cj14 i just picked one up for it today
Rj 19 lm
Champion 5861 or Autolite 458.
Rj19l
champion LM 19
This is a Tecumseh engine. According to the Tecumseh web site all small engines have a 0.030 gap
You may do serious damage to the lawnmower if the wrong spark plug is installed.
yes
Your owner's manual should explain that.
.030"
yes
Depending on what lawnmower you have just simply take the spark plug out and tilt lawnmoer
.030"