Ignition shielding

[Sam Cogley]

The ignition shielding for my 77 is long gone (it was missing when my dad bought the car 22+ years ago), and as a result there has always been an annoying high frequency whine in the radio. I'm curious as to what any of you guys might have done to shield the ignition system without using the stock parts.

 

[69427]

High frequency whine in the radio is usually caused by the alternator. Are you sure it's ignition related?

 

[mrvette]

High frequency whine in the radio is usually caused by the alternator. Are you sure it's ignition related?

Alt wine sounds like a sine wave, like you hearing getting checked out....

ignition sounds like static from a thunderstorm in a old AM radio....


Old tech heads can recognize the diff in a second....

:lol:

 

[DC3]

You can pull the alternator belt and run the engine. If the noise goes away, it is related to the alternator.

Double check that all your grounds are good but especially the radio ground, the alternator ground, and the main battery cable where it grounds to the frame.

If it is alternator noise they make a filter that attaches to the alternator and they also make a noise filter than goes inline of the power supply wire to the radio. Car stereo shops fight this battle all the time, they may have some suggestions as well if you have a good one near you.

Here's a link to the alternator filter: http://www.parts123.com/parts123/yb...RA0TIC7N10817839880a~Z5Z5Z5YES~Z5Z5Z50000050G

If it is ignition related, there may be a capacitor in the wiring harness near the key side of the coil (not sure about your year model). It helps with noise and may need to be replaced. As far as a non-stock shield, you may have to experiment with some type of fabricated metal shield around the distributor.

DC

 

[Sam Cogley]

Grounds are all good, I've rebuilt most of the electrical system (including the alternator and all of the attendant wiring) myself. I'll double-check the radio's, though.

I can't pull the alternator belt - the car has a serpentine system.

The noise doesn't really have that "hearing test" sine-wave tone, but it's also not really the "AM storm" type sound, either - though closer to the latter. It rises in pitch with the engine RPMs, which could be either the ignition or the alternator.

It's done this through three different alternators (four, if you count the CS144 pre- and post-rebuild) and two grounding schemes for the charging system.

 

[mrvette]

OK, you calling it a 'radio' is it the stock factory GM radio? or an aftermarket unit?? IF it is aftermarket, does it have a separate amp from the preamp/control center??

 

[BBShark]

I can't pull the alternator belt - the car has a serpentine system.

WTF? Impossible to remove serpentine belt?

 

[Sam Cogley]

I can't pull the alternator belt - the car has a serpentine system.

WTF? Impossible to remove serpentine belt?

I can, but it will disable the water pump with it.

OK, you calling it a 'radio' is it the stock factory GM radio? or an aftermarket unit?? IF it is aftermarket, does it have a separate amp from the preamp/control center??

The stock radio was long gone when my dad bought the car years ago. It's an aftermarket JVC cassette deck, no separate amp. I used the same cassette deck in a factory modified configuration in the '65 Mustang I owned in HS without issue.

 

[Richard454]

You can pull the alternator belt and run the engine. If the noise goes away, it is related to the alternator.

Double check that all your grounds are good but especially the radio ground, the alternator ground, and the main battery cable where it grounds to the frame.

If it is alternator noise they make a filter that attaches to the alternator and they also make a noise filter than goes inline of the power supply wire to the radio. Car stereo shops fight this battle all the time, they may have some suggestions as well if you have a good one near you.

Here's a link to the alternator filter: http://www.parts123.com/parts123/yb...RA0TIC7N10817839880a~Z5Z5Z5YES~Z5Z5Z50000050G

If it is ignition related, there may be a capacitor in the wiring harness near the key side of the coil (not sure about your year model). It helps with noise and may need to be replaced. As far as a non-stock shield, you may have to experiment with some type of fabricated metal shield around the distributor.

DC

\\
It would be a lot easier to disconnect plug on alt....

JVC cassette - more than likely the head in the tape deck is the PU of the noise...They used to be notorious for doing that...

Pull the radio out- away from dash and see if that stops it.. I'm guessing a wire in the harness is causing the problem.

The Mustang is shielded so to speak by the metal (if it hasn't rusted all away!)- That's why no problems w/ it...


Richard

 

[BBShark]

I can't pull the alternator belt - the car has a serpentine system.

WTF? Impossible to remove serpentine belt?

I can, but it will disable the water pump with it.

Uhhmmmm. If you remove the belt and start the car, you should be able to figure out if the alternator is the problem in less than 30 seconds. If your car will overheat in 30 seconds, you have other (more pressing) problems than your radio.

 

[Kid Vette]

Just pull all the radio garbage out and listen to the beautiful music coming out of the pipes. Your Vette will accelerate faster, stop in a shorter distance, handle better and get better gas mileage.

 

[mrvette]

I can't pull the alternator belt - the car has a serpentine system.

WTF? Impossible to remove serpentine belt?

I can, but it will disable the water pump with it.

Uhhmmmm. If you remove the belt and start the car, you should be able to figure out if the alternator is the problem in less than 30 seconds. If your car will overheat in 30 seconds, you have other (more pressing) problems than your radio.

no shit!!!!

Just pull all the radio garbage out and listen to the beautiful music coming out of the pipes. Your Vette will accelerate faster, stop in a shorter distance, handle better and get better gas mileage.

I installed 6x9's in the back vertical deck of my top hatch, some 18 years ago...guess what, not hardly used once and tunes are absent from my ride....

course at 80 mph and Magnaflow I can't hear anything anyway....


:shocking:hone: