Arcing from Distributor Coil

[Birdsboat]

When cranking my engine over I have noticed there is arcing coming from just below the lead on the cap on both sides. It is arcing from the neck of the coil where the cap sits and across to both electrical terminals. I have checked the coil body for cracks and also there are no cracks in the cap on the lead.

 

[Bondo]

Ayuh,.... Electricity takes the path of least resistance,....

Those sparks are tellin' ya there's too much resistance in the wires, or cap/ rotor, or the spark plugs,....

 

[Birdsboat]

Should I change all the leads and check the rotor? Am I able to check these parts to determine what needs changing?

 

[Grub54891]

If you haven't tuned it up recently, just change all the wires, cap rotor and plugs. Be sure to use marine grade parts all the way. Be sure to check timing while you are in there. If the arching continues, it will eat up the coil wire area also, if it hasn't already.
And use dielectric grease on the plug wires, but not inside the dizzy cap.

 

[alldodge]

arcing from the neck of the coil where the cap sits and across to both electrical terminals

Sounds like you need some new wires, and clean up the coil top. Get some good quality wires. You can use auto or marine so long as the wires are long enough. The differences are in the length and many auto wire seta are fine, but due to routing some come up short. Don't know what motor your working on, but you could take your old wires to the auto store and compare lengths

 

[Birdsboat]

Be sure to check timing while you are in there.

I have recently had the distributor and shaft removed, for removal of the inlet manifold. I haven't fine tuned the timing yet, I've just noticed this arcing when cranking over. I expect to have to advance or retard the dis cap to optimize the timing. Will the arcing possibly stop when the timing has been adjusted to optimum?

 

[Bondo]

Nope,..... Ohm meter the wires,....

Yer gonna find some bad ones,....

 

[gm280]

I say it is time to change the rotor, cap and all high voltage leads. Once you start getting arching, carbon tracks set up and you can't fix them. So some new parts should be on your agenda now. JMHO

 

[bruceb58]

Make sure you check the plugs and their gap. If plug gaps are too wide, this will also cause this issue.

 

[Birdsboat]

Ok this may be very stupid of me.....this arcing is happening when I'm cranking but I don't have the leads connected to the plugs because I'm waiting for new plugs to be delivered and I'm cranking the engine to check I'm getting fuel from the pump to the carb. Is the arcing happening because the plugs aren't connected??

 

[bruceb58]

Is the arcing happening because the plugs aren't connected??

LOL...yes!

Also very hard on your coil doing this. Pull your man overboard switch while doing this or ground the high tension lead.

The saturated coil has to release it's energy somewhere. It is just looking for the path of least resistance which is usually the plugs. The problem with doing what you are doing is the charge could blow through the membrane inside the coil between the secondary and the primary and ruin your coil.

 

[alldodge]

I just saw Paul Harvey

 

[Birdsboat]

Oops!! Thanks for the guidance that's more knowledge gained today. I have the motor out of the boat at the moment and set up on a pallet with a remote start switch set up for cranking. I will add another button to remove ignition power to the coil so when cranking there is no spark.
Thanks again

 

[harleyman1975]

Still not a bad idea to make sure ignition system is in good cond. ohm test wires and visually inspect at very least.

 

[Birdsboat]

Yeah I will do. What resistance values should I get for the wires?

 

[gm280]

Yeah I will do. What resistance values should I get for the wires?

That depends on the manufacture and type of wires you have. If they are simple stranded wire, then the resistance will be very low. In the range of 10 ohms or even less. But that also can be the meter itself induced readings If they are resistive wires, then the resistance can be pretty high. In the range of 1,000 to 25,000 ohms. Depending on the type of resistive wires and the length. So if you are testing your wires, look for extremely high resistance or even open wires.

 

[G_Hipster]

Was going to say 18k or so on suppression core wires. Seldom see non suppression wires as they emit RF and can interfere with electronics.

 

[gm280]

After rereading this thread, I can now easily see why you were getting arching. When there is no path for the high voltage to dissipate out, it builds 'til it gets so high that it arches over to the least resisted path. But that also pushes the limit of every part in the system to their max and can damage parts as well. Think high voltage in just the coil. The wire insulation can only hold so much voltage and then it burns through. And once it burns through it doesn't heal itseft again. And that starts the demise of the coil. JMHO

 

[G_Hipster]

yep, the spark will ground somewhere whether it be the coil or ecm and can possibly damage either.

 

[Birdsboat]

Ok, I have checked the resistance of all the ignition wires
Spark Plug Lead (Cylinder 1) 33" Long - 16.6Kohms
Spark Plug Lead (Cylinder 2) 33" Long - 16.2Kohms
Spark Plug Lead (Cylinder 3) 28" Long - 14Kohms
Spark Plug Lead (Cylinder 4) 28" Long - 13.8Kohms
Spark Plug Lead (Cylinder 5) 25" Long - 11.5Kohms
Spark Plug Lead (Cylinder 6) 25" Long - 12.2Kohms
Coil Lead 8" Long - 42Kohms

Do you think the resistance in the coil lead is too high? The resistance value is more than twice that of the longest spark plug lead even though its 1/4 its length??