TedH

Almost 15 years ago, I had my advance dialed in to get 15, 25 and total 36 degrees (all-in) at idle, 1500 and 2500rpm respectively.

With my most recent engine refresh, I am getting much more timing at idle; close to 25 degrees. Could this be due to tired/weak advance springs? I am having to turn the distributor clockwise to reduce idle sufficiently (retarding the timing). The screw on the throttle is backed out all the way so I cannot lower the idle that way. I am getting some 'run-on' when I shut the engine off with the dizzy retarded.

Once I have the new v-belts on Thursday morning, I plan to put the timing light on it and re-measure the timing at idle, 1500 and 2500 rpm's.

SH-60B

That is too much advance at idle with the vacuum disconnected. If it's connected, unplug it and reset the timing. Run on can also be too fast idle or even too low octane fuel. Did you "refresh" the carb? Make sure the throttle blades close all the way at idle.

TedH

Remembering one of Lars' instructions, I switched the vacuum advance source on the Q-Jet from the top (ported?) to the lower (manifold - port just above the baseplate) outlet. The idle dropped and I was able to advance the distributor again (turning it counter-clockwise) back to the sweet spot of timing. I had incorrectly connected the hose when I re-installed after having Lars refresh the carb.

I confirmed this instruction from the internet (several sources): "...use manifold vacuum for the advance on non-emissions controlled vehicles and the timing(ported) vacuum for emissions controlled."

This makes sense as I no longer have manifold and air cleaner sensors that control the vacuum signal to the distributor. This is definitely a PERFORMANCE engine as Duntov intended

jim2527

Rubber band the weights so they don't move then recheck. If timing is reduced that means your weights are advancing at idle. I read somewhere you want mechanical to come in a little above idle....not sure how much of that's true.