Test Tank Wheel Question

AguaSki

Chief Petty Officer
Joined
Jul 4, 2005
Messages
545
Is a test wheel really necessary to do a synchronization and linkage adjustment? My manual contains the following warning, "CAUTION - This procedure should be performed in a test tank with the proper test wheel installed on the engine. The use of the propeller and/or a flushing device can result in an incorrect setting and possible engine damage". I was thinking of going to the boat ramp and backing the trailer into the water with the transom tie-downs still attached and running the motor with a regular prop. Can I do that or do I need a test wheel?
 

DHPMARINE

Captain
Joined
Dec 16, 2003
Messages
3,688
Re: Test Tank Wheel Question

The test wheel lets you hold it at max rpm,for as long as needed.

DHP
 

AguaSki

Chief Petty Officer
Joined
Jul 4, 2005
Messages
545
Re: Test Tank Wheel Question

So where do you find a test wheel and approximately how much does one cost? I don't seem to find too much with my Google searches. Are there any alternatives to the test wheel?

The motor is a 1978 Johnson v4 140hp.
 

alden135

Lieutenant Commander
Joined
Sep 1, 2004
Messages
1,770
Re: Test Tank Wheel Question

I saved this "how to" from Joe Reeves. Maybe it will help you.

"The full spark advance can be adjusted without have the engine running at near full throttle as follows.

To set the timing on that engine, have the s/plugs out, and have the throttle at full, set that timer base under the flywheel tight against the rubber stop on the end of the full spark timer advance stop screw (wire it against that stop if necessary).

Rig a spark tester and have the spark gap set to 7/16". Hook up the timing light to the #1 plug wire. Crank the engine over and set the spark advance to 4° less than what the engine calls for.

I don't know full spark advance setting your engine calls for, but to pick a figure, say your engine calls for 28°, set the timing at 24°. The reasoning for the 4° difference is that when the engine is actually running, due to the nature of the solid state ignition componets, the engine gains the extra 4°.

If you set the engine to its true setting at cranking speed, when running it will advance beyond its limit by 4° which will set up pre-ignition causing guaranteed piston damage! You don't want that to take place.

No need to be concerned about the idle timing as that will take care of itself. The main concern is the full advance setting.

Be sure to use your own engines spark advance settings, not the one I picked out of the air here in my notes."

....................................................................................

I bought my test prop on ebay for $65.
 

wilde1j

Vice Admiral
Joined
Apr 15, 2002
Messages
5,964
Re: Test Tank Wheel Question

"I was thinking of going to the boat ramp and backing the trailer into the water with the transom tie-downs still attached and running the motor with a regular prop. Can I do that or do I need a test wheel?"

The Joe Reeves method for link & sync is fine and you don't have to run the motor. Your method of testing is OK, especially to confirm you got it right.
 
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