Stevens instrument Company sells the ones reccomended by Evinrude. I believe its the S-94 or something. I would bet that you could buy one on this website and help support the forums.
Staple a couple of pieces of wire on a piece of plywood.-------Set up a gap of 7/16" between the ends.-----Stick one end on the block with an aligator clap and the other end into a plug wire.
ok got the open air gap tester from parts store..and hooked up to 1st plug wire and clipped to motor block,now what should be going on with the other 3 plug wires ? just hang there? (I have all 4 plugs taken out)
Pull out plugs. Disconnect the plug wires from them. Then ground out three plug wires and check the spark on the remaining one. Do the same to the remaining other three. OR !! Leave the plugs in and pull the wires off so motor doesn't start. Then check the spark on each wire one at a time.