Distributor and carb. question...

[Nealio240z]

I have a pertronix HEI unit with mechanical advance and vacuum advance. I also have a Q-jet carb... My question is; where on the Q-jet carb Should I put my vacuum advance "suction" line? Does it go on the top passenger side or the bottom driver side? I dont know which is full vauuum port and which is not... What does the distributor require for a vacuum port? Please help school the retarded -(me)

[icewtr]

You want the distibutor line hooked to the one that has no vacuum once you open the throttle wide open .. it should have good vacuum at idle and with a guage hooked on it hit the throttle and see if the vacuum guage goes to zero if so then hook it to that one ..

[Nealio240z]

Whats what on a Q-jet carb???

[jt1]

Nealio, it's not that simple. There are at least several different models q-jet, and the timed/manifold nipples are in different places.

 

 

You can use either one, it just affects the way you set up the initial advance and the mechanical advance. The intent of the vac advance is to advance timing under light load part throttle conditions (cruising) to maximize gas mileage. I have had better results use a timed port, ie one that provides no or very little vac at idle, then provides vac as the throttle is opened. It makes things simpler and that is good for me.

 

My advice is to read up on what the vac advance does, how it does it, and determine which nipples on your carb give vac at different times. Then when you set it up your car will run better and you will have a good have a good understanding what's happening. Unfortunately I'm not familiar enough with the different models of the q-jet to give much help there.

 

John