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  • 1965 - 1973 Classic Mustangs -General/Talk-
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Dual Port Distributor Vac Advance

  • Thread starter Thread starter 7991LXnSHO
  • Start date Start date Jun 14, 2015

7991LXnSHO

wanna catch the space herp
10 Year Member
Sep 1, 2010
7,387
2,745
194
Kearney, NE
Jun 14, 2015
#1
  • Jun 14, 2015
  • #1
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

10 Year Member
Sep 30, 2009
824
19
49
Las Vegas, NV
Jun 15, 2015
#2
  • Jun 15, 2015
  • #2
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

Founding Member
Apr 12, 2002
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204
tucson,az
Jun 16, 2015
#3
  • Jun 16, 2015
  • #3
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

wanna catch the space herp
10 Year Member
Sep 1, 2010
7,387
2,745
194
Kearney, NE
Jun 16, 2015
#4
  • Jun 16, 2015
  • #4
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

Founding Member
Apr 12, 2002
6,698
550
204
tucson,az
Jun 16, 2015
#5
  • Jun 16, 2015
  • #5
7991LXnSHO said:
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)?
Click to expand...

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