* Usually the linkage is such that the qualified position is based on the initial position, not independent.
* It does not effect the throttle fast idle position.
Fast idle cam has two or three steps. In warmer weather the cam's linkage to the choke should rotate it off the upper step(s) pretty quick.
* There may be a way to have the choke 80% open and still have the cam rotated so the throttle is on the second step.
Some carbs have internal vacuum source connection to the choke. They may or may not have a means of adjustment if its internally connected. Some carbs don't have any vacuum source. I think the only solution for them is set the choke for the running position and use pump shot from working the throttle to get it rich enough to fire off.
My own preference is for the choke bimetal to be getting heat from the intake since the intake's temperature is what matters. But that's too complicated for aftermarket carbs so that's not a realistic choice in most cases.
