1974 Johnson 40 HP Outboard Motors Service manual, Page 35Get this manual
Before installing the plug, be sure the plug seat in the cylinder head is clean and free from obstructionsSee Figure 4-1 9Screw the plug in by hand, then tighten to the specified 17-12 to 20 -12 foot-pounds If threads are stripped in cylinder head, HeliCoil
inser ts are available Caution hould be taken when installing the Heli-Coil insertsTools for inserts are available from your parts distributor
bDirt, foreign particles, and oil are very detrimental to contact performanceThe oils and acids from person's hand, even though clean, can affect contact resistance Oil deposits on the points will cause them to burn out after very short period of operationIf points need leaning, use alcohol or trichlorethyleneNEVER FILE POINTS - replace themcTo remove any traces of dirt from contacts, in sert strip of bias tape and work it up and down be tween the pointsRepeat entire cleaning procedure for second set of pointsdCheck points lor good electrical contact, using ignition analyzer as described Wlder "Breaker Point Testing,Check and adjust breaker point setting as necessary as described under "Breaker Point Adj ustment