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So pushing down on the throttle cam results in spark on both cylinders? Maybe excessive play in the mag plate or just a bad ground?
Bob
1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."Your spark returns to the mag plate thru the top of the brass retainer ring which is also a support bearing for the plate and also thru the center bearing which the plate rotates on. These areas must be free of any corrosion or buildup of any kind which can impede the electrical flow. Lightly sanding the inside of the plates bearing surface and other contact surfaces will help to ensure a good electron flow. Don’t bend or deform the brass plate.
To determine if the plate is too loose, try wiggling one edge of it up and down while holding the opposite edge still. A good fitting plate will hardly move at all while a loose one will flop around quite noticeably.
If it isn’t poor grounding causing the spark issue, I’d then suspect internal breaks or shorts in the plug wires or poor connections on the ends of them.
if it was me….
I would really clean up the whole oily looking mess of an engine……… certainly any part carrying electrical currents ..as suggested redo all connections from coil up to the boots clips… if need be install new boots with metallic wire crimped & folded back under the clips as suggested by mumbles
shine up.. polish all contact points and/or surfaces (retainer ring…… mag support plate coil grounds ( scrape all connection points and use star.. lock washers to bite into mating surfaces ) reinspect the mag plate plug wire routing
swap that lower coil/condenser/point kit to the top cyl position …we know it is good and never causes a problem
remeasure the coil secondaries for 4-7kohms from the boots to frame…. wiggle everything while measuring … see if it cuts out
reassemble the whole thing dry … no greases ..oil as a test … and keep that mag plate grounded as insurance
realign the coil edges on the mag plate
find a way to run that engine in the dark…3 a.m. if need be ………… look for arcing anywhere at high rpm when it fails
if all else fails make a nice trolling motor out of it !
..patience brings joy
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