Distributor/coil issue

[supertruck]

had a coil go bad a couple races ago and replaced it with a Blaster2 piece. running the Mel's ignition with the internal electronic unit. truck ran fine in both practices saturday and half the race. Motor started missing, like it was on a rev limiter, and would not pull at all. I pulled into the pits and looked under the hood. the plus and minus coil terminals were arcing to the center tower. coil was warm to the touch but not hot. also saw one arc from the cap/ wires to the intake. no other issues. any idea what to look at? seems unlikely that i got two bad Blasters in the space of a month. by the way, i did do some welding on the frame last week but the ignition was off although everything was connected.

[return to dirt]

it is actually arcing from the coil wire to the + and - terminals. need to check coil wire and plug wires, plugs, and rotor/cap for high resistance or too big of a gap. i never use those fancy coils, i just use ford e-coils.

olin

[drtlvr]

I agree. If the spark doesn't cross the gap of the plug, it will feed back through somewhere. Blaster coils (MSD) are made in China right? Take that off and use a factory coil.

[84Dave]

One other item to always consider on ignition systems. Your ignition in particular....... the electronic module inside the Mel's unit has a specific 'input impedance' value. He can likely tell you the value. Let's assume it's (2) ohms. If so, the primary resistance/impedance of any coil you use with the Mel's unit should be near (2) ohms also. If the primary coil winding resistance was, for instance, .5 ohms, the coil primary will flow/pull some serious over-current from the Mel's ignition module. Possibly to the point of module failure. Many a moon ago, I went through that 'dance' with a Pertronix module in the distributor & a very low MSD coil primary resistance. Race #2 on the new ignition system. In the pits, with the engine idling, a BIG cloud of blue smoke rolled out of the (4) vent holes I'd drilled in the distributor cap. Our race day was finished. Completely 'fried' the Pertronix module! Oh...... NEVER weld on a chassis with any part of the ignition system hooked up! Current traveling back through partially isolated grounds with burn up the modern electronics in ignition systems. That includes removing the distributor, before welding, if a electronic module is contained within! -Dave-

[supertruck]

as always guys thanks for the great info. as for the brand of coil, most of what i see says 6500 rpm max and i'm running 7500-7800. what brands are recommended, and what is an e-core coil anyway. don't know much about ignitions. Dave - thanks especially for the info on the Mel's module. I've seen coils with 1.5 and 3 ohms resistance so I guess it matter which one i use. never knew that.

[return to dirt]

supertruck, the ratings you are seeing is probably for a v8. a 4cyl only fires half as often per crank revolution so the coils will usually work at rpms higher then you will be turning. the ford e-coil is the stock coil found on engines that use a tfi setup. they usually have a handy mounting bracket and can be mounted in any position.

olin

[car62]

if anyone needs the E-coil with the mounting bracket,i have a TON of used ones that i will sell for $45 shipped priority mail to the lower 48 states.