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According to the book i have the timing should be set 6 degrees before top dead center. When I put the timing there using a timing light the engine pings a lot. The brass adaptor between the carb and vacuum line was missing so I installed a new 1. The vacuum advance works when I put vacuum to it. The mechanical advance in the distributor works when I move it by hand and it returns as it should. The car is a 1952 Mayfair.There was a broken vacuum line from intake to fuel pump so I replaced it. The engine idles very smooth like a Packard should. When I got the car it pinged bad on acceleration. When I checked the timing it was no where near the marks. Thanks for any replies

Check the dwell. It should be stable with increasing rpm. If it isn't the distributor is worn and can be generating a rogue spark.

The most likely culprit is carbon. Check the compression. If it too high the motor has a carbon problem. There are ways to clean combustion chambers without pulling the cylinder head. You can get over the counter advice from a decent auto parts store. I will reserve saying anything more given these methods are not fool proof.

A third possibility is the vibration damper is shifting with the motor running. This can be checked using a vacuum gauge. With the motor running advance the timing to the highest reading on the gauge then back off two inches HG on the gauge. Recheck the timing at this setting. If the timing marks are off significantly the damper is giving you a false timing setting.

When they are right the exhaust has a somewhat throaty sound to it.

Good Morning...Just a humble comment...Our 1949 288 was set with a timing light and then 'adjusted' for modern 87 octane gasoline by ear of an old guy! Tim is certainly right about the distributor. It's cam may be warn out, the points block may be warn out...sometimes if it pings, retard the spark a bit and drive it around the block and maybe it takes a couple of passes to make her happy. Ernie in Arizona