Should I use resistor or non resistor Autolite AR3910X spark plugs on a predator 212cc

That is the plug that Melvin at Dover recommended. I’ve been using them for 2 years in box stock predators with purple restrictor plates.
 
Back to your original question I have always ran resistor plugs. Many years ago I sold NGK spark plugs and their representative got me free plugs. He told me to run resistors and I dont remember exactly why but I always have, and seriously doubt whether they ever hindered any of my engines whether circle track car engines or kart motors.
 
That is the plug that Melvin at Dover recommended. I’ve been using them for 2 years in box stock predators with purple restrictor plates.
Im unrestricted im the 15 and up Stock Predator 212cc class at Jackson Speedway, Owosso Speedway, and Arthur Raceway in Michigan
 
We raced flathead. Then clones. And now, we have almost come to a crawl.

The Predators!!!

They are in the shop. We are going to use a Champion Spark Plug in these engines.
 
Just use the 3910X and live with it occasionally fouling if you sit and idle too long. Consider that when you grab the starter on the grid.
The 3910X is used because it displaces CCs in the combustion chamber (which is measured without the plug as a consideration.) It is beneficial within the rules to use this longer reach, wider base (4 prong,) plug in spec classes like we have (Predator, clone, L206, etc.)
Is it the best plug for the engine? Absolutely not, but given the rule set we use, it consistently makes the best power.

Don't even get me started on proper English, grammar, spelling, and punctuation. I've got a college degree and am still terrible at writing!



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Many understand that the Autolite AR3910X is actually to cold for most stock class applications.

Years ago when I first heard about the Autolite X PLUGS I immediately consulted a heat range chart. The plug is actually available in three different heat ranges. In addition to the 3910 there is an AR3922X, and a AR3933X there was a very limited production AR3911x but I don't think you will ever see one. I have always thought it was laughable that so many promoted the 3910X and apparently never bothered to consult a heat range chart, even Briggs and Stratton failed to do so when writing the rules for the LO206. Tired of fouling out this plug? Try the hotter ones. They are readily available. I have been using all three for a very long time.
 
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