69427

The capacitor on the C+ terminal is there to reduce/prevent noise being induced into the vehicle harness and into the radio power supply. Once you have the cap in place then you need to address the plug wire issue. Low resistance/reactance plug wires allow a high current spike to occur once the plug arcs over. This high current pulse radiates everywhere, both into the wiring harness and into the antenna. If you can slow down/reduce the plug current spike it should help reduce the noise in the radio. Let us know how things are when you change the plug wires.

Pilot Dan

I am surprised nobody asked if you were running a stock or aftermarket (newer) radio, some of which require additional wiring and grounds.

Frankie the Fink

The aftermarket radios I have run have a big bolt that goes into the PS side mount point and thoroughly ground the case....the AAR repro for instance; I guess there are others that might float in the mounting and require a separate ground... Its also possible the radio has a defect as the Bluetooth works whereas broadcast stations do not (without noise)...

This last factor is a key clue - it may preclude noise introduced into the power line...

jim lockwood

That's not quite a fair comparison. Bluetooth thingys operate in the 2.4GHz range while FM broadcast is waaaaay down there at 0.1 GHz. It's unlikely that any noise source, such as ignition, could generate any noise energy up at 2.4GHz.

Jim

Frankie the Fink

That is true.

Its easy enough to tell....if the radio has an AUX or pin jack just play some tunes through that for a bit and see if the whine is there

Frankly, I could have changed the plug wires in the time its taken to produce this thread...

To the OP: I wouldn't worry two nits about resistance plug wires creating "weak" spark....its a non-issue for about 98% of our cars running the streets...

jim lockwood

And I just thought about something else which would make Bluetooth thingys immune to ignition noise...... in all probability they communicate digitally which is about as noise-immune as you can get.

AM and FM broadcast both use analog technology, which is inherently more susceptible to radiated noise.

Jim

Jackfit

All these little things.....lets see the car....some video of it moving.....I think it is all made up.......lol......Ingrid , take some pictures while he is out.......

Jack

alexandervdr

all the comments make sense, I am now waiting for the higher resistance spark plug cables to cross the ocean (and the customs...)
That may take days or weeks, depending on the temper and mood of the 'red tape' .

As soon as I have tested them , I will let you know my findings

by the way: did I tell already that I installed the distributor top ignition shield , did not make any difference.

Avispa

Still trying to figure out how the OP is having noise trouble with FM (he didn't say whether AM was affected). FM is essentially immune to most electrical noise from sources in the car like plug firing and power switching. All those noise suppression capacitors are for AM, which will pick up any amplitude-change electrical noise that has frequency components in the bandwidth of the 455 KHz intermediate frequency amplifier. Unshielded graphite core plug wires usually don't have any effect on FM. A strong AM broadcast signal will usually override noise from unshielded graphite core plug wires.

The OP also didn't mention what kind of "high performance" plug wires he got from Zip. All I could find in their on line catalog were Pertronix wires, which are good ones for noise suppression - graphite center core with spiral wound resistance (nickel chrome or monel) wire covering the graphite. These wires generate less radio noise than uncovered graphite core wires because of the spiral wind of the resistance wire. The field generated by spiral core wires runs along the length of the wire, rather than perpendicular to the length of the wire (the same for graphite core or copper solid core wires).

Something else is going on beside the plug wires and breakerless ignition.

alexandervdr

what I got was "57-74 Performance Spark Plug Wire Set" from ZIP
Item #: M-3962

Avispa

Alexander, I just checked the wire set you mentioned. They're 250 ohms/foot. I'm running Bosch spiral core wires (50 ohms/foot stuffed in correct BBC braided wire shields). I'm also running a mallory unilite module as a trigger and an old MSD 6A analog box to jolt the coil. NO noise on FM or AM. You've got a radio problem. Your ignition mods just don't create enough RFI to put noise in a properly working original Delco radio with factory ignition shielding. Especially on FM.

alexandervdr

Thanks for this detailed info. The braided part of your set-up may have an impact? Note that I have a modern Pioneer in there. Thats' the one that 's having the noise problem.
Where did you get the 250 ohms/foot info of the wires I bought? It's not on the ZIP site.

426 Hemi

Maybe the alternator/regulator is inducing some noise. Could pull the belt and test real quick.

Avispa

it's on their mobile site at

http://www.zip-corvette.com/57-74-performance-spark-plug-wire-set.html

alexandervdr

I tried it all, nothing worked (including going to the high ohm spark plug leads).
The final check was the antenna itself that had a problem. I installed a new one and that was way better, waiting for better weather to fully check and report cause rain is pouring like hell, and will do so for the next couple of days.
In case you are wondering: I installed an 'indoor' antenna, although I had tested it something went wrong

iamq

I've been looking for one of thoes indoor antennas. Where did you get it?

alexandervdr

there is plenty on eBay type 'indoor car antenna'

alexandervdr

some update. Even the replacement indoor antenna did not work out well, was better still very noisy. So I Installed a (retracting) antenna in the rear (means taking off exhaust...) and that did it. Difference in reception quality is hughe. There is still some light ignition noise especially when station signal gets weaker, but only audible when at idle. Above that , car noise takes over