Couple more questions. I found a piece of plastic that looks like a seal of some sort between the lower piston/rod area and the center main bearing. The parts list that Frank posted shows a lower seal but this motor has no seal in that area. There is a cutout in the lower main bearing for a keyway. I will try to send some pictures.
Hi Dale,
There is no lower crankshaft seal below the crankshaft on the bottom of this engine. Like my ’54 SuperFastwin the bushing and the oil film do the sealing duties. It appears there is a place for a seal similar to what you found in your engine to seat between the crank throws inside the crankcase. There is what appears to be a seal bore on the lower side of the center main bearing. Presumably this is to prevent pressure pulses from escaping top to bottom inside the crankcase. What I don’t understand is how it could go in there unless it is not a continuous seal.
I believe that woodruff keyseat looking cutout in the crank at the lower main journal is what pushes the lube up the pipe that connects the upper main to the lower to keep the upper main bearing lubricated. Someone will correct me if I’m wrong.
-Ben
Correct, the keyway is a rotary valve for pumping the oil up to the upper bearing. If you look closely, you will see a couple of small holes in the bearing and the keyway joins those holes when the lower crankcase chamber has pressure and the upper chamber is partial vacuum.
EDIT: Actually, on that motor the two small holes I mentioned are slots milled in the case, one joining with the oil line.
Ok, I guess I’ll buy that story about that key way. Today I spent some time following the drilling that takes lube around that crankshaft area. Two different drillings end up in the upper reed valve area. There is two small holes in the lower main bearing. In and out I believe, small miracle if they don’t get plugged!
Do you guys think that seal by the center main bearing is necessary? Might get left out!
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