Crankshafts - Will They Interchange?
Topic: Will 50hp and 60hp crankshafts interchange? NO
The 50hp crankshafts have these features:
- Bottom wheel has a spline that is in a "blind hole" - it doesn't go all of the way through. That's why you need to use a "shorter" pump shaft when putting a 50 on top of a 60hp pump
- Connecting rods are "bottom guided" (left-right movement is controlled by washers on the lower crank pin/journal area
- Center seal is a "labrynth" type (aluminum disk with O-ring on outer perimeter)
The 60hp crankshafts have these features:
- Bottom wheel is splined all of the way through (open hole at top)
- Bottom wheel also has a groove machined inside for a seal - since the top is open this helps keep water out of the motor (and stops a potential air leak)
- Connecting rods are "top guided" (left-right movement is controlled by upper pin/piston)
- Center seal is standard elastic/spring type
The engine blocks have one main difference and that's the center bearing saddle. If you wanna use a labyrnth-type seal in a 60, you need to epoxy-up the hole/groove so that the O-ring has a smooth surface to seal against. A seal from a DT-85 works - especially if you keep blowing-up center seals. Contact John at Northern Crankshafts if you are having this problem.
Copyright 2011 - Capt'n Obveeus