adding ported vacuum

[pishta]

drilling a carb for a charcoal can ported vacuum source. Does the size of the port matter? The one I need is like the size of a ball in a ball point pen but I dont have a drill that small thats 4" long. I thought vacuum was vacuum, cant regulate it? maybe put a small carb jet in the hose? Thanks.

 

[67Dart273]

I don't think I've seen a carb in the last 40 years that did NOT have ported vacuum??

But ported vacuum IS fancier than just drilling holes. Years ago, when I was swapping back and forth from TQ, QJ, and Holley SB, I found that all three had different ported vac. characteristics, so far as vacuum advance goes. Back then I still had the 340 in the RR, so, hi comp. engine, lots of weight, temp, and possibility for part throttle "ping."

 

[pishta]

This is that crazy carb for the MAzda. the NOS one was missing the 3rd charcoal fitting. drilled fine but the hole in the venturi turned out a little bigger than planned...