Help!! Is there any way to run vacuum advance on sbc w/ edelbrock triple manifold and progressive 3x2 97's?? I currently have the vac port @ the distributor plugged for initial timing. I would like the cool idling and better throttle response of vac adv. Appreciate any advise
I'd get a set of 1/2" carb spacers with the fittings on the side so you could hook up the vacuum advance.... Unless you want to drill and tap the intake for a fitting...
If you don't want to drill your intake or have an existing threaded hole into the intake, simply use a thin plate desiigned just for the purpose of adding vacuum under the middle carbie. There are all types and they are easy to install, being thin enough so you won't even have to use longer mounting studs. Check my threads as I think there is a picture of one I had for sale a whileback. I'd give you the link but I don't have a clue how to do it.
Thanks for the help. If I did tapped into the manifold or added a spacer that would me manifold vacuum only. I was always taught to add the vacuum advance above the throttle plates unless under race conditions. I don't want to tap into the carb. Just curious if anyone else has had this issue and if they Just left it plugged how did it run. Dont have the brakes plumbed yet so a test drive might get a bit crazy. Thanks!!
You might be able to reposition your wires in the cap to get a better position for the vacuum advance....
http://www.ecklerscorvette.com/corvette-vacuum-advance-carburetor-stud-hollow-300hp-1962.html try something like this...
You were taught wrong, vacuum advance needs to be drawn from under the throttle plates, manifold vacuum.
Look around swap meets for a thin 3 bolt carb spacer with a vacuum port on it. I believe they were used on cars with a columbia 2 speed rear axle, or so Im told. I was also taught wrong about distributor vacuum ports. I believe it was Tommy here on the HAMB who posted a GM engineering essay on the principals of vacuum advance which convinced me I had been wrong all along!
Manifold vacuum is correct but just check the port for vacuum at idle. Rochester carbs pick up the vacuum advance high on the body of the carb but internally it does come out below the throttle plates giving manifold vacuum even though the vacuum port location is well above the throttle plates. I run the vacuum advance to the port for the vacuum wipers on the intake. The advance just pulls on a diaphragm so there is no air flow to lean out the mixture.
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