j6c vs j11c

[elgin2]

I`m working on a RD-19 that calls for j6j aka j6c plugs. Took the plugs out and found it had j11c plugs in it. What is the difference in the two series plugs? What would the reasoning be for changing to a different plug? Thanx,Mike.

[frankr]

The J11C is way hotter, and have no business being in there. You may already know this, but "hot" vs "cold" in spark plugs refers to the temperature the tip of the plug when the engine is running, NOT to the temperature of the spark. The goal is to be hot enough to burn off deposits of combustion, but not hot enough to cause it to ignite the fuel charge before the spark happens. That condition is called pre-ignition and can cause severe engine damage.

[elgin2]

Thanks Frank. I`m working on this for a friend of a friend. He bought this 15 yrs ago supposedly restored. They started it for him to prove it ran and then drained the carb. Been sitting ever since. From what I`m finding out he bought a old motor with new paint and new fuel lines. At least it doesn’t smell of old fuel. I`ve installed a impeller and new lower unit fluid. Found the vent plug with silicone around it and the fill plug with 2 gaskets on it.

[optsyeagle]

I’ve met many people who think that all spark plugs are the same, since all their needed for is a spark. The only difference they see is the size of the hole they screw into. If it fits, it gets used.

[dave-bernard]

Whiat til they put a long reach plug in a short reach motor . bingo bango.

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