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Johnson 25 HP 1974 (25r74m)-CAM will not fit over crankshaft key. Testing before I start for 1 time

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doakholman

Member
I'm so close to having this engine rebuilt!!!

Need help with 2 more questions...

1) So I installed a new crankshaft key and the CAM will not fit over it. I've followed the directions in the manual by having the key parallel to the Crankshaft but the CAM will not fit over the key and I don't want to use a hammer on it. Thoughts?

2) Once I get the armature plate installed (points set), I only have the fly wheel and the rewind starter left to install! Any recommendations on how I should go about testing everything before I start the engine??? Then do's/don'ts on how to start it up for the first time??

Thank you again for all your help!!
 
If the cam slides down over the crankshaft "without" the key installed.... then the failure of the cam to slide down over the key is simply that the key is not seated properly... OR... the key is one purchased at a hardware store!

The key must be the proper key #120395.
 
Yes the CAM slid down the crankcase before the key went on. and I purchased the key from Marine Engine. So how did I install the key wrong?

— 120395 — KEY,CRANKSHAFT (1 required per assembly)
 
doakholman said:
I purchased the key from Marine Engine. So how did I install the key wrong? — 120395 — KEY,CRANKSHAFT (1 required per assembly)
Click to expand...

Sorry, I wouldn't know without actually being there.... a ever so slight tilt of the key? Some keys have what looks like a imperfection at one end (near the bottom), might look like a nick in the metal which provides a slightly tighter grab on the cam... if upside down, that would do it.

Yes, I know that most keys install either way but I've run into a few that work better when installed as above. It's a snug fit but it shouldn't be a bad problem.
 
The nick at one end of the key is there to provide a snug fit in the cam. It goes down. That snug fit may be what you are experiencing. It may require some light tapping (but don't break it)
 
I take a brass drift and tap the key fully into the seat so its straight with the taper and then tap on the bottom of the key until it is straight with the shaft your key is probably not fully seated. Possible a little chunk of crap in the groove, do not force the cam down they are very brittle.
 
I ended up taking the key out. Will order a new one. The key would fit into the slot on the cam as the key appeared wider than the cam. thanks for the help!
 
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