Well I have a 1986 f250 hd with a 351w ho and it has a nasty low rpm skip to it. it has all new cap and rotor plugs and wires was running great its sat for about 2 days this morning I threw a yellow accel super stock coil on it (8140 I believe) and I just took it out and now I have a nasty off idle skipp to about 3500 rpm.now is it possable that the factory resistor wire is cutting the voltage to the coil to the point of week spark?? does this coil require and ballast or resistor?? the coil was on my 86 1500 Chevy with a 454 I had it wired to key on 12 volts no problems so I know the coils good I haven't rellay looked at it yet or put a volt meater on it just brain storming

 

I mentioned this before; at one of my local auto parts store, they have a bin of returned parts, and I see a lot of Accel Supercoils in there on a regular basis. So I'm thinking it's not a very reliable product.

Normally, the coil gets full 12v when you engage the starter for an extra kick of spark voltage when you're trying to start the engine. Then when you release the key from the start position, the coil gets powered through a ballast resistor, which drops the voltage to about 9v for normal operation. This means if you are constantly applying the full 12v to the coil, you increase the chance of overheating it, or burning it out.

Do you have another coil to try on the engine?

Also, you can try pulling/replacing the plug wires one cylinder at a time while the engine is idling to try to isolate the cylinder that's skipping.

 

I think its just a skipp across all 8 I have no other coils not even the old one right now key on engine off I ave 6 volts at the coil key in start I have 12v

 

You cannot just plug any coil into a Duraspark system. It HAS to be the correct coil for it to work properly. Chances are you've got the wrong coil for the system. Go look up the part number on Summit's website and see if that coil works with a Duraspark system.

 

Yep, the duraspark module is overloaded and drawing too much current, obtain the factory coil or factory replacement and the misfire should go away, the factory coil is just fine and works great 99% of the time..

 

The coil seems to be some what with in the specs of the factory coil guess ill try a factory coil monday hooe it don't sniw to much lol

 

I had this problem with my 77 Comet when I first got it running. I replaced the wrong (factory stock type) coil with the right MSD blaster coil. Been fine ever since.

 

Where exactly are the similarities ?
The primary resistance on the Accel coil is less than half as much as the stock coil, that equates to substantially more current draw on the module..

Primary Resistance
Accel - 0.200 ohms
Stock - 0.450 ohms - -

Secondary Resistance
Accel - 8.8K ohms
Stock - 5.5K ohms

Turns Ratio
Accel - 132:1
Stock - 85:1

 

To someone that thinks you can just toss in any old coil, those numbers are close enough !!