Old vw bug ignition coil noise old guys

Hey Guys.

my memory is shot and i barley remember there being a fix for the old vw bugs ignition coil noise.

its not an alt whine, its a tick that increases with rpm. Cust has high end coil and ignition system, also all grounds are good. Noise is coming from amp while on and no rdas plugged in.

Me and my other senior installer remember something about a polarized cap of 47 or 4.7uf being attached to the ignition coil or something.

any help is appreciated.

I'm not sure of the value for the capacitor. 4.7 is probably about right. The cap goes on the POS side of the coil.

I worked on Bugs at a California dealership for most of the 70's. I don't recall any noise problems with those old-school POS's. I have in more recent history dabbled with vintage Corvettes that have plastic bodies. Vintage Sting Rays have noise suppression caps on several things like turn signal flasher, ignition coils.

An interesting experiment would be to temporarily power the amp from an external battery. If the noise is still there, it is being "transmitted" through the air. If it goes away, it's being transmitted through the power wiring. If the caps don't work, perhaps a DC/DC converter for the ignition system would stop the transmission of the ignition pulses into the power wiring of the car / amp.

If the noise is only on the radio and not other sources it is likely ignition noise. Make sure the antenna is properly grounded and the connections are good,
If the noise is limited to only the radio, the capacitor may help, but you should also make sure that all plug wires are good. The caps I used back in those days were inline. You cut the ignition feed wire to the distributor cap and wired it inline. Some plug wires are not designed to reduce RF noise. An easy way to check if you have bad plug wires is put the engine on a scope to check plug wires. If you don't have access to a scope, open the hood on the car and start the engine. Pull another car along side and turn its radio to a FM station. Turn the engine off in the other car and just listen to the radio. If the other car has engine static you probably have a bad plug wire or wires.


-------------
sparky

4700 microfarad 25v or greater. Greater on the voltage. Possible bad plug wire or try using resistor plugs.