Packard Forum Index » Pre-War (1899-1942)

I took the 41 for a test drive it went pretty well.the longer I drove it the better it seemed to run.I felt that possibly the timing was off do to bogging down when first accelerating.Today I checked to see if the vacuum advance was working it was not so I put a vacuum gauge on at the carb where the vacuum advance hooks up and there is no vacuum there.I checked and cleaned the elbow at the carb and also took the carb off and sprayed carb cleaner through the vacuum hole it was open.I put the carb back on still no vacuum. There is around 18 to 20 inches of vacuum at the intake.The carb is the correct aav 26 for the car.I thought maybe the throttle plates where open to far but they where only open a crack at idle.The engine idles very smooth so I dont think there is a vacuum leak.So why is there no vacuum? Also there is a plug at top rear of the intake if I put a vacuum line from there to the vacuum advance would that do the same job.

Look to see if the vacuum opening in the carburetor throat is above or below the throttle plate when at idle.

Check for vacuum at the carb fitting as the engine speed is increased above an idle when it should come into play.

I dont know why I did not throttle up the engine. I tried it today and there is vacuum there with engine throttle up.So the vacuum hole must be on the top of the throttle plate. I guess I was thinking of 60s and 70s cars when you pull off the hose for the vacuum advance there is vacuum there even at an idle.I put a small hose on the vacuum advance with distributor cap off and i can see the breaker plate move and it holds vacuum. Also checked the mechanical advance it moves and returns as it should.