Looks like the RJ19LM
Plug PART NUMBER: 802592 $2.95 at Sear. should be cheaper at other places
on the back of the plug package it has : replaces CJ8, RCJ8, J19LM & RJ19LM. hope this helps.
The proper spark plug for 4hp Briggs & Stratton is a J8 which I use in all my motors.
what is the champion cross reference for a briggs and stratton spark plug 691043
0.030 is the gap for briggs and stratton 4.5 hp mower
.030
what plug size fits a 3.75 briggs and stratton,and a 19.5 briggs engine and what is the gap. thank you
official site for Briggs and Stratton Spark Plugs is: http://www.briggsandstratton.com/maint_repair/routine_maintenance/choosing_spark_plugs/ The proper spark plug will depend on the type of 6.5 HP motor that you have. Briggs and Stratton made several different ones and the best way to get the proper plug will be to call an authorized Briggs and Stratton repair shop with the mower make and model numbers.
.030
Rc12yc
Champion RJ19LM
Champion rj19lm