Dizzy vac advance (1 Viewer)

[BlackDiamond72]

Sorry if this has been addressed before but I am having a hard time finding anything.

The dizzy on my '78 fj 40 has two ports for vacuum lines. One points vertically and the other horizontally. I have been told the line from the carb port for vac advance goes to the horizontal port on the dizzy. Is this correct?

Also, what about the vertical port on the dizzy? Is this vac retard for when the engine is under heavy load. Should I plug this port? On a desmogged rig, is there a way to run a vac retard without drilling a port in the carb secondary?

Thanks all you advance/retard gurus!

 

[Pin_Head]

You don't have to be a guru: You could just pop the cap off the distributor, pull a vacuum on the two ports and take a peek at which way the plate rotates.

But since you asked, the port farthest away from the cap is advance and it is typically horizontal when the rubber side is down.

 

[FJ40Jim]

Also, what about the vertical port on the dizzy? Is this vac retard for when the engine is under heavy load.

No, vac advance is for when the engine is under heavy load. Vac goes away under load, retarding the timing as necessary.

Vac retard should just be left open to atmosphere.