Just wondered how to check the vacuem advance on my car, and if I wasn't getting any, what would some symptoms be?? Having some strange problems with the car.... shuts off when using power brakes or steering, have to turn idle way up, runs like a dog....
Help?

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Julie
'71 Chevelle
http://www.geocities.com/MotorCity/Boulevard/7827

Sounds like a vacume leak or incorrect inital timming.

You can put a vacuum pump with gauge (hand pump kind) on the advance canister and see if it leaks down. You can also monitor the running engine with a timing light and pull the vacuum and watch the timing mark move. Careful here 'cause you can damage the diaphragm if you get too tough on it. If you have the dist cap off you will be able to see the advance move the plate as you pull a vacuum on the canister. You are probably using "timed or ported" vacuum to trigger this. This means at idle you won't feel much of a suction from the hose because the source is above the throttle plates. If you are using non-ported vacuum, with the source below the plates just like Power Brakes, etc. you will be able to "feel" the pull from the hose and the idle will change speed when you pull the hose off. As to which way to hook it up, user's choice. Everyone has their own opinion on that. Most factory setups are hooked up to the one above the plates. (Emmisions, mileage, all that) Normally if an engine is modified people try both and go with the best result. A quick and dirty test is the long hose to the canister and suck on it. If the plate moves any, its probably good. Not a pretty or tastey site, but it works.

Bradley handled that topic mightily, but the problem sounds like a leak, not your advance. Lack of advance wouldn't cause such problems at idle or off idle. A leak most definitely would. As would incorrect ignition timing and improperly set idle curcuits.

[This message has been edited by Gene Chas (edited 07-28-99).]