FObangah

I recently over heard a couple of guys talking at the auto parts store about "Side gapping" their spark plugs for better gas mileage. I've heard of it before at the track but didn't think much of using it in a daily application until I realized it was time for new plugs in the ol' chick car. Here's a link for those that havn't heard of this before:www.nakedpicsofYOURmom.com/I'myourREALdad

I was wondering if anyone here has had experience with using side gapped plugs, no matter the application, and what sort of "gains" you've seen from doing this. Details please!




MODS:
I was up in the air about posting in Auto. Discussion but figured since I'd be trying this today or tomorrow that it " Technically " belonged in Tech Talk for on lookers.

HatefulMechanic

Seems to me that will cause accelerated wear, especially since you are moving the arc point from a (relatively) large area on the end of the electrode to a very small and narrow edge, which will inherently wear quickly and increase the gap.

I'd say you would have better luck with indexing your plugs, but to be honest even most racers don't even do that anymore.

FObangah

My focus would be more on fuel economy as opposed to power (which kinda go hand in hand) and with autolites going for a little over a buck a piece, wear really isn't an issue if I can see big enough gains in the MPG department. At $3 a gallon, if I save 1 gallon of gas over the entire life of the plugs I've just about made my money back on them. I'd imagine over a span of say 20,000 miles, I'd see enough of a gain to warrant giving this a try no?

I thought about what the posted article says about the increased wear and thought maybe dropping the gap from .042 to .038 may make up the difference while still "arching" the spark out in to the fuel/air mixture. Thoughts?

I've considered the drilling method as well, but I don't keep tiny cobalt/carbide bit's laying around, where-as I do have small files and a DREMEL handy.

Fabrik8

I don't really believe too much in DIY spark plug mods, mostly because there isn't any good way to test or prove anything on the street, and any small gains on the dyno can often be masked by the fact that the modified plugs are fresh, not that they are modified. I actually got into a discussion about something like this with the spark plug designer (actually a combustion engineer) I used to work with, and she was confident that there were all kinds of things that could be improved if you're dealing with 60 year old V8 combustion chamber design and that a lot of "spark plug improvements" were actually due to the use of an aftermarket ignition coil instead of the plug itself.
I'm just not a big believer in mods like that without testing to prove it, and someone saying "Racers have been doing it for decades, and the spark plug companies don't want you to know about it". Anytime there's a conspiracy involved where a company doesn't want to make their product with such a great performance improvement, my skepticism meter maxes out.

burnoutboy

Just index em, th only tool required besides a socket wrench is a sharpie.

Any gains seen from side gapping will likely be so minimal it's not worth the effort. I'm with Fabrik8, if it produced a better result we'd see new spark plugs coming side gapped.

FObangah

I was thinking along the same lines but attempting it with the old plugs first and seeing if I notice a difference. Even with that, I suppose the re-gapping and the fact that cutting the "head" off of the outer electrode would pretty much do away with all build up, meaning it wouldn't make much difference than taking out existing plugs and cleaning them, checking gap, and re-installing.

FObangah

There are plugs sold like this, I believe it's an NGK plug. The electrode comes out of the threads at a 45 degree angle and just barely lines up with the side of the inner electrode. I'm searching for them now.

EDIT: Here they are-

Fabrik8

Yes, there are plugs like that, but the entire plug is designed around that concept, including the core nose and the core nose height, and the electrode, and the strap, and everything else. It's not just a matter of modifying some existing J-gap plug to work differently.

I'm also not a big believer in indexing plugs in a modern pentroof chamber design.

burnoutboy

Are you saying not a big believer as in you don't think it really helps flame propogation because of swirl or what?

FObangah

Now that I think about it, those (pictured) are actually designed for high compression motors where clearance is an issue. They just so happen to look like what a side gapped plug does.

You're probably right about indexing in a modern pentroof chamber (hemi as well) because the plug sits farther back inside the head in comparison to say...a wedge engine, where the fuel mixture blows right acros the head of the plug. This would lead me to believe though that the pentroof (quenched or un-quenched/ squish or no squish what ever you prefer to say) would be the best candidate to actually see a gain from a side gapped plug. Help me out here if I'm omitting something, it's probably because of ignorance as opposed to trying to sound smart.