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Old 06-15-2009, 07:11 PM
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Quote:
Originally Posted by ERA Chas View Post
And what do you do when your idle vacuum is 7" with a 250+ cam?

Well, if you have a MSD dizzy, you can use a GM vacuum advance unit (that's all MSD uses) part.# vc 1807, 1808, 1809 or 1812 depending on how you want to fine tune your timing curve. All of them start at 5" of vacuum and are all in by 7".
Vacuum advance is one of the most mis-understood parts of an engine and my guess is that 99% of those out there have no idea how to properly tune an engine for the best performance.

Jim

Last edited by jwd; 06-15-2009 at 08:32 PM..
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