Re: More 135 Johnson problems

[Don]

Well, kind of hard to say, could be just about anything. Are you sure it is running on 4 cylinders? What pitch prop are you using? Those engines were not the smoothest idling engines, but it should at least stay running. Like others have said, that hole in the gasket is for newer engines with the primer port on top of the carb, and is the correct gasket for your engine.
I know you have checked the sync a few times, but are you sure the timer base is moving smoothly in both directions? I had an interesting case, that I wasted many hours on years ago, all because I overlooked the basics. The old 115hp like yours was mounted too low on the boat, which kicked up considerable rooster tail spray, that ended up being ingested through the lower pan. I had wondered why such a nice looking trailered boat could look so rusted under the hood! In any event, the engine would run fine when at idle and when accelerated to WOT, the problem occurred when you backed off on the throttle, the engine would sneeze/fart stall out every time. I thought I had check most everything, finally theorizing (grasping at straws) that the pack was misfiring, needless to say the new pack changed nothing. Finally, by accident, I discovered the problem while rechecking the sync. The constant salt water bath had stiffened up the vertical throttle linkage pieces. So, the engine ran fine while accelerating. But, during deceleration, the stiff linkage would retard the timing completely before starting to close the carb butterflies, causing the lean spit stall situation. Normally, the carb butterflies start to close first while the timing is still advanced on these engines.
So, be sure the sync is right and that throttle mechanism is working correctly. The only other relatively simple thing I can think of is a sheared flywheel key, which will cause erratic timing that wont show up on a timing light. I thought of retarded timing only because you mention it won’t idle and is real slow to accelerate, which sounds like retarded timing. It is easy to check for a sheared key with the OMC TDC tool, but am guessing you don’t have that. Are you sure you retorqued that flywheel correctly, to 105 foot pounds?