Originally Posted By Cab_Burge
You had the same experience that a lot of racers and hot rodders have, they don't hear it until the motor quits or starts smoking whiney
I learned to look at the plugs frequently until I knew the tune up was safe up
On my stock 415 HP M.W. on the old 100+ octane high lead pump fuel in 1971 to 1973, it liked the stock J11Y, not the J10y or the hotter J12Y spark plugs. I could hear the difference in idling right away, I could see the differences in on the plugs with one full WOT blast down the street work
As far as heat on the plug tip the center porclyn determines what the tip temperature will be, retracted or projected shruggy
More porclyn around the center electrode less heat transfer work
Plug electrode heat build up transfers through the porcelain to the plug main body. The farther it is from the main body, the less heat transfer there will be and the hotter the electrode will run. What I was always taught. By 73 high lead content fuel was being phased out as it was killimg convertors - and us of course. Attached is a comparison of 3 plugs that I have run in the past in my SB. Right 2 are NGK's. Left is a Champ. Right plug is by far the coldest (-9) which I run in my blower motor. Left 2 I have run in NA motors and they would not survive in my blower motor. All worked well in the proper environment.

plug compare.jpg
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