Engine 258 Tuning troubles

[HappyJohnny]

Started up my rebuilt AMC 258 i6 / 4.2l (1978 CJ5 ) and can't get it below 1500 rpm @3 deg timing. Idle stop screw is all the way out, vacuum disconnected.

If I set the rpm to 850, the timing is 10+ deg, and I can't give it any gas without stalling. At that idle, it also continues to run for a bit after turning off the key! Idle mix is 1.5 turns out.

 

[Jeep Soup]

Did you Rebuild the Carburetor too?
It sounds like a Cocked Throttle Plate, or Other issue binding the Throttle Cross Shaft partially open.
Is there not enough slack in the Throttle Pedal Links holding it open?
Run On after you turn off the ignition is usually a Dieseling Effect.

 

[HappyJohnny]

Did you Rebuild the Carburetor too?
It sounds like a Cocked Throttle Plate, or Other issue binding the Throttle Cross Shaft partially open.
Is there not enough slack in the Throttle Pedal Links holding it open?
Run On after you turn off the ignition is usually a Dieseling Effect.

Yes - the carb was rebuilt, but I'll go through it again to confirm that the throttle plate and linkages are correct. Thanks!

 

[boney]

Sometimes it's the simple things.

When you say "vacuum disconnected" do you mean removed from the distributor and plugged? I usually just clamp it with needle-nose vice-grips that have a piece of hose around each of the jaws (so they don't damage the vacuum hose).

 

[HappyJohnny]

Sometimes it's the simple things.

When you say "vacuum disconnected" do you mean removed from the distributor and plugged? I usually just clamp it with needle-nose vice-grips that have a piece of hose around each of the jaws (so they don't damage the vacuum hose).

Correct - I cut off the vacuum by clamping the hose! Will fuss with it again tomorrow!