Dual Port Distributor Vac Advance

[7991LXnSHO]

Just a quick question. This is a 1968 Mustang with a (not stock?) 302, and I think the dual port vac advance canister looks like it is hooked up wrong. Which line goes where? I think one is a timing retard and the other is an advance?

 

[horseballz]

Hey,
If you PM me your email, I'll do my best to find the complete vacuum schematic and email it to you. If I recall, you are correct that one of the nipples is retard and it needs to go to a ported vacuum switch in the thermostat housing. General consensus has always been that it didn't really work very well and that the retard portion could successfully be ignored, unless of course you are doing concourse shows, etc.
Let Me Know,
Gene

 

[rbohm]

you can run the vacuum line to the outer nipple. that one runs the vacuum advance. the inner nipple is for the vacuum retard, you can leave that open unless you need to retard the timing at high rpms, or if you are running boost and want to pull back some timing.

 

[7991LXnSHO]

Considering the $$ that it cost to do the body, and the motor was supposed to be done before I got it, I also want it right under the hood.

I was just reading about how the IAT affects on the 5.0 programming. It pulls back timing a bit at high temps to prevent pinging. Is that what this ported vac switch controls? Does anyone know at what temp it opens (or closes if I have it backwards)?

 

[rbohm]

Considering the $$ that it cost to do the body, and the motor was supposed to be done before I got it, I also want it right under the hood.

I was just reading about how the IAT affects on the 5.0 programming. It pulls back timing a bit at high temps to prevent pinging. Is that what this ported vac switch controls? Does anyone know at what temp it opens (or closes if I have it backwards)?

it was done for emissions. when the engine got hot the vacuum port would open up and pull back the timing.