radio install in 31 coupe - sound problem

Tom Bellfoy

Tom Bellfoy

Senior Member
I've installed a new modern JVC brand radio/CV receiver in my 31 Model A Coupe which is converted to 12 negative ground with alternator and I'm having a problem with interference coming from the ignition, dont know if its from the low voltage or high voltage side causing the problem.

I also installed a Napa brand RC1 condensor at the 12 volt ignition coil positive lead to ground and this makes no difference.

My car has the stock distributor, modern points and Motorcraft TT10 spark plugs.

I do not have an AM or FM antenna installed because I do not use the radio portion of the device. I plug in my USB music stick or play a CD. When the engine is not running I get a great sound out of my two speakers, however as soon as I start and run the engine the volume cuts in and out, mostly out .

I tried powering the radio via a separate car battery, also removed the fan belt to eliminate the alternator as a source of the problem, but there was no change to the problem.

I'm suspecting the high voltage side as the source of the problem.

Does anyone in Model A land have any suggestions or experience with fixing this problem ?

Thanks to all.
 
Start by replacing the hi-tension coil wire with a suppressor wire and see what happens. That generally will eliminate a lot of it. There is also a modern cap that is available that fits the Model A/B distributor where you can use suppressor wires from the cap to the plugs too.
 
I have a friend who has several Model A's and uses one of them to go on tours with. He said he got a Hi-Tension coil wire from an Auto Elect Shop and it made not only his Radio work great, but also his CB which he uses on his tours. So I'd have to chime in with Brent. I just talked to my Model A Buddy about this subject the other day.
 
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I would agree that changing out the high tension leads will solve the issue. Its not only a CD player effected by the "Noise" from the ignition. Last weekend returning from Whistler we were trying to communicate between two Model A's with cell phones. The static noise almost made conversation impossible when the cars were running, but no problem when shut off.
 
The whine from the alternator's charging can be surpressed with a "NOTCH FILTER" which is designed to block out the frequency produced by it. A marine electronics shop will be able to provide one for you.
 
Farrell In Vancouver said:
I would agree that changing out the high tension leads will solve the issue. Its not only a CD player effected by the "Noise" from the ignition. Last weekend returning from Whistler we were trying to communicate between two Model A's with cell phones. The static noise almost made conversation impossible when the cars were running, but no problem when shut off.
Click to expand...


Farrell -

Reading your comment made me chuckle.... my model A is so tired and noisy, that the "Model A noise" makes conversation impossible when the car is running, cell-phone or not"...:p


I hope I remember this bit about suppression on the coil wire when I do get modern electronic comm / hi-fi in my Flivver...

:cool:
 
well guys, that was the problem !!! I replaced the coil with with the carbon type and the problem of the sound cutting out had disapeared. I was busy with other things and finally got around to picking up the wire . I want to thank Brent and all of you who shared their thoughts to help me find and fix the problem. this is a real valuable site
Tom
 
Thank you for getrting back to us with the solution. Many times we are just left hanging wondering if the problem was solved and what solved it it it was fixed.
 
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