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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269

Agreed. I hope we get to the bottom if this.

I hear what you say about how you think these things work.

My thinking is the Vac line is ported and comes in just outside the throttle plate so it dose not see any vacuum at idle but only above idle.

If timing is near 0 or TDC at idle, the mechanical advance would take one to about -16 to 20 deg with acceleration. Then at cruse when the manifold sees vacuum, timing is then advanced about another 9 degrees for a tottal of 25 to 29 deg at cruse.

With acceleration, the Vac advance goes away and we drop back to -16 to -20.
Old 03-30-2010, 08:43 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #32 (permalink)