WTB 3 port vacuum advance

[Familyguy78]

I need help here. I've vacuum tested the vacuum advance on my 1985 tercel with federal emissions and air conditioning. All 3 ports seem to have broken diaphragms, none of them hold vacuum. Can anyone point me in the right direction? And will a 2 port advance do the same thing, provided I seal off the high altitude compensator? I live in Southern Oregon and doubt I climb high enough to need that. Thanks, all! I hope everyone had a merry Christmas!

[Familyguy78]

Close this one, I found it!

[NWMO]

FG,

I’m sorry nobody chimed in with help. For others going forward, what did you find?, if you don’t mind sharing.

Chris

[dlb]

I need help here. I've vacuum tested the vacuum advance on my 1985 tercel with federal emissions and air conditioning. All 3 ports seem to have broken diaphragms, none of them hold vacuum. Can anyone point me in the right direction? And will a 2 port advance do the same thing, provided I seal off the high altitude compensator? I live in Southern Oregon and doubt I climb high enough to need that. Thanks, all! I hope everyone had a merry Christmas!

sorry, never saw this post. Yes, the upper port with the small hole is for the high altitude compensator so if you only have a two port vac advance, just cap off the HAC.

[Familyguy78]

Chris, I found a functional 3 port vacuum advance on a distributor in much better condition than my distributor. Mine had stuck centrifugal weights and a lot of play in the main shaft, I was able to push the rotor left and right about 4mm. The distributor I found came from a 1986 automatic 4wd tercel, I drive a 1985 sr5 4wd manual transmission tercel. Hopefully this is a drop in replacement.

[dlb]

Yes, it is a direct swap. The # of ports on the vac advance is the only difference between North American al25 distributors. Lucky find, most vac advances are trashed. I think it's usually due to the distributor o-ring leaking oil which seeps into the vac advance unit and slowly breaks down the diaphragms. That's what it looked like on the one I recently dissected anyway.

[NWMO]

Good to hear Familyguy, thank you.

Chris

[Familyguy78]

You're welcome Chris! Now I just need to figure out why timing does not change when I remove and plug the advances vacuum lines...

[dlb]

You're welcome Chris! Now I just need to figure out why timing does not change when I remove and plug the advances vacuum lines...

The upper port with the big hole should advance the timing by 8 degrees at idle. The lower one will have no effect at idle. If the upper big hole one isn't advancing the timing at idle, either the wrong hose is connected to that port, or the diaphragm is not holding vacuum, or maybe the igniter thing (sorry, don't know the actual name for it) that the diaphragm is supposed to move is stuck for some reason. I've never seen the latter occur so I would check the other two first.

[Familyguy78]

It's gotta be vacuum hoses routed wrong... I'll check soon as I can, thank you!