Im runnin autolite 23's with the 6A, 8.5 wires and MSD coil. What gap do you all recomend with the spark box?

 

Whatever stock is?

 

i agree, stock is more than fine. if the engine is N/A then you could go a little bigger, but you wont see any performance gains and will most likely burn up the ground strap quicker.

 

how the performance with that box, i been really considering getting one. i heard the 5.9 falls flat on its face at high rpm and that the 6a box helps.

 

Haven't really noticed too much in high end. I know the box is geared toward the lower end of the RPM range, due to that too high, the box stop creating multiple spark, I think around 3500.

All my gearhead buddies tell me It's a good way to completely burn your fuel @ higher altitudes.

 

Well, MSD's F.A.Q.'s page said I can run up to .015 larger gap. Will a larger gap help performance? Or just burn up my plugs faster?

 

a larger gap will create a physically larger spark flame. this could help burn some unburnt fuel, but i would assume the engine A/F ratios are close enough that this shouldnt be a problem.
my concern is that the larger gap requires more amps to jump to the ground strap. this results in much higher temperatures and couild end up prematurly destroying your sparkplugs. another concern is the higher temp could create a hot spot on your plug and lead to detonation.

 

you're going to have to experiment. I run .045 with the box as that's where mine runs smoothest. You're may differ. I'd start at .040 put a 100 miles on it, go to .042 and put another 100 on it, etc., etc.

The Box will let you run a bigger gap, and it's up to you how long you want to go before changes. With the box, your plugs rotor and cap contacts are all going to get tapped 3 times during one firing sequence under 3000RPM's. Those extra taps wear parts quick. My cap and rotor is usually done at about 25,000 miles. You can fel a noticeably rougher idle. That's when I need to swap it out and replace it, and I always did plugs at the same time. I'm actually running the NGK Iridiums right now and they seem to be holding up well. I pull them every now and again to check the wear and spark gap.

 

Thanks guys, I jumped up to .042 now and I definatly notice a smoother idle. I think i'll run that for a few trips to the hills.

 

The factory gap spec on my truck is .045.