1957 G model
Spark plug recommendation
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1957 G model
I recently bought a Servicar from a friends family who owned it since 1992. He's no longer with us to ask. HD recommends #3-4? Any good recommendations on spark plugs or a cross reference? It has Champion RJ12YC in it currently. Thanks guys.
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Re: 1957 G model
A Champion J12YC is the equivalent of a 3-4 HD plug, in fact they make them for H-D. But avoid the R prefix, that is a resistor plug for electronic ignitions and makes it harder on the system to fire consistently well. Do not use resistor plug wires either.
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Re: 1957 G model
Champion D14, D16, and NGK A9s are all 18 mm. A 57G with stock heads is 14mm plug size.
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Re: 1957 G model
A9 is not only the older & larger thread, but extremely cold and not suitable for street use.
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