Idle speed: trying to get it just below 1k

[94Griff500]

Searched alot and still have questions.
-94 Griff 500 pre-serp with full engine rebuild.
-New dist vac unit.
-Idle stepper wiring disconnected
-Throttle cable is loose / not interfering with linkage
-Running 10 degree initial advance with the vac line disconnected & plugged.
-Can't get idle below 1k with the stepper hose clamped shut and the air idle control screw fully seated/closed.
-I've sprayed ( carb cleaner ) all over the intake manifold and fittings to try to find any potential air leaks, but no idle change so assuming no air intake leaks.

Supposedly, if I clamp shut the stepper hose, and completely screw in / close the air idle control screw in the manifold, I should be able to get the idle down to 600 rpm to the point where the engine stalls, but that doesn't work ! Best I can get is 1,000 rpm....

Suggestions? Ideas?

Doug

[Sardonicus]

Check no one as fked about with the plenum butterfly stop screw if you can see a gap between the butterfly disc and the plenum body then I would suspect they have previously , best checked with the plenum removed from engine and upside down (leave cable attached) of course do this after checking all other avenues (sounds like you have that one covered0 check fuel pressure reg pipe is in place too

[94Griff500]

Will do! Thanks for quickly posting!
I can see where the throttle linkage arm is just literally hitting the edge of the bracketry closest to the firewall & preventing the throttle shaft from rotating any more...I can hear it "clink" when I pull the throttle linkage open slightly & let it go, so that appears to be a "mechanical" stop for the throttle shaft linkage. Should that be happening?
Question: Are you talking about "adjusting" the plastic dual screw 3 wire part that attaches to the throttle shaft on the FRONT edge of the manifold?
That appears to have been adjusted within the "slots" in the plastic, but I didn't want to start moving everything without first getting some feedback.
If that's the part your referencing, is there a specific way to properly set it, or is it a "loosen & try adjusting it" approach to drop the idle speed?

Doug

[Belle427]

The 3 wire component your referring to is the throttle potentiometer.
The throttle stop screw is under the mechanism when the throttle is closed if that makes sense, shown circled here but its not normally messed around with.
Id still say you probably have a vacuum leak somewhere.

[Sardonicus]

Belle427 said:

The 3 wire component your referring to is the throttle potentiometer.
The throttle stop screw is under the mechanism when the throttle is closed if that makes sense, shown circled here but its not normally messed around with.
Id still say you probably have a vacuum leak somewhere.

True but I've seen them where the arm (in your pic) that touches the stop grub screw as been bent trying to fix other idle issues hence why I mentioned the air gap around the throttle blade

[blaze_away]

It's probably simply a vacuum leak. Get a smoke tester on it it will show you exactly where it is.