Wow BA...that's huge, unless you have an HEI ignition. 40kV won't really support much more than .045" very well. It'll probably run, but it'll be taking every bit of that 40kV to fire all of the plugs, leaving very little overhead in case a wire starts to go bad, or a terminal in the cap burns up.

You don't really see plug gaps that large until you get into newer, high voltage ignition systems. An HEI system puts out 100+kV and has plenty of voltage to fire across that gap.

 

not to hijack but i have a question,

a more powerful coil helps...what? and whats the advantages of opening the plug gap?

 

I left the resistor in place which never gave me a problem. But then for the sake of it I just added a 0-resitor cable to the thing. you know those plastic clips that hook into two cables at a time. so i ran a normal wire the full length of theb resistor wire that hooks into the resistor wire at start and finish. this way i can easily remove my addition.

But I'll completelt remove the pink wire for my new project now and run a new cable to the box.

Kalli

 

The coil supplies voltage to the spark plugs. The more voltage you have at the plug, the easier it is for a spark to jump across a given gap. The longer the spark front, the more fuel you ignite, giving you a better burn.

The stock gap is .035, which works fine with the stock coil, which probably puts out ~15kV. If you can up the gap to .040 or .050 by increasing coil voltage, you get slightly more fuel ignited in the chamber, improving combustion efficiency.

You want some overhead to work with as well, though. Just because you have a 40kV coil doesn't mean you want to use all 40kV every time you fire a plug. If you do that, you don't leave anything left over for other problems in the system. As the ignition system wears, plug gaps get wider, plug wire resistance increases, and gaps between the cap and rotor terminals increase, all resulting in higher resistance. There's also an increase in resistance when you increase dynamic compression during acceleration. Higher resistance means you need more voltage to jump a spark across the plug gap, which is where that overhead comes in. I haven't shoved my car on an ignition scope recently so my memory is a little fuzzy, but I want to say my system took about 8kV under no load, jumping up to something like 14kV during snap-throttle.