Article by Hemmings on Vacuum Advance - ported or manifold

[Don C]

This subject has been discussed in the past on this forum. I thought that this article is worth bringing it up again.
https://www.hemmings.com/stories/ignition-tech-where-to-hook-up-your-vacuum-advance-distributor/

 

[Hemikiller]

A quick skim and I find his position refreshing, in that the true answer is "it depends on your application".

One thing to remember in the ported vs manifold debate, is that an engine with an emissions tuned distributor (like those factory in our cars) will *usually* have a huge amount of advance on the vacuum side. IE: the 71 351C-2V distributor for manual transmissions has 24° of VA built in, the 302-2V stick unit has 22°. You'll have a hard time getting a reasonable idle speed without modifications.