1941 Cadillac radio static

[C Gorgas]

What could be causing excessive static on the radio when the engine is running. I have the condenser on the generator, there is a ground strap engine to frame, the antenna is grounded and I placed a condenser between coil & distributor. All of this has no effect in reducing the engine static. Any ideas? Chet G.25441

[Paul Phillips]

You should have ground straps from each head (rear-center bolt) to the firewall when you have a radio.  Be sure that you have clean metal-to-metal contact with those grounds and all others.  In theory, poor quality connections for the spark plug wires can contribute, but that is less likely.  Be sure the antenna ground is solid between antenna & body metal.  Finally try a filter at the power inlet to the radio.

Hope this solves your problem!

Paul

[bcroe]

Besides good grounding as describes above, you could swap out the
noise capacitors mentioned to find a bad one or a bad ground. 

Perhaps with the engine off, its the radio vibrator power supply. 
Perhaps listening to the noise, you can tell if its from the ignition or
the generator.  Then that area can get more attention.  Any large
gaps in the plug wiring will cause issues.  Bad wires, solid metal wires,
a badly phased rotor.  Some of us (radio amateurs) add extra shielding
to pretty much eliminate any electrical noise from our own cars. 
good luck, Bruce Roe

[Brett Baird]

41 Cadillacs with radios also had a ground strap from the firewall to the hood.

[bcroe]

If none of the above solve the problem, I would take the belt off the
generator to see if it makes a big difference.  Bruce Roe

[Mike Wenrich #1666]

Any idea where the ground strap to the hood was attached?  Firewall to hood bracket maybe?

[Brett Baird]

A picture's worth a thousand words.

[bcroe]

A picture's worth a thousand words. 

That's cool.  But for maximum effect, I would have used one on each side,
as far apart as possible.  Bruce Roe

[Brett Baird]

Well, for authenticity purposes, the photo posted is how Cadillac did it.

[Steve Passmore]

That's strange. I have owned 7 1941 Cadillacs, all but one with factory radios and never seen this earth strap on the hood. Could all past owners have removed the straps?? would be a bit of a coincidence and why on the hood?  Can't say if the radios worked without it as I have never had a radio that would even switch on.

[bcroe]

That's strange. I have owned 7 1941 Cadillacs, all but one with factory radios and never seen this earth strap on the hood. Could all past owners have removed the straps?? would be a bit of a coincidence and why on the hood? 

The radio will work without the strap, but possibly would pick up more
static on weak stations.  The idea is, the hood forms part of a metal box
to contain the static generated by the engine.  But the gaps between the
hood and the body tend to negate the shielding effect.  Connecting them
together where practical helps.  Bruce Roe