vac or no vac?

i am ready to get a distributer for my :v6: and will be getting a DUI.
my question is about which option to get,i can get it with or without vac advance.i will be geting it from http://www.performancedistributors.com/
my question is which would be better for a jeep that will get equal off and on road action.
the engine is slightly built with headers, cam, intake.
thanks in advance guys.R)

 

i removed the vacuum can from my hei odd fire dist so it would be easier to fit. it was too tight a fit with the fan and couldn't get it to time right no matter where i put the #1 pole except when the vacuum hit the fan or the thermostat housing. i may find a smaller can someday but right now it's not a priority for me.

i really can't say that i have noticed any drop in mpg in town or not.

runs just fine. just make sure you plug the vacuum line if you don't use it.

 

go with the vacuum advance model.

 

I run a dual pointed Mallory on my 225, the model I have didn't come with a vacuum unit and theres no place to put it. It runs fine.

 

so it seems i dont need it. alright thanks again guys for helping me solve another one of my jeep questions.R)

 

I don't run vacuum advance on my hei but I might some day. The old hei dist that I got had a bad vacuum unit (canister?).

I did look in the book at NAPA and discovered that there are many many different configurations, where the hose connects in a different spot - it's good to know you can get something different if you have a clearance issue. Also, there are many different pressure (spring) ratings for differing amounts of advance vs vacuum. Using this method to tune up your vac advance may or may not be better than the aftermarket adjustable units.

Note - if you take the parts off of your distributer so you can take it into the store, don't drive around with it disconnected. Your motor will make bad sounds as the timing moves around to some radical amount of advance. DAMHIK.

 

somewhere on this site is a method i posted to lock down the advance if you remove your vac. it can be undone if you want to add the can back on.