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

I have a 1954 Convertible with the 359 engine and the original aluminum head. I'm using Champion RJ8C spark plugs, which would seem to be the lineal descendants of the J8 listed in the shop manual. I use premium fuel. The pinging happens only when under load, never when revving in park or neutral. I can eliminate the pinging by retarding the distributor several degrees, but the idle is very unsteady, vacuum gauge fluctuates between 13-15 inches until the RPMs go over 600. I have disconnected and plugged the vacuum advance, that made no difference.

I'm wondering if a colder spark plug might help, but it looks like Champion doesn't make a colder plug. The only other plug they recommend is the RJ12YC; the 12 in the part number indicates that it is hotter than the RJ8C. If anyone has solved this problem, I'd appreciate knowing what the solution is. Thanks.

Does the pinging occur at highway speeds and climbing a hill? And if you back off the throttle a bit it will stop pinging?

In my 1954 Patrician, I use Fire Injector multi-tip plugs that have been in it since the early ‘80s and never a ping. Unfortunately I don’t know of a source today as these came from JC Whitney!