Packard Forum Index » Post-War (1946-54)

i was thinking its sum of both

Here is some good Info about vac and centrifugal advance.
camaros.org/pdf/timing101.pdf
There are also some other good Tech articles there.
I would be interested to see an ignition curve for the Packard distributors.

You never said if you checked your vacuum advance. The best way is with a hand operated vacuum pump with a gauge. Connect the pump to the chamber and pump. It should hold the vacuum reading and not bleed down. If the vacuum does not hold, and your connections are tight, then your chamber needs rebuilding. Another way is to suck on the tubing causing a vacuum. With the tubing connected to the chamber and off of the carburetor end suck on the tubing and place your tongue over the tubing. You should feel the vacuum. You should feel the vacuum pulling for as long as you have your tongue over the tubing. A leaking vacuum chamber can really affect engine performance including to contributing to over heating.

And yes, it is the total advance as provided by the mechanical and vacuum components.

(o{}o)

took me three days to think of this but, disconnect vacuum line set at 6 btdc at 500 rpm, while watching pointer increase rpm watch and note range of increase perhaps 16 degree increase, have to figure some way to measure accurately, hot rod chevys have that aftermarket tape with scale for balancer, then I can judge the mechanical advance system. for example if the mechanical weights are stuck there would be no change and I would have to set timing at 6 plus 16 which is what appears to be the case. Now have to find the time for me to try this.

did the above (prior post) test on vacuum unit already seems ok

Your comment about being too far advanced may have solved my problem of just barely cranking initially, but after 8 sec. it starts and runs fine. Must check the timing soon! Thanks