Motor is a 1993 Johnson 120 hp,,90degree motor. Timing is supposed to be 18btdc,,,well here is my dilemma..When checking it,I am getting a reading really high,and someone said that the motor will give a false reading until it warms up a bit,some kind of a cold start system.So I put the motor in a barrel,warmed it up for a few minutes,pulled the plugs,grounded plugs, unhooked the throttle cable,advanced throttle and timing cam the whole way,,and I get a reading of 24 degtees,which from what I have read would be a true 28 degrees when motor is smoking down the lake.I have run this motor approx 6-8 times with no meltdown,,,it runs good at top end,,runs a little rough idleing.The only thing that I did not do was use the tool to jump the spark 7/16 of a inch.Would this make that much difference,,,or am I missing something here.Any and all help appreciated.