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Old March 23rd, 2015, 02:43 AM
Clarke Clarke is offline
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Join Date: Jan 2013
Location: Eureka Springs, AR
Truck: 1962 1500 Wideside 4 speed (305D / SM-420)
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Default Re: Timing and Tuning

Quote:
Originally Posted by GMCDAC View Post
Hi David, and Scoutmann, I am going to stick my neck out here and guess that the carb you are using is "ported vacuum" which means there is none at idle. "Direct vacuum' usually comes from the intake manifold or the carb base. On the rochesters and holleys I have I just use direct vacuum. Then you will notice the difference when the line is disconnected.

If you have one of those vacuum type brake bleeders the vacuum advance can be tested with that.

DAC
Thanks for the education Doug! I guess I won't worry about disconnecting it in the future. F.Y.I. My new vacuum gauge in installed consistently reads 20 psi at idle.
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