NAPA plug wires good to suppress radio noise?

check main ground, radio ground and antenna ground before changing the plug wires

I like to buy my plug wire on the roll, and use the resistor terminal. Usually if you use the resistor plug in a vehicle with a steel firewall and hood you get little noise.

Are you sure it's ignition noise and not the alternator?

NAPA people generally don't know their ass from a hole in the ground, although there are exceptions.

First, make sure your spark plugs have an 'R' in their model number. That means they are a resistor type spark plug that reduces radio ignition noise without reducing spark output in a significant way.

For spark plug wires, make sure to avoid ANY ignition wiring sets that brag about low resistance since that is, like on the spark plugs, needed to suppress AM radio noise. Due to how wiring and Ohm's law works, the resistance needed in ignition wiring and spark plugs to eliminate ignition noise in an AM radio does not significantly reduce the spark intensity. There is so little current flowing through ignition wiring that even the normal high-resistance in ignition wiring does not significantly reduce the voltage. And don't worry, that extra resistance is PURPOSELY added to the wiring... it costs more to make it that way than it would with lower resistance wiring.

So go with standard carbon-impregnated ignition wiring sets and avoid at all costs any so-called "performance" ignition wiring set that talks about its lower resistance even if it also says it has some lame "spiral-wrap" technology to reduce noise.

Using standard resistance-type spark plugs and ignition wiring should take care of your ignition noise in your AM radio.

Jerry

James Nipper wrote:

I have always had excellent AM radio performance with solid metal core wire with resistor plugs and the proper coil resistor value. What resistance does is lowers the Q of the tuned circuit formed by the plug, wire, and cap, which is a tuned LC circuit at _some_ frequency.

This makes the circuit lossier for RF "floating around".

You will be interested to know the late Dave Blanton of Javelin Aircraft advocated straight metal plug wire for his Javelin Ford conversions , as in his 175 Skylark testbed. The ADF worked fine for listening to Royals and Broncos games just fine. So did the VHF AM nav and com radios.

Thanks for these very nice replies. How would one tell if the noise is the ignition, or the alternator???

It does vary of course with engine speed.

--James--

Use a portable transistor radio with a ferrite loopstick antenna as a direction finder to find the noise, if a thorough ground check and retightening has no effect. You can of course disconnect the battery, then unhook the alternator and restart the engine on battery power or disconnect the belt to see if that does it.

Ever hear a motorboat in the TV or radio? That is spark noise. Like a bzzzt noise. Alternator noise is a whine.

Mike

James Nipper wrote:

Good replies on making distinction between alternator whine and ignition noise. This is definitely ignition noise.

I will follow up on the points suggested.

Thanks everyone !!

--James--

I've never seen ferrite lipstick, what's it look like?

And, how does it make the radio work better?

You missed another post where I asked what ferrite lipstick looks like ...

Nevermind, it's not funny anyhow.

Great, now my friends are hiding me in the closet.