does the coil need to be grounded

[oldmopar]

With the nice weather we are having here I was out trying to start a pending project (46 dodge truck) was not getting any spark from coil. Had one wire to the disributer the other directly to the battery. Tried 2 coils not 100% sure they are good but should have got something. Now as I sit here and think I had the coil on the tire never thought about this before but does the coil need to be grounded since it has neg and pos going to it.

Ed

[55 Fargo]

The circuit needs to be grounded, is the engine out of the truck, the wire from the - side of the coil to the igniton switch, or solenoid circuit, this would be ground already, or should be. The other + goes from the dizzy to the coil. Check the high tension coil wire for continuity. If it is good, crank the engine, check high tension wire from the coil to the block and see if you get a good spark up to about 3/16 of aninch, if weak or no spark could be your answer.

Are your points in good shape, are they gapped at .020, is the rotor,cap and condensor in good shape. Are the plug wires in good shape, are they in the proper order on the cap, are the plugs clean and gapped at say .025 to .030.

Did you pull the dizzy out at all, is it in the right position, if it was pulled out, and is supect, just pull it back a bit an turn the rotor 180 degrees, they only go in in 2 positions.

Place the coil onto the engine or in it's bracket and try that way.

Let us know what happens. Also with the ignition switch circuit in the on position, use a circuit tester and see if you even have juice flowing to the coil wire at the terminal clip, if no juicey, no sparky, no starty, cuz no firey.......Fred

[oldmopar]

I had the neg side right to the battery and pos to the distributer so I will have to look further in the distributer maybe a bad condenser,pigtail or points. It looks like everything was replaced in the distributer but that does not mean it was done correctly. This really is a future project everything will be replaced once I get started have to finish the 52 Plymouth 1st. I was just playing today almost 60 down here.

Ed

[oldmopar]

The coil has 2 circuits with a common point inside the coil.

With the vehicle wiring unhooked, primary should read about 4 ohms according to my Chilton's.

Secondary 4,000 to 10,000.

So then using those number I can check a coil to see if its good never realized it was that easy.

[Jerry Roberts]

Testing the coil ; Turn on ignition switch with the points closed . Remove the high tension cable from the center socket of the distributer cap , and hold it 1/4 to 3/8 inch away from a clean spot on the engine . If the coil and other units connected to it are in good condition a spark should jump as the points are opened . To test for grounded windings ; Place one test clip on a clean part of the metal coil housing . Touch the other clip to the primary and high tension terminals . If the test lamp lights or tiny sparks appear at the points of contact , the windings are grounded and the coil shoul be replaced .

[Plymouthy Adams]

Ground is by way of contact points...basic coil should read on the primary side about 1.2 ohms..and in Shels case he may have a 12 volt coil with internal resistance is why he is reading 4 ohms. We want to keep current down on the coil while providing enough for operation...so the nominal 6.8 volts of a good charging system with the coil impedence of 1.2 ohms will give us current of 5.6 amps now take that same coil and put it on 12 (nominal charging output of 14 volt) we are drawing a whopping 11.6 amps..thermal runaway here folks and eventual shutdown..however we add a ballast resistor of 1.7 ohms and now we have 14 volts divided by 2.9 ohms and we are now back in perspective with current drain of 4.8 amps. Given the coils that use no ballast..we have an industry range of 3.2 to 4.0 ohms. For those that use the external ballast coil of 12 volt will allow use on standard 6 volt operation without fear of over current or need for resistor..and those that upgrade to 12 volt and use the external resistor and by-pass gets the advantage of a huge voltage boost during start and normal output voltage on the run circuit.