Cold start Idle speed 86' Ranger Carb

[JamesD]

Cold start Idle speed 86' Ranger Carburetor 2.0 L

No stranger to carburetors, so I will try not to sound stupid here.. On a cold start 40-45 F outside temperature. The engine will start with a pump or two of the accelerator. The is normal because the first pump sets the choke. Once the engine does start the engine is a bit shaky again I know this is normal. My concern is the idle sped seems to be the same on cold and hot start up? From my experience on a cold start the engine should idle up high and then kick down as the engine warms up.

I do have an idle speed motor because my ranger has A/C. The motor is hooked up and the choke is hooked up. I have not check for voltage at ether component.The engine will run on its own after about 20-40 seconds. The idle speed will increase slightly as the engine warms but not by much. This little motor is surprisingly very quite, purrs nicely at idle, and responsive at the tap of the accelerator. Is this normal for or a ranger on am I missing something?

 

[tomw]

I don't have one, mine is EFI, but I thought that the 'motor' was an anti-run-on device that allowed the throttle plate to close fully when the key is moved to OFF. I do not think it bumps the idle when the A/C is selected. If you really want to know, get it warm, and turn on the A/C, observing its motion or lack thereof. I think it just bumps out a 'pin' that pushes on the linkage, and lets it retract w/o power.
That said, does your carb have a stepped cam that is connected to the choke linkage? Most FoMoCo, actually most all, carb equipped vehicles used a stepped cam that falls behind an adjustment screw when the choke plate is closed, and the throttle plate opened. The steps will provide high idle when the choke is closed, and as the choke spring heats, the cam will fall to allow the throttle to close a bit more, reducing idle speed. If the cam is not mobile, due to gum etc, you won't get a fast idle. If the screw has been adjusted improperly, you might not get a fast cold idle.
Post some pics of the linkage...
tom

 

[JamesD]

Thanks Tom. The idle speed motor is defiantly for the A/C. When the a/c is on it stabilizes and increase the idle. The A/C has been long disconnected, although I want to in the future get it going again. I do see the two idle/fast idle screws on the side of the carburetor. I have not studied them yet. Although, I am sure one of them is for the fast idle.

James

 

[RonD]

Tom was referring to the cam on the throttle linkage.

If you look at the choke plate there should be an arm connected to it that runs down the side of the carb to the throttle linkage.
This arm is connected to a cam, when choke plate closes the cam moves and won't allow throttle plate to close all the way, this keeps idle high, as choke opens the arm moves the cam and allows throttle plate to close a little more so idle slowly steps down to warm idle speed.