Champion rc12yc, Briggs 491055 or Champion Premium plug (platinum) #3071
GAP .030"
no
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Rc12yc
A champion RC12YC spark plug is 14mm thread diameter. The torque for this size is 18-22 foot-pounds (25 to 30Neuton·meters)
The RC14YC in a hotter plug.
yes
I"ve been trying to find an answer to this question myself and belive the Autolite 3924 corresponds to the Champion RC12YC.24-7423 - Champion RC12YC Spark PlugRC12YC Champion Replaces Autolite 3924, NGK BCPR6ES..
RC12YC in Champion
champion RC12YC of ngk BKR5E-11
.035"