Car Stereos: crackling noise on cd, crackling noise, gm hei

Question
QUESTION: I installed a pioneer mod DEH-P5200HD radio in my 1946 ford. The radio and cd"s play fine when the engine is not running. With the engine running the radio still works fine but there is a crackling noise over the cd songs.Seems to get more frequent as rpm"s increase. All the wiring in the car has been replaced and extra attention to grounds. I tried a filter on the feed wires but no change. The car has a variable speed radiator fan controll and multiple discharge ignition controller. I can not understand why this is happening.
Thank you for any help,
Fred

ANSWER: Hi Fred,

Old cars were not very well electrically shielded and the old motors with their old school carburetors, and distributor caps lead to lots of EMI in and around the vehicle.

First thing I'd check is not just the grounding at the deck, but the car's grounding aswell.  Make sure the negative battery post is well grounded with a heavy gauge wire preferably to the engine block somewhere, to the transmission somewhere, and at various points throughout the car's chassis.  The continuity from the black wire going into the deck and the ground on the battery should be as close to 0ohms as possible.

Beyond that, your next bet might be to get some shielded speaker wires to carry the signal.

Justin

---------- FOLLOW-UP ----------

QUESTION: Justin
Thanks for your help. The solution was to apply dielectric grease at the center post of the distributer rotor and the outer tip of the rotor. I need to replace my sparkplug wires on my steet rod with a GM hei ignition. Can you suggest a economical set?
Thank you for your help
Fred

Answer
Hi Fred,

This is a question for the automotive section, since you're getting into mechanics.  (This is just the car audio section.)

That said, needing to apply dielectric grease to a distributor and rotor would suggest they aren't making the kind of electrical contact you'd like anymore, and it might be time to replace them.

Justin