‘59-‘60 tri m-power vacuum switch

[David Greenburg]

WTB working vacuum slider switch (actually a valve).  This is the Trico part that mounts on the center carb.

[76eldo]

They are on ebay at times and there is one on there right now.  You need to make sure it's the correct Caddy one though although I think any of them should work.
What's wrong with yours?

Brian

[David Greenburg]

Brian:

Not sure exactly what is wrong with mine, other than it does not cause the diaphragm to move when it’s supposed to (diaphragm works fine when vacuum is applied directly).  I’ve been watching eBay, and as of last night, could not find one.  I found one that had been listed previously and apparently not sold.  So I emailed the lister.  He promptly relisted it ( probably what you saw this morning), and I bought it.  So hopefully all is good.

[76eldo]

Does the slider move freely?
If not soak it in penetrating oil for a day or so.  It's easy to test by blowing air into it with a vacuum hose by mouth and moving the slider to see if the air comes out of the port that goes to the vac diaphragm.  It could have something blocking that small orifice.  The Pontiac ones have a much larger hole.  I believe that would activate the secondaries quicker.
A mechanical linkage would make a lot of sense here if you want max performance.  Under that air cleaner it may be invisible and easily reversible.

Brian

[David Greenburg]

Thanks for the suggestions.  It does move freely, and I’ve tried cleaning it in the past.  I agree a progressive mechanical linkage would be an improvement, but I’m not enough of a carb guy to feel confident about building my own, and having someone else do it would be a pretty expensive exercise in parts and labor.  I take it you are still running the vacuum system on yours.

[76eldo]

David,

I am running the stock parts with the tiny orifice in the tri power switch drilled out a bit.

Brian

[David Greenburg]

Brian:

The switch I picked up fits and appears to work, but just has a “full bore” opening instead of the pinhole orifice of the original. Do you see a problem with that?   

[76eldo]

I read somewhere that the Cadillac Tri Power was "calibrated" with the tiny orifice so that the "Cadillac driver would feel a smoother transition to wide open throttle" as opposed to say a Pontiac or Oldsmobile unit.

Bigger opening should equate to more vacuum pulling the diaphragm faster and harder for better acceleration and that  -H U G E-  sucking sound of the air rushing through the snorkles.

Try it and let me know what you think.

Brian

[David Greenburg]

I drove it for a bit last weekend, and while it seemed to run better, I didn’t get that big sucking sound or any obvious jolt. Part of why it ran better is likely due to the old dead switch contributing to a vacuum leak. But the car is back on the operating table; the rebuilt water pump had a slow leak from the rear cover plate, so I pulled the pump to tighten the bolts, and despite following the torque spec, managed to snap the head off one of the bolts ( ok; I will admit it’s a Harbor Freight wrench).  So hopefully back on the road  to check out the tri-power this weekend, weather permitting. Some serious rain headed our way.

[76eldo]

David,

It's pretty hard to not hear the intake roar when the two end carbs open up.

There are adjustments on the switch relative to positioning and the angle of the tab on the carb linkage that pushes the slider down on full throttle.  You may also have a vacuum diaphragm problem.

I'd have to hear it and drive it to diagnose it.

Brian