I have an old scott-atwater 3.6 hp. It sat in grandfather-in-laws cottage basement for 30 years and was never used. Serial# 30554959 ; I am assuming it is a 1954? Model#189 with Q7 under the model#.I took the sparkplug out last summer cause I had no spark. Got busy and had to leave that project until now. Now I can't find the plug or the gap. Turns out step-father had one of these motors in the garage. Called mom, she said it has a champion plug #J17LM in it. Is this the correct plug and does anyone know the proper gap? Thanks in advance for your time and info.