Timing Dance ! Vacume Advance ?

FWIW, the Mopar Performance distributor has a fully adjustable mechanical advance so you get more for your bucks than just a stock distributor with light springs. Also, the MP distributor does not have the phasing issues that the stock distributor has and the action of the vacuum advance is smoother and more consistent. Don't be fooled by the stock looking housing, internally it's the same as a Mallory performance distributor. If you are running a bigger cam and/or more compression than stock it is very likely that you will need to run a lot more initial timing than stock which will require you to limit the advance so you don't have too much on the top end, this distributor makes that a snap with the adjustable stops and also has a much wider selection of springs available to dial in the rate.

At light throttle low load cruising you need a lot more timing than the mechanical advance can give you. Yes you will get more timing at a lower rpm with light springs but for maximum efficiency and economy when cruising you need 40 or more degrees of timing.

My son had given me a MP billet distributor for fathers day which I put into my 360 when I built it. I never felt right about not having a vacuum advance so after a couple of years I switched back to the MP vacuum advance distributor. I gave up zero in power or driveability and picked up 1.5-2 mpg on my daily commute not to mention the cleaner running engine and less carbon build up.

I can't imagine why anyone that is using there car regularly on the street wouldn't want a vacuum advance.