guys,

i should have a vacuum test guage within the hour and i'm gonna set my air/fuel mixture screws on my carb. it's a holley 750 vac. secondaries.

obviously i'll be tuning for the most manifold vacuum, but what port should i put it on? should i disconnect the vacuum advance and use that? or should i keep the vacuum advance connected and hook it up where the trans vacuum line is? i only ask because when i disconnect the vacuum advance, the rpms will drop. any input? thanks.

Actually, the vacuum advance is plugged into ported vacuum. Or at least it should be. You want to plug into manifold vacuum. The ported vacuum port on Holleys is the one on the passenger side of the carburator 2/3's of the way up the metering block. Leave it hooked up, and use manifold vacuum.

ANY manifold vacuum source will suffice. Manifold vacuum is ANYWHERE below the throttle plates. If you have a fitting in the intake manifold, that will work----------------------it DOES NOT necessarily need to be connected direct to the carb.

Actually, the vacuum advance is plugged into ported vacuum. Or at least it should be. You want to plug into manifold vacuum. The ported vacuum port on Holleys is the one on the passenger side of the carburator 2/3's of the way up the metering block. Leave it hooked up, and use manifold vacuum.

well i'm trying to read up on that. apparently you can make more power if your vacuum advance is hooked up to manifold vacuum, you just need a vacuum canister. i hear edelbrock recommends ported vacuum so they get less tech calls. i don't know. what are the pros and cons of both?

what engine and car is this on? Is this an old holley? If so you may need to have the metering block well plugs and emulsion plugs replaced in order to get a good setting on the air mixture screws. I use the Power brake vacuum port that comes directely off my intake on a holley 396 intake. leave vacuum cannister hooked up. Just set the idle at say 700 rpms, then adjust the air mixture screws so that you get the highest vacuum which will probably increase your rpms. Then go back and re-adjust your idle to where you want it. If it smokes your to rich.