Re: MSD Problems
Listen closely weedhopper (and don't forget to shave your head), and I will give you the secret of diagnosing ignition noise vs. current cycling noise on vehicles....
Pay attention, cause this takes lots of time to type....
Chasing radio noise problems can get frustration.
First, isolate the source if possible.
If the noise problem vanishes when the jumper wires are installed (converting to standard ignition), then the MSD unit has introduced a factor that directly or indirectly causes the interference.
This could be a breakdown in existing ignition and/ or the introduction by the MSD of higher energy output.
Check the following items first:
1. The automobile chassis and engine MUST have a good common ground.
A grounding strap from the frame to the engine will insure this.
All radio, tape, and CB systems, ect. must have a good common ground connection.
2. The MSD heavy black wire must be properly grounded to the battery if possible, or the engine ground cable.
3. The mounting location for the MSD unit must be as far away from the antenna (including the antenna wire, and imbedded windshield antennas.
IDENTIFYING TWO TYPES OF RADIO NOISE
1. Radio Frequency noise (RF) is generated by the ignition secondary (spark plug & coil wire).
This noise is radiated into the air and picked up by the vehicles radio antenna.
RF noise will affect the AM band and the noise will be very loud between radio stations.
The FM band may be affected slightly.
RF noise will not be heard when playing a cassette or CD player.
2. Supply Line Variations are caused by varying loads on the vehicles supply voltage.
These varying voltages are amplified through the radio's 12 volt supply wire and are heard on the speakers.
Supply Line variations will affect equally the AM band, the FM band,& cassette or CD player.
SOLVING RADIO NOISE PROBLEMS
1. To solve the RF noise use dielectric grease on the tip of the distributor rotor.
If the noise persists, check for cracked, burned, or other wise damaged spark plug or coil wire.
High voltage ignition wiring must be in good condition with no exterior arcing or voltage reduction to the spark plugs.
Make sure the insulation is not cracked.
A night check under the hood will usually indicate a wiring breakdown.
If you see a blue corona around the wires or arcing to ground, the wires should be replaced.
DO NOT replace with Resistance suppression wire.
Use a magnetic suppression wire with a Helically wound core. (MSD 8.5 MM are the best)
2. Supply line noise may be eliminated by using a capacitor (Best I've used is MSD P/N 8830), on the heavy power supply wires coming from the MSD unit.
The length of the power supply leads from the MSD tot he capacitor should be as short as possible. (Mount the capacitor very close to the module).
Interference on radios can often indicate the beginning of a problem in normal wear on plugs, high voltage wires, cap & rotor, points, ect.
Adding the higher energy output of the MSD may indicate a part of the ignition system should be upgraded and/ or replaced.
"I Have The Body Of A God... Buddha"