Vacuum advance information and myths

Bewy said

RB,
Post #52. More BS. The dyno tells you how much timing the engine wants, not a dist machine.

And yes, more timing at idle with longer duration cams. Timing at idle with Chry engines is the initial timing, usually in the 8-12* range. A 220 @ 050 cam is not going to need 50* at idle & I never said such a cam would need that much. It might need 20-30* & testing will show what it does need. Man vac adv would be one method of adding the extra timing.

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Yep. And the dyno isn’t the last word on a timing curve either.

BUT, you don’t need a dyno to set initial timing. What you do need is a distributor machine to change the shape of the curve and to make sure (for anything with what you think is long cam timing) you don‘t start the curve too soon.

Or you can guess.

I do the former. I have no clue what you do except stick a vacuum hose to manifold vacuum and call it good.

I‘ll say it one more time. If you NEED to add timing at idle with VA and MV you need to rethink your compression ratio, your cam timing or both.

There is far more power and drivability in those two things than you’ll get by crutching a bad combo like that.