Road Runner Nest

My 71 GTX was converted to a +6 intake by the previous owner. The fast idle solenoid is not present.

In looking over the engine electrical schematics, it appears that the "carburetor" solenoid (along with the distributor solenoid) is energized whenever ignition is on. Per an article I found on the variations in 6-pack setups, the 71 solenoid has 2 wires instead of 1. The ground wire is connected to the plunger on one end and to a carb mounting bolt on the other. Does this sound correct?

Here's how I assume this functions. WHEN ignition is on, the plunger provides a place for the fast idle cam to catch. As the engine warms and the choke begins to open, the linkage from the choke to the fast idle turns the fast idle cam, and eventually it turns far enough to disengage from the plunger. Operation of the throttle allows that to happen. If ignition is off, the throttles close fully no matter engine temperature or choke position. Does this sound correct?

Lastly, as I understand, the distributor solenoid is to mildly retard timing. What shuts that solenoid off or otherwise disables it to allow normal timing control?

You are describing two separate systems functionally unrelated to each other. First in ’70 and ’71 Chrysler introduced an idle retard solenoid to some vacuum advice units. Two connections, 12v key on, or run position, and a ground lead connected to an insulated carburetor curb idle stop or the tip of an anti-diesel solenoid, if so equipped. When the engine is at full operating temp and at curb idle the speed adjust screw provides a ground to engage/retard the initial timing 5 degrees only at curb idle. Any throttle position off-idle, retard solenoid is disengaged.
The idle anti-diesel solenoid is also energized by the “ign. run” engine harness circuit, providing a curb idle stop when the engine is running and at operating temp, when the key is turned off the throttle plates will close slightly further to prevent run-on.
Again the idle solenoid function is not directly related to the distributor retard solenoid or the choke system fast idle cam.

Thanks. That's making sense. The service manual uses the term "fast idle" and "fast curb idle" which was throwing me off. The pics in my manual are fuzzy which doesn't help. In one of the pics I do see that there is a curb idle speed adjusting screw on the opposite side from the fast idle cam, which I assume is an idle stop. Is that the same screw that contacts the solenoid plunger? I wonder what is setting my idle speed since I don't have the solenoid installed.

If it doesn't rain today I'll back the car out of my overstuffed garage so I can get a look.

I'm not concerned about correctness at the moment, but would like the choke and fast warm-up idle to work. I have an Edelbrock AFB style on my 'cuda with an electric choke which I never did find the right adjustment for, so I converted it to manual choke.

Without an anti-diesel solenoid, curb idle (main or primary idle setting when engine is at full operating temp, choke is off) is set with the throttle stop screw on the throttle body, driver’s side. “Fast idle” generally refers to the fast idle cam associated with the choke system. Adjusted while the engine is warm and the second step of the fast idle cam is manually placed, factory spec. is 1800rpm (page 14-142, ’71 FSM). When running the anti-diesel solenoid system, curb idle is set with another screw at the end of the throttle lever arm. The throttle stop screw is then adjusted to roughly 150-200rpm below curb idle with the solenoid disconnected or above the point where there is throttle blade to bore contact.

Thanks again. Very helpful. After re-reading the FSM, I see they were trying to say what you said, but didn't do that great of a job. I backed the car out and briefly looked at the drivers side - everything seems to be there except the solenoid. Mine is retrofitted with electronic Chrysler ignition. The choke mechanism is there, but I didn't take time to study the fast idle cam.

Mine has an aluminum Edelbrock manifold which looks like the Air Gap variety, but I didn't look for any identification. The normal 2300 choke needs an exhaust crossover to function, does it not?

What is the manifold on your setup? I think I see Edelbrock there.

71_bronze_gtx wrote: The normal 2300 choke needs an exhaust crossover to function, does it not?

Or add an electric choke spring heater system.
Its the Edelbrock 2475, reissue of the ’69 ½ aluminum factory manifold. Air Gap? All big block Mopar intakes are pretty much Air Gaps by design.

Presumably that 2475 manifold has an exhaust crossover, or at least the thermowell for the choke spring is an extension of one of the exhaust ports?

I have an Air Gap on a small block. No exhaust crossover - kind of defeats the purpose of keeping intake air cooler and denser.

Thanks for all the info. I get how this works and how to adjust it now.