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Does anyone have any experience with Autolite Racing X plugs?
I bought a set off of Ebay that were supposed to be Autolite Racing AR 3932.
When I got them they were Autolite 3932X plugs. They have a X shaped tip on them
that I have never seen before.A search turned up nothing.
Any info at all would be greatly appreciated.
Thanks,
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Sorry Ron,

I'm not familiar with your spark plugs, but I can provide a quickie over-view of spark plug design.

In the world of serious spark plug design (as opposed to gimmicks like split fire spark plugs) there are two criteria engineers seek to achive. One is to reduce or eliminate the shielding of the spark from the fuel air mixture, and the other is to keep the sharp edges of the center electrode sharp.

The spark, or current, jumps from the sharp edges of the center electrode to the side electrode. Each time the spark jumps the gap, a molecule of metal jumps the gap too. This is why the center electrodes slowly become rounded. The molecules of metal can accumulate on the side electrode, forming a whisker or stalactite that hangs from the side electrode and can bridge the spark plug gap and cause the plug to fail. A strong spark requires a sharp edge on the center electrode, so engineers strive to design plugs that will stay sharp, the small needle like point of a Platinum electrode plug exemplifies such a design.

In a move to reduce the shielding of the spark from the fuel air mixture, some plug designs have extended the center electrode so that it is flush with the side electrodes(see the attached picture below). This exposes the spark to the fuel air mixture better than the familiar conventional side electrode design. It emulates a spark plug design developed in the '60s called a surface gap spark plug, which for some reason never caught on with automobiles or motorcycles, although I think it is used in the aircraft industry.

Most racers have heard of teams "indexing" their spark plugs. This is another method of avoiding shielding of the spark from the air fuel mixture. The idea is to use a plug in each cylinder that will be oriented, when tightened in the spark plug hole, so that the side elctrode does not sheild the spark from the fuel air mixture in the center of the combustion chamber.

The unique design of your spark plugs probably addresses one or both of these condsiderations.

cowboy from hell

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Last edited by George P
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