1978 Johnson 55 rough runningproblem solved

" I was checking the top dead

" I was checking the top dead center of the #1 piston and I noticed the timing read 16* at the timing pointer with the piston at TDC. I removed the flywheel and found the woodruff key had split. Replaced woodruff key for .35 and it now runs and idles like a charm.
I drained the lower unit, Hey! no water in the oil. Lake Monroe here I come!
Thanks to everyone for all the good information. "

"Bryan.... Unless you picked u

"Bryan.... Unless you picked up a new looking but used flywheel key, you have the wrong flywheel key which may not hold up under power. A new flywheel key for that engine does not sell for .35, more likely something like $2.75 or so.

The OMC part number is 307480. Note that the key must be installed with the straight edge of it being vertical with the engine, not in line with the crankshaft taper.... and the flywheel nut must be torqued to 105 foot pounds.

If not torqued properly, that key will shear again (guaranteed), causing damage to both the flywheel and crankshaft tapers.

Joe "

" Yikes! Joe, I went down to A

" Yikes! Joe, I went down to Ace Hardware which is about 1/2 mile from the house, took both pieces of the old key with me, carefully matched it up with a "Hardened Steel" key. I believe it was 5/32" x ??, physically matched perfectly. I took some 220 sandpaper and knocked the surface rust off of the crank snout and the inside of the flywheel taper, installed the key on crankslot with a slight tap of a hammer, fit was snug, not tight in the key slot, slid the flywheel on, tapped it down just enough get the nut started, about 3/8", and torqued it down with a 1/2" breaker bar and a 24" prybar to hold the flywheel, to well...the bow started coming around. I do own a torque wrench, I will double check the torque tommorrow, I would hate for my wife to have to paddle that pontoon boat all the way back to shore.
The key seemed like a perfect fit, had the same dimensions as the old one, the material may not be the same as OMC. I thought about that before I installed it, I figured if I had two clean surfaces and enough torque the friction of the fit would help hold the flywheel in addition to the key. "

"Bryan.... Hopefully you got l

"Bryan.... Hopefully you got lucky on the flywheel key and that item will work out fine. Torquing the nut and a test run will tell the tale.

Joe"