Suddenly Won’t Idle below 1800 rpm???

[PurpleBeeper]

440 6bbl w/steady fuel pressure, electronic Direct Connection distributor. Some of this might be unrelated. Car was running well with a good amount of initial timing. New heads & valves adjusted less than 1000 miles ago. Engine would “cough” out of the carbs “occasionally” during startup. Power valve protection check ball added to center carb. 6.5 power valve.
1. Moved my white accelerator cam from position #1 to position #2
2. Accidentally made a + & - wired short (idle solenoid or N2O system) which melted some wires, but car still ran fine (surprisingly). Repaired all the melted wires.
3. Replaced ignition pickup & gapped to 0.008” with brass shim guage. Old Mopar NOS part.
4. Replaces Summit/Jegs (?) brass insert distributor cap & rotor with new Autozone Cap/rotor (rotor not brass)

Now, the car won’t idle below 2000 rpm. I replaced the pickup without removing the distributor, so timing never changed.

Any ideas why it won’t idle anymore?
THANKS!!!

 

[70 sublime]

Vacuum leak ?

 

[Don Frelier]

So you made 4 changes at once?

You might try putting the old cap and rotor back on and you can rule that out.
Pretty easy to do.

 

[493 Mike]

Has the idle solenoid stuck open too far?
Mike

 

[MWbirdLOVER70]

Has the idle solenoid stuck open too far?
Mike

Butterflies catching on vase gasket and holding open?

 

[dvw]

When you replaced the pick-up did the vacuum canister arm get jammed under the plate? hat could have change the timing.
Doug

 

[PurpleBeeper]

Vacuum leak ?

Good point. I did burn up the vacuum hose going to the the front carb. I replaced the hose, but maybe I missed a hole on another section.

 

[PurpleBeeper]

So you made 4 changes at once?

You might try putting the old cap and rotor back on and you can rule that out.
Pretty easy to do.

That's a good idea. I just replaced what was burned up & added the cap/rotor because the rotor was slightly discolored on one edge.

 

[PurpleBeeper]

Has the idle solenoid stuck open too far?
Mike

Good idea, but I can see it's not touching.

 

[PurpleBeeper]

Butterflies catching on vase gasket and holding open?

Makes sense, but I never removed any of the carburetors, just the cam & guts of the distributor all on the motor.

 

[PurpleBeeper]

When you replaced the pick-up did the vacuum canister arm get jammed under the plate? hat could have change the timing.
Doug

That makes a ton of sense. I will take a look while I'm putting the old rotor/cap back on.

 

[Don Frelier]

That makes a ton of sense. I will take a look while I'm putting the old rotor/cap back on.

Put a timing light on it. Another easy check

 

[Geoff 2]

You do not mention what the correct idle rpm was. I will assume 1000 rpm. If it is a dist problem, a problem with the timing is not going to increase idle rpm an extra 1000 rpm.
This is a H problem or base gasket problem. Something happened when you were messing with the carbs.

 

[PurpleBeeper]

You do not mention what the correct idle rpm was. I will assume 1000 rpm. If it is a dist problem, a problem with the timing is not going to increase idle rpm an extra 1000 rpm.
This is a H problem or base gasket problem. Something happened when you were messing with the carbs.

Idle was about 900 rpm. The carburetors were not removed, so I can rule out the base plate gasket (accelerator cam changed without removing any carburetors). What is “H”?

 

[BSB67]

To have an idle that high, air is getting into the motor, most likely.

If so, it’s not a small leak. More like the PCV valve hose is off, or a carb throttle plate is stuck open.

 

[Rebelrouser]

I would lean to throttle plates sticking, maybe a diaphragm bad on the outer carbs. One trick is to blow carb cleaner, and compressed air through the air bleeds, sometimes a backfire can lodge carbon in the bleeds.

 

[Don Frelier]

To be clear:
Idle speed won't drop
OR
Does it quit if you run it below 2,000?

 

[PurpleBeeper]

Good question! The car idled smoothly at 900 rpm. I had an electrical fire that burned up the leads going to the distributor pickup. The pickup wires didn’t short out, actual flames burnt the insulation off (car still idled & ran fine after the fire).

After I fixed the wires and replaced the pickup with a NOS Mopar pickup, the car ran ok, but the idle at 900rpm was “very slightly rough”. I didn’t have a feeler guage at the time & my pickup to reluctor gap was “eyeballed” and probably at about .015” (?). I also noted the rotor that was in there was “slightly” discolored on one corner.

I worked on the car again & set the pickup/reluctor gap at .008” with a brass shim. At the same time, I replaced the cap & rotor and inspected the plug wires for fire damage.

After that, the car wouldn’t stay running at 900 rpm, even after it was warmed up to 185F. I had to turn the idle up to 1800 rpm just to keep it from stalling

 

[BSB67]

Boy, don’t a couple key facts clear things up.

 

[PurpleBeeper]

To be clear:
Idle speed won't drop
OR
Does it quit if you run it below 2,000?

To be clear:
Idle speed won't drop
OR
Does it quit if you run it below 2,000?

Good question - see post