I'm having a problem with a carb I bought used and rebuilt. (Yes, I used a Holley rebuild kit.) It's a Holley 4160 (750 CFM, vacuum secondary), List #3310-2, with #2726 stamped below the list number on the air horn. The problem I'm having is that the vacuum port on the side of the primary metering block, which is normally supposed to be "ported" vacuum for the distributor's vacuum advance, is in fact manifold vacuum. I checked with my vacuum gauge - it reads about 18" of vacuum at idle and drops when you goose the throttle, which is the opposite of what you want for the distributor vac. advance. Other than this, the carb seems fine. Interestingly, this is the ONLY vacuum port on the entire carb, there are NONE on the throttle plate (which would be manifold vacuum anyway). I took it apart again and followed the passage from the port, through the metering block, and it goes right to a hole in the body that comes out on the bottom of the carb, below the throttle plates. Do you think the carb has the wrong metering block, or the wrong gasket, or is this normal for this carb? If this is the case, I guess I'm screwed for vac. advance. I'd like to be able to have ported vacuum for my distrubutor (which I realize is a whole 'nother discussion, based on my newsgroup reading!) If it helps, the numbers on the metering block are: L33102 5271 5275.
Thanks for your help, Dave '72 RS Z28