Side Gap Plugs

[TADracer]

I got into a tinkering phase awhile back and tried something I used to do when I raced Super Stock a long time ago before the high-power ignitions of today were available (back when your handicap was the national record and not a class index). Alot of us used to side gap spark plugs to get a fatter spark from our weaker coils, kind of like what the expensive platinum and iridium plugs claim.

So I took a dremmel and cut back the ground strap from an old set of plugs and tried them out. You could actually tell the difference. performance seemed a bit more crisp.

Pic is not very clear but you get the idea.



The thinking is that since the spark generates more from a sharp edge, a coil will start and continue the spark more easily (from the center of the firing tip to the corner of the ground strap). And since the ground strap is moved back it makes the spark grow into a fat curve instead of just a spark between the two pieces of metal. Also, since the spark is now unshrouded it lights off the fuel/air mixture quicker.

Down side is that your plugs might only make it for about 8,000 miles or so instead of the usuall 10,000 I get. Still, it is a fun tinker to try and it might be worth an extra HP or two.

[bikerphil]

Yep, I run 'em that way too. I also notice an overall improvement. I have mine angle gapped at about .020" with XJ 3 ohm coils and .030" with my 3 ohm Accel Supercoils. Good tip Mike.

[XS1100 Newbie]

Wow! I had not remembered that. We used to also file the tip of the ground to a point, but it ate it up fairly quick. Thanks for the reminder, out to the bike i go.

[WMarshy]

I may try this with a used set... not sure I want to do this to a new set. Can you explain the gap measurement you are trying to achieve and how to measure it?

[bikerphil]

I may try this with a used set... not sure I want to do this to a new set. Can you explain the gap measurement you are trying to achieve and how to measure it?

http://performanceunlimited.com/docu...degapping.html

[davidsymons53]

Good tip. I'll try it.

David

[cywelchjr]

Plugs are cheap, I may pick up a set of NGKs and set them up side gapped and pop them in and see how it runs. Of course I'm thinking I'm going to pull my coils and check for cracks, I suspect I have a crack in one like cbug does, but I think I'll use high temp RTV if I do rather than JBWeld (I'm sure the JBWeld would work, but the RTV would be more flexible I'm thinking and just as durable in the particular use).

But I'm not do for a plug change for a while yet, but may do it anyways for the group ride I've got coming up next month and see how it runs.

[petejw]

we did the same thing back in the 80's and
id forgotten about it til bikerphil posted the tip
a little while back.
i also index the plugs, works well.

[Ken Talbot]

Very nice! This one definitely deserves a place in the tech tips section.

[rman]

i also index the plugs, works well.

What is that?????

[petejw]

What is that?????

indexing the plug is lining up the gap of the spark plug
so its facing the combustion chamber,
pretty much looking at the plug in the engine in situ , the
earth strap would be facing at 6'oclock.

[81xsproject]

Don't you have to use shim washers to achieve that?

[petejw]

Don't you have to use shim washers to achieve that?

u can do,
or u can just buy a few extra plugs and try
different fitments which i do.

[TADracer]

I may try this with a used set...

I would try it on a used set first instead of dicing up a new set pf plugs.

I tried it with a .025" gap set with a feeler gauge at an agle between the tip and the strap. After you run them for a good ride you can see a little line in the firing tip where the spark generates. That is probably where the plug will erode the fastest.

[natemoen]

Had some old plugs to play with. First plug, hit the electrode. Second plug seemed to work ok. Third plug dropped on the strap. Gave up after that.