dual vacuum distributors



For the '68-73 dual advance distributors with dual vacuum advance, where did the vacuum hoses connect to? Was it advance side to carb. and retard side to manifold?

Did these cars use any ported vacuum switches installed in the coolant system (i.e. thermostat housing) to control the retard (I think). I saw a ported vacuum switch on AzCoupe's thermostat housing.
Good question. :LOL:

I had the same question for SEVERAL months. I have the dual vacuum setup as well. I have been told to get the single vacuum distributor for my car but after already paying 50 bucks for the new distributor I decided just to us what I have rather than return it to the parts store (I was REALLY lazy and fustrated).

I ended up running the advance side (most outer nipple on the diaphragm) to the carb. and the retard to the manifold.

I also eliminated the ported vacuum switch. This made a big difference in performance.

Another thing you can try (I did this as well) would be to eliminate the tree and plug the retard on the distributor as well as plug the manifold. So the only vacuum line you would have plumbed would be the advance from the dizzy to the carb. This also made a big difference for me.

Just some thoughts.

yeah, I am still confused. My PCV thingy off the water neck has 3 nipples.
1) to carb/ manifold nipple (it has a T)
2) to outter nipple
3) Plugged.

I dunno.....
Okay here we goooooo hold on I'm going to TRY and explain some this....

chazthephoenix that PCV thingy you are referring to is called a ported vacuum switch. It was incorporated in ALL late model Fords to help in reducing emissions along with a few other thinks (i.e. dual vacuum distributors this was needed to work with the PVS).

Now all of this was done BEFORE federal regulations on emissions went into effect. Later, Ford as well as others, introduced electronic ignition controls and other things that eventually replaced alot of the vacuum plumbing that was required at the time to reduce the emissions (IIRC).

I need to stop here to say something about pollution. :unsure:

It's not good, PERIOD.

However, if you want a good performing machine the simpliest thing to do would be to eliminate the PVS and plug the thermostat housing. Also plug the retard nipple on your distributor as well. This would then leave ONLY the advance line running from the dizzy to the carb. With this setup, tuning is do much easier!

IF (big if) you feel you need to run all of those vacuum lines, then by all means get a Mustang repair manual that shows a diagram for your year and plumb it accordingly. One word of caution...Fine tuning your car will be DIFFICULT if you take this approach! I speak from experience.

Hope this helps guys.