Lower Unit Compatibility

[joepcdr]

I've got a 40 HP 63 Johnson with manual shift and a 40 HP 67 Evinrude with Electric shift. The lower units on both these motors are in decent shape. The problem that I got is both motors have sheered their flywheel pins several times over the years gouging up the shaft to the point they won't hold a pin anymore. So last summer I made several calls to all the machine shops and engine rebuilders in my area to see if I could find anybody who would be willing to weld the gouges and turn the crank back to specs. Everybody I spoke with said they would do it, if it wasn't for the shaft having that taper on it. I'm not a machinist so I don't know what having a taper on the shaft has to do with anything. Anyway I've called around all over my state and have come up empty handed so far.

So I get on craigslist and look around on ebay to see if I can just find the crank shaft. What I'm finding is it's cheaper to get a used powerhead than it is just to get the crankshaft itself. Which doesn't make sense to me! But it is what it is! So my question is if I happen to find what appears to be a decent power head. How far up the model year chain can I go that the lower units would be compatible with.

 

[racerone]

FACTS-----You can only use a factory key.-----Hardware store items are NOT the same.---------The key locates the flywheel for proper timing of spark.-----The flywheel is driven by the locking tapers when properly torqued to 100 FT LBS.----See if you can now use valve grinding compound to lap the tapers for a proper fit.-------And no I would not do any welding on a shaft like that !-----Powerheads up to 1970 will interchange.-----Your location does matter in finding the parts.---Plentiful in some areas.

 

[joepcdr]

These pins where sheered before I got the motors sometime in their past lives. The one I had actually out on the lake several times before the flywheel spun. When I got things apart I found that they "fixed" it with JB Weld. After I found that out I picked out all the JB Weld to see how bad and deep the gouges are in the motor that was running. I was shocked it ran at all. There wasn't enough meat to really hold the pin in place to begin with. The gouges are pretty nasty in both cranks. I do have a local boat shop I can get parts from. But he's pretty proud of his products and its cheaper for me to order online by a lot. Thanks for the info on the interchange. That at least gives me something to look for. Even if that means I find a engine with low compression that I have to re-ring.

 

[racerone]

I have many parts / powerheads but I believe you will be too far away to walk over.

 

[joepcdr]

Since I'm from Kansas you might be a bit of a jog. LOL

 

[racerone]

Yup, too far away.

 

[joepcdr]

I think I'm just going to have to look for a couple of donor motors or source slightly used ones off of ebay. Found a company in Maryland this morning that claimed they could do the work. Shot them an email for a quote and they came back with $400.

 

[flyingscott]

You could probably buy 2 good donor motors for that price.

 

[racerone]

Or 3 or 4 of them.-----All about location.

 

[oldboat1]

I agree with the above suggestions. If it were me, though, I think I would play with it a little just for grins. You might try a few hardware store keys on the off chance that one of the "almost right" sizes might work in the damaged slot (maybe slightly oversized key). If so, clean the taper and torque the flywheel to spec. If you get the wheel torqued down tight, there's a chance.

The flat edge of the key is supposed to match the angle of the flywheel slot, btw, not the tapered shaft. But it's the flywheel fit and torque that counts to keep from shearing keys. Also, if the flywheels interchange, you might try that to see if you can get one of the motors to work.

I think the danger is that you might shear a key(!) and ruin the taper -- but gather that's not an issue now.

If you do get a fix, it could let you down. That's not so great if you're on big water, but not a huge issue if on a smaller lake. (Good chance to add a get-me-home motor.)

 

[racerone]

The problem is not the width of the key.----It is the amount that the key sticks out from the crank.----The key locates the flywheel.----The clean proper fitted tapers drive the flywheel.

 

[oldboat1]

You could operate the engine without a key if you can center the flywheel exactly over the shaft slot, and fully torque it in place -- assumes the proper taper is still intact. You might initially tap the flywheel in place over the taper, then torque the nut.

 

[kbait]

As stated above^, the flywheel isn't driven by the key, but the tapered shaft/flywheel bonded by torquing the flywheel nut..the key simply locates the flywheel (and magnet). Mark or scribe the exact center of keyway/key onto flywheel/shaft stub respectively, insert correct key into what's left of the keyway and try torquing it down. If your scribe marks align, magnet/coil timing should be very close, and the taper-fit won't budge if torqued to spec (105 ft/lbs). I would definitely try it before swapping cranks.

 

[joepcdr]

That's a interesting thought. On good note I did get one of the motors running. It was the johnson that was having shifting problems on me a couple years back. Turns out the shift lock mechanism isn't moving like its supposed to be. I pushed it over manually and was able to get the motor to fire up and shift between the gears fine. Problem is to fix it right I'm thinking I'm going to have to pop that flywheel off again. Something in there is binding up, preventing it from moving like it should. Now of course, if I'm careful. I probably could just zip tie it back and run it as is.

 

[F_R]

Post a free want ad on the classified ads forum at www.aomci.org Somebody over there will have a good crank for you. Possibly a flywheel too.