I did a small test. I sucked on the hose going to the distributor and pinched it so it was in full vacuum.

Then I took her for a test drive. I could not feel any difference in performance. Now I'm really confused and feel like I'm in the 'advanced' stages of 'retardness'.

I think the only way to answer the retard/advance question is to put timing gun to work. Unfortunatly I don't have one. Next week I'll be visiting someone that does, so I'll remove the hose and suck on it at idle and see if the timing advances or retards.

Tony

If your Dist. vacuum mechanism has only one inlet for a vacuum hose than it is safe to assume that it is a retard type unit. The rotor should rotate slightly clockwise if the vacuum unit is operative to retard the timing. Try checking it with a vacuum pump. It should hold without leaking down.

I had 78 SC that came with a single diaphram vacuum advance only which had absolutely no influence on the way the engine idled.

But, what did make the engine hunt at idle was setting the mixture a bit too rich like most P-wrenches like to do.

Cheers,

Joe