So I need to tune up my 110 Johnson outboard. I have all the tools, the books, and the knowledge to do it. However, one tuning operation requires a test wheel be installed in place of the prop. Makes sense, since the engine will need to rev to 5000 RPM, and with a prop on it, the load would be too great while tied up.

I don't have a freakin test wheel! So my question is this: What is a test wheel? Can I get one? Should I get one? Is there any way around this issue?

Shoot  >

A "test wheel", at least as I remember them from fifty years ago, is used in place of the propellor. It doesn't move water like a regular propeller, but provides resistance when the motor is revved or tested while in gear.

Here's an image of some test wheels.

You don't need a test wheel, yea it makes life simpler but not necessary.

Take a partner to the lake with you. Leave the boat straped to the trailer and back into the lake until the anticav plate is about two inches above the water with the anticav plate trimed level with the water. Start motor and let it warm a few minutes an then go WOT watching the tac. If the rpm is below 5,100, pull the boat forward so the anticav plate it just a little higher in the water. If the rpm is above 5,500, back the boat in so the plate is a little deeper in the water. Once you get the rpm range right, have your partner do the gas while you check the timing.

A couple of suggestions doing this. Make sure there is plenty of clearance behind the boat, you will be throwing a hellava wall of water. Have the timing light and everything ready. Only hold the throttle wide open a few seconds, just long enough to get a good reading, then back it off, make your timing adjustment and check it again. Also, I would recommend doing this with a spare prop if you have one. This can suck sand and small rocks off the bottom and put small knicks in the leading edge of the prop. While not creating a big problem, this is something you might not want to to do a high dollar stainless prop.

Forgot one suggestion, take a nerve pill.  Until you've been looking over an outboard screaming at 5,500 rpm, you don't know just how un-nerving it can be.