Vacuum Solenoid Switch - Spark CTO

[cjTango]

Fellow Jeepers:

I need some help finding a part. I’ve had no luck with the typical auto parts stores, nor my own internet searches.

I’m trying to find a replacement for my vacuum solenoid control switch. That is the generic term for it. Specifically, this switch controls vacuum from the spark CTO. It opens (power is removed) when the tranny is in 4th (high) gear. Otherwise, power is applied to the switch and the switch is closed.

The number on the part is 3218737. The only other text is “Dole Carol Stream 60187 ILL” which - as far as I can tell - is a place.

I attached some photos so you can see what I’m looking at.

Thanks in advance for any help.

 

[Lumpy Grits]

:ww:

Have you tried to cross-reference the PN to other vehicle makes?
Try here-
https://www.willysworks.com/

Best to call them.
Let me guess, you need this to pass PRKs, SMOG test.
LG

 

[hagar]

Transmission controlled spark switch.
Used on AMCs from 1974 till forever.
6 cylinder and V8 models
Boneyard ?

 

[cjTango]

:ww:

Have you tried to cross-reference the PN to other vehicle makes?
Try here-
https://www.willysworks.com/

Best to call them.
Let me guess, you need this to pass PRKs, SMOG test.
LG

That website looks pretty legit. Definitely bookmarking that one. Thank you.

And, fortunately for me (even more so for this CJ), in California 1975 and older are SMOG exempt. This part is suspect, though I don't think it has anything to do with another more urgent problem I'm working. Read on...

I'm actually just trying to get this thing running smoothly. I rerouted the entire vacuum system last weekend putting on new manifold & exhaust gaskets. I had to reroute because I was comparing the lines in the service manual and noted they were not run that way when I pulled the manifold off. Now, the engine starts and idles perfectly. I mean, it sounds better than it has in the last 2 years of (Limited ) use.

BUT... now when you give it gas (not moving) and the engine gets to the ~2200-3000 RPM range, it sputters and looses RPMs. If you give it more gas, it "pushes" through this range and sounds fantastic again above ~3000 RPM.

I'm going to check the EGR CTO (2-port) and spark CTO (3-port) vacuum ports on the engine block to make sure they're working properly. I've never had to mess with a vacuum system to this extent and it's...going.

If you know what's going on in that mid-range, I'd like to hear it. Seems like something may be getting starved of fuel/oxygen. Maybe it's in the carb or ignition system? Maybe that's a new thread...

Thanks Lumpy

 

[cjTango]

Transmission controlled spark switch.
Used on AMCs from 1974 till forever.
6 cylinder and V8 models
Boneyard ?

What does the spark system do? From the vacuum diagrams (and from what I've learned) the spark-vacuum operated system advances the timing of the engine when you're asking for a little more from the beast.

That said, is this switch connected directly to the spark port on the carb?

Thanks!

 

[Lumpy Grits]

When was the last time you replaced the fuel filter and checked the float bowl level?
Have you confirmed ign timing? How hot does the coil get after a 5-10 mile drive? Can you hold your hand on it??
Good to hear you don't have to SMOG test any longer. My son had to play the game when it was at '73 and older.
LG

 

[cjTango]

Changed both the line and carb fuel filters about 10 miles ago. Haven't checked the float bowl level. I'll check that and the carb accelerator pump as well.

I need to check the ignition timing as well. I wanted to start with the assumption that the ign system was fine (since I drove it before), but I'm finding more and more that I can't take anything for granted with this machine.

I'll check and report...

Thanks again.

 

[Lumpy Grits]

You also want to check fuel pump psi and gas tank venting.
LG

 

[Posi]

What does the spark system do? From the vacuum diagrams (and from what I've learned) the spark-vacuum operated system advances the timing of the engine when you're asking for a little more from the beast.

That said, is this switch connected directly to the spark port on the carb?

Thanks!

I understand it to be the opposite way, that it doesn't advance the timing.
It's all to do with lowering emissions.
When the solenoid vacuum valve is energized the vacuum from the carb to the distributor is blocked (no advance). The carb to distributor vacuum is then vented through a port in the valve. When the valve is de-energized the ported vacuum is applied to the distributor again restoring normal vacuum advance.

 

[cjTango]

I understand it to be the opposite way, that it doesn't advance the timing.
It's all to do with lowering emissions.
When the solenoid vacuum valve is energized the vacuum from the carb to the distributor is blocked (no advance). The carb to distributor vacuum is then vented through a port in the valve. When the valve is de-energized the ported vacuum is applied to the distributor again restoring normal vacuum advance.

You're right. Just had to wrap my head around it. Thanks a ton!