Technical Vacuum Advance

[Hyypia]

I need toask about vacuum advance. When the car is on idle, the vacuum advance port has vacuum pressure but my limited general knowledge is that the vacuum advance is ported meaning it draws air when you press gas or the throttle opens but not on idle. Could you please advise if the carburetor is okay or having a vacuum leak?

 

[bugsymike]

I need toask about vacuum advance. When the car is on idle, the vacuum advance port has vacuum pressure but my limited general knowledge is that the vacuum advance is ported meaning it draws air when you press gas or the throttle opens but not on idle. Could you please advise if the carburetor is okay or having a vacuum leak?

It can be tested in various ways, but easiest for you is pull the vacuum pipe off when engine running and see if engine note changes when you put your finger over the pipe and also if it runs worse with open pipe and if still the same when connected that would indicate a leak.
Older cars with vacuum advance on the distributor the diaphragm often fail.
You can test that by putting a pipe on the vacuum unit on distributor and sucking then sealing it with your tongue, if good then when you release your tongue you will feel the vacuum working.
Some cars with brake servos if leaking will make engine run poorly/uneven, the other clue with that is the brake pedal can feel hard but not easy to stop the car.
With brake servo vacuum if fitted you can test it by with engine off pump brake pedal several times so vacuum is exhausted, then hold brake pedal firmly and start the engine, if good the pedal should go down a little as the vacuum servo is working.
The job of a brake vacuum servo is to reduce the effort on the brake pedal when you press the brakes.