View Full Version : MSD 7Al & Resistor plugs

08-29-2003, 08:39 PM
can resistor spark plugs be used with a 7Al??? This is a race only application, I think a non resistor plug should be used, but my son keeps installing resistor plugs. It does seem to run ok with the resistors, this is a small block Mopar.

08-30-2003, 12:44 AM
Yes, you can run resistor plugs with the MSD 7AL-2 Ignition. Resistor spark plugs are generally used on vehicles with onboard electronics to reduce the amount of RFI generated. On a race application most people try to reduce the total amount of resistance to get the most voltage and energy across the spark plug. Super Conductor Spark Plug Wires like MSD's have only 50 ohms per foot of resistance, but also maintain a high noise reducing capability. For learning purposes, measure the resistance of a spark plug with an ohm meter. Place one of the test leads on the end of the plug where the spark plug wire boot attaches, and the other test lead on the center conductor where the spark plug gap is. You will see that there is quite a bit of resistance in the spark plug.

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