I am trying to run a 72 model Q-jet and a HEI distributor. I can only find four vacuum ports on this carburetor. Two large ones on the back and front for PCV and Trans on back. One on the driver's side mid way up the carburetor that has manifold vacuum and one on the passenger side that sticks way out that is also manifold vacuum. I cannot find one that has no vacuum at idle for my distributor. Is anyone familiar with the pre-75 Q-jets and have an idea what I could be missing here?

 

youd probably be better off using manifold vacuum anyways, smoother idle and better off idle response not to mention more fuel efficient.

 

and no unwanted extra timing on the top end like a ported source would give you

 

Thanks for suggestion Pablo. That port on the driver's side turned out to be ported. I just had the idle turned so high to intitally get the motor started the blades where opened enough to give it full vacuum almost. In any case I am experimenting between full vacuum, ported, and non at all. To be honest the ported has felt the best driving around so far. I am going to wait till I get the motor good and broke in before I do any serious tuning though. Thanks.

 

Have you ever put a vacuum gage on those two ports to see what you get at WOT?

 

Ported goes to zero at WOT last time I checked...