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Old 01-07-2008, 08:54 PM   #10
VetteVet
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Join Date: Jan 2005
Location: Kalamazoo, Michigan
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Re: Where does my distributor vacuum go?

Quote:
Originally Posted by hdflstf View Post
None of the above is entirely correct.

What you need is to hook up to the vacuum post that DOES NOT (assuming everything is set up properly) have vacuum at idle. Once the throttle is opened slightly, the port will have vacuum. From there, the vacuum will be engine vacuum which changes depending on throttle position and engine load. The port you are pointing to looks to be the right place. You do not want straight manifold vacuum as you will have a hard time setting and keeping a consistent idle speed.
What you have posted is correct except that the OP did not indicate whether he has an HEI distributor or the stock points system. The vacuum advance is designed for full manifold vacuum at idle. The diaphragms are different between the two and the normal hookup for the points distributor is at a tee on the rear of the manifold behind the carb. IT shares a connection with the brake booster and the trans vacuum modulator.

It appears from the picture that he does have an HEI distributor, if so then my post is for informational purposes only.
There are tuners that recommend using full manifold vacuum in all cases and claim better performance. I can not substantiate that so I will defer to the experts.
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