How To - Check Coil Polarity

[mthieme]

Coil polarity is very important. If reversed, the spark plugs may demand 30-40% more voltage to fire. On most CD systems, there will be no spark.

Method 1 - With a DC voltmeter, connect the positive lead to a good ground. With the engine running, momentarily touch the negative lead to a spark plug terminal. The needle should swing upscale. If the needle swings downscale, the polarity is reversed.

Method 2 - Disconnect a spark plug wire and hold the metal wire connector end about 1/4" away from the spark plug terminal. Crank the engine with the ignition switch on. Insert a pencil tip in the arc stream. If the arc feathers towards the spark plug, the polarity is correct. If the arc feathers towards the wire, the polarity is reversed.

 

[ooldschooll]

Re: How To - Check Coil Polarity

http://www.outboard-boat-motor-repa...on 3 HP 1952-1967 Ignition System Tune-up.htm try this it should help

 

[Chris1956]

Re: How To - Check Coil Polarity

OK - I'll bite. How does the polarity get changed? Most if not all american-made engines are negative ground, and most if not all coils have one side grounded. The side to be grounded is usually quite obvious.