Test wheel for '86 Johnson 120 V4-newbie

[USCGCPOMK]

Greetings, I am new to the forum and just getting started in the whole interweb forum stuff. Please forgive me if I seem un-educated. I recently acquired a 1986 Hydra Sports 1800CC with a 120 V4 on the back. It was abandoned in a filed for a few years but the hull is solid, aside from about 20hours of compounding I did to remove the oxidation. The engine I got running, compression is about 90 on all 4 holes. I know there were a few "mechanics" that worked on the boat before I adopted it so I'm not sure what they messed with. I am going to set everything to factory and do a throttle sync this weekend. I have searched everywhere to find a test wheel for this boat and came up with P/N 386246. Unfortunately these are nonexistent for sale anywhere. I read that the 315983 will work as well, can anyone point me in the right direction? Not really excited about timing WOT on the water.

BTW I have been a marine mechanic with the USCG for 18 years, pretty decent with this stuff, just not an expert in mid 80's outboards lol. I do have a SELOC and CLYMERS manual for this engine.

 

[hardwater fisherman]

There are some videos on youtube that explain how to do timing at cranking speed without the motor running. Or there is a member here that gives good instruction on this. There is another recent post here about this.

 

[Scott Danforth]

before doing anything, verify the compression again. 90 psi is low.....

 

[boobie]

You can make a test wheel out of an old damaged prop by cutting the tips of the blades off equally.

 

[boobie]

If that motor is a looper the compression is not low. JMO.

 

[USCGCPOMK]

Wasn't sure on the compression, OMC doesn't really put out a recommended level, just says they should be within 10% of each other.

 

[interalian]

You can make a test wheel out of an old damaged prop by cutting the tips of the blades off equally.

Curious: how much do you leave on the hub? I have a ratty old prop that may be a candidate for such use.

 

[boobie]

If possible have 2/3 to 3/4 of the blade left on the hub.

 

[interalian]

Shape?

 

[flyingscott]

Forget about making a test wheel for the motor. Google joe reeves method for timing your motor. It can be done in the back yard and is much safer. If you make a test wheel you better make sure it has a good hub, because if it slips motor could be damaged or someone could get hurt.

 

[boobie]

Test wheels are used for more than just timing a motor. Good for trouble shooting high speed running problems among other things. I wouldn't have a shop with out them.

 

[USCGCPOMK]

Did the Reeves timing, seemed to work pretty good. Will confirm on the water. Just have to deal with the rest of the gremlins, thanks a lot.