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vacuum starter switch testing

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I'm getting a n.o.s. vacuum starter switch for my 35 Buick and wanted to know if there's a way to test it before I install it. Also,does anyone have any original linkage for it? I can probably make my own if not.Thanks,Greg.

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I can tell you how I tested the vacuum starter switch on my 1941 Buick. I don’t know how similar they are.


Mine is attached to the front carburetor. The throttle rod that chokes the carb when you press on the accelerator pedal passes all the way through the carb and terminates inside the vacuum switch. The rod has an eccentric on it. When the pedal is pushed to the half way point the eccentric releases a ball within the switch and that makes the contact between the two wires going to the vacuum switch. As soon as the engine starts the newly created engine vacuum sucks away the ball and the starter circuit is broken.


To test the switch before wiring it to the starting circuit do this:


With the engine off use a multimeter to test for continuity between the two terminals on the switch. There should be none (infinite resistance). Now depress the accelerator. At about the half way point the meter should beep and indicate 0 ohms. Next start the engine the way you usually do (starter button?). Again test for continuity between the two terminals but this time with the engine running. There should be no continuity.


If you got these results without connecting the switch to the starter circuit it is very likely it will work when you connect it.

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Quick test to see if it’s bad:  put it to your mouth and suck on it.  If you can pull air through it, it’s bad.  If not, it will most likely work - put it on and try it.  I can’t help you with the linkage. 

Now be easy on the comments 😉



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