Spark Plug Mod

Hi, I have a Rock Solid Engines billet head on my 66cc, & with the squish clearance properly set at 0.030" the plug, if not shimmed with indexing shims or the side electrode cut shorter (to be just slightly longer than the center electrode & then side gapped) comes into contact with the piston crown, so yes, I have been side gapping plugs for over a year with no problem at all. When fitting a new plug I cut it down & then check the clearance to the piston crown by placing a ball of blu-tak on the crown, installing the plug & slowly cycling it thru a few cycles to make sure it has enough clearance. Cheers

interesting read.may try it.

I'm just about to try a plug one step hotter than I've been running, think I will give side gapping a try with the old NGK plug I pull out and see how it goes..... just gotta get past this rain and cold weather....

We use to do something like this years ago only we would grind a 45 degree angle on each side of the tip to make a point in the middle. That way the spark would go straight down when it fired

Hi again. To answer did I notice any gains from doing this, as I had to do as soon as I fitted the RSE head & set the squish clearance, I didnt have a base line sortta thing to compare to. I can tell u that I have absolutely no performance problems arising from a side gapped plug, it fires instantly when starting, even when I was using the RSE pull start I had fitted, tho that didnt last all that long with the stiff compression. I got sick of replacing broken cords. I have also tried cutting the faces of the center & side electrodes at an angle by cutting with a small cutoff wheel on a dremell. I found that a fine cutoff wheel would gap the plug at almost exactly 0.7mm if I did it carefully. I've done this on the last 2 plugs as I found it easiest to cut the side electrode enough that I could squash it down toalmost the height of the center electrode, then gap it in that manner, tho the angle is quite a bit more than 45# so that the spark is open to the chamber. Cheers

2door said:

Not trying to be a naysayer here but I've seen people experiment with all kinds of so-called performance enhancment modifications to spark plugs for years. The results are always inconclusive. I suspect the placebo effect has something to do with gain claims.

My question is if the 'side gapping' concept is good, why haven't the spark plug manufacturers adopted it? They spend a lot of money on R&D and if the idea was valid, why don't they do it? Doesn't it seem logical that if it works so well that they would change their basic design and improve their product?

Just asking.

Tom

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Well, I don't think any spark plug manufacturer had the likes of a HT motor in mind when they designed their spark plugs! We now these things aren't perfectly designed or manufactured, so if perhaps getting the spark more out front and center makes them run better more power to the side gappers!
I have no idea if there is any performance increase from doing this, but what the hay, I'm gonna give it a try with my old NGK before I toss it in the trash....

Edit: doesnt the 3 prong spark plug that comes with this kit kinda side gap a bit? I don't think any of the three prongs extend over the element like a reguar spark plug if I recall correctly?

I'd be inclined to agree wih 2door, really. I do it because I have to, or use intexing shims for clearance, I dont think it'd make any difference otherwise, not in these lo tech motors. With the stock head & BP6HS plug I had no problem starting or any misfiring so it was lighting off properly. If I didnt have to do this for clearance I'd be just throwing a B7HS in there as is, tho it doesnt take long & isnt hard to side gap if u wanted to try it. Ur not going to lose anything by trying it. Each to their own & experimenting is a good thing. Cheers