Predator 420 with Autolite 3911 Sparkplug

[frostyflammable]

I have the Autolote 3911 sparkplug in all my 212 but this is the first 420 engine in my arsenal. I like the way the 3911 feels in the 212 but everywhere I look the 3910x is recommended. I don't like non gappable plugs and wanted to see if anyone has ran the Autolote 3911 in the 420 with positive results.

Thanks,
--Dan

 

[ezcome-ezgo]

To me a sparkplug is pretty much just a sparkplug. That said, I wouldn't want to be one.

 

[bob58o]

How much work did you do to the engine. The AR3910x is a cold plug, good for high compression. I milled my 420cc head 0.085" IIRC, used a thinner gasket and I think I ended up with a stock heat range plug. I started with AR3910X, then probably AR3911, then Back to stock IIRC. The AR3910x and AR3911 were both too cold for my liking. It has been a while though, I could be wrong. I'll look at what plug is in there next time I'm at my buddy's place.

 

[frostyflammable]

How much work did you do to the engine. The AR3910x is a cold plug, good for high compression. I milled my 420cc head 0.085" IIRC, used a thinner gasket and I think I ended up with a stock heat range plug. I started with AR3910X, then probably AR3911, then Back to stock IIRC. The AR3910x and AR3911 were both too cold for my liking. It has been a while though, I could be wrong. I'll look at what plug is in there next time I'm at my buddy's place.

Not much at all, removed the governor and put on the GoPower Sports stage 1 kit on there. Other than that, bone stock.

--Dan

 

[Joe-405]

I have never had any luck with those overly priced plugs in anything. And I've tried them in multiple items of mine from a stock 212 to a mild 420 on race gas.