need help with plug wires

[dougsoldcars]

When setting the timing on my 408 stroker I heard what sounded like sparks going to ground. Tonight in the dark my concerns were confirmed. I have sparks from the plug boots to ground and arcing between some plug wires near the distributor and actually saw both the positive and negative pole of the coil dimly lit.

I have an MSD distributor, MSD Blaster coils and MSD wires. Seems to me the wires are a problem. I have a set of 8mm Taylor SST shielded High temp wires for one of my 350 Chevies. I wonder if I should try these.

Has anyone had success with a particular brand and diameter plug wire in this application?

Thanks for your help.
Doug

[coupe32]

I run a MSD ignition and a blaster coil and use Accel 10.8mm spiral wound wires with no problems. As long as the wires are spiral wound and have good insulation I think they should be okay.

[440roadrunner]

Sparking to ground like that almost ALWAYS indicates an open somewhere.

Imagine if you unhook just one spark plug. UNLIKE unplugging something from an electrical outlet--which maintains stable line voltage--the coil is "unloaded" by the unhooked wire (in this example) The unloaded plug tower now SOARS to a very high voltage, and this voltage starts looking for an easy path to ground--just like lightning.

I would get an ohmeter and check out all wires including the coil wire, and "shake" them when connected to the meter to look for big swings in resistance.

Also suspect stuff like a damaged rotor. There is a possibility you have some strange situation. There's been some discussion about "rotor phasing"

What this means is that something causes the points or pickup coil to trigger the coil when the rotor is NOT lined up with the cap tower contacts.

This in effect causes a huge spark gap inside the rotor--to plug tower area, and again, the coil voltage is way high, looking for a path.

Broken spark plugs can also cause this problem, as will ANYTHING that causes an open in the circuit path, all the way from the coil tower--to the cap--to the plugs.

[mhenesian]

Hi dougsoldcars,

Make sure the spark plugs are tight ! Sounds stupid, however, a loose plug will not "ground" the anode (the curved electrode), so the volts will build up to the limit of the ignition box (> 60 kV), causing the problems you mentioned. Plugs loosen up with time and get oil/fuel on the threads.

440roadrunner's explanation above is very accurate. He just forgot to mention the obvious problem. Also, its not a good idea to crank the motor with the ignition wire removed from the coil tower, or even disconnected from the distributor cap. You'll get arcing from the coil tower to the (+) or (-) connections and possible arcing between the connections. I've done it an I'm sure I reduced the lifetime of my new MSD Digital 6 boxes,

Mark

[cudabob496]

Also, be careful, a kid in my neighborhood was working on his engine and the coil went to ground through him. He was hospitalized, then the next day he died from heart damage due to the current that went through his body.