Hey guys,

I've supposedly heard that by gapping your spark plugs slightly wider, you can increase the horsepower of your motor, or the efficiency, IE: fuel economy, performance, smooth idle, etc.

I have the Accel high output ignition coil. Before everyone gets crazy, I've had it on for 40k miles, and it still works great, but I keep a spare too!

So, with that in mind, what is the benefit to having a shorter gap, or a taller spark plug gap?

Anyone have any experience or would like to add something to this?


Thanks,

 

a longer gap will allow more spark flame to ignite the mixture. However, coma, you don'y want to go too far, as you might actually break/weaken the center electrode from the plug.

 

Don't know about the center electrode... generally, a longer gap increases the amount of spark available to the mixture = cleaner burn = better emissions.

On the other side, a smaller gap = stronger spark (for forced induction and such) but less spark shown to the mixture.

Too small a gap might burn an electrode...

 

yeah, the longer gaps were used to help better burn the leaner mixtures on the old smogger cars, such as my 76 Bonnie & 77 T/A. gap was .060 if I remember right.

 

You sir, are correct.

'77 Firebird Esprit (354 Poncho) @ .060" gap.

 

Run a higher volt coil, AND run wires with very low resistence that will relieve the charge from the coil to the plugs without straining the coil (without causing heat buildup and weakening the volt output of the coil) and yes you will have a better, more complete burn resulting in more power.

A hotter coil and very good wires will allow you to open the plug gap for a larger ignition trigger without weakening the spark.

 

Everyone's always told me to cut the gap .001" for every 10whp you make over stock. Stock gap on LS1s was .060, I've dropped down to .050, most the guys I know running nitrous go down to about .040 or .035.

 

I don't know what stock is, but I set all mine down to .035", just to be sure that the spark will be strong enough to ignite the compressed mixture...

 

I had tried going to 0.050", didn't notice much improvement. Tried 0.055", car was sluggish off the line, and reeked of gasoline when it idled. This was all with the MSD 6AL box and Blaster SS coil, and changes were done back-to-back. (Good thing for gloves!)

I went back to 0.045, and never played with it again... this was, what, 3 years ago I guess?

 

Which wires?

 

My wires? MSD 8.5mm, universal HEI kit.

 

Damn, that was a HUGE increase, I wonder that the electrode didn't break

.005 should have been max, as you fond the car wold still run, and longer was just too long.