Test Prop

[kax2000]

Setting Maximum Spark Advance on J50TLEOD.
Service manual says to run the engine with the correct test propeller and not to use the the regular propeller or a flushing adapter for this adjustment.
Is a test prop typically used when setting maximum spark advance on outboard motors?

 

[retiredfornow]

Re: Test Prop

Read this.
http://forums.iboats.com/showthread.php?t=514030&highlight=full+advance+timing

 

[retiredfornow]

Re: Test Prop

And this
http://forums.iboats.com/showthread.php?t=228183

 

[emdsapmgr]

Re: Test Prop

That's the easiest way for the dealer to check for max timing at his shop-assuming that he has an engine test tank. There are other methods used to get the same results. An OMC tech used to back the trailer partway down into the water at the launch ramp. When the engine water intake holes were adequately covered with water, he'd crank it up to 5000 in gear and set the timing. An unorthodox method-but it works

 

[Haffiman]

Re: Test Prop

That's the easiest way for the dealer to check for max timing at his shop-assuming that he has an engine test tank. There are other methods used to get the same results. An OMC tech used to back the trailer partway down into the water at the launch ramp. When the engine water intake holes were adequately covered with water, he'd crank it up to 5000 in gear and set the timing. An unorthodox method-but it works

I guess that he in order to manage to obtain those 5000 rpm and a boat 'not moving' he must have used a 'test prop'!!

 

[emdsapmgr]

Re: Test Prop

No, he used the existing prop that was on the boat, a 26 raker. No test wheel required. It was on a 1979 200 Evinrude. I've also see an OMC master tech set max timing on V6 engines with stock props in a dealership test tank-again no test wheel.

 

[Haffiman]

Re: Test Prop

. I've also see an OMC master tech set max timing on V6 engines with stock props in a dealership test tank-again no test wheel.

If so I would not call him a 'Master Tech'!

 

[emdsapmgr]

Re: Test Prop

Mercury outboards, Mercruiser and Bombardier do. You are entitled to your opinion.

 

[boobie]

Re: Test Prop

Emdsapmgr, as long as you get the 5000 rpm you're okay as I've done it myself. Maybe Haffi hasn't had that much experience.

 

[Haffiman]

Re: Test Prop

Maybe I'm a bit more concerned about safety aspects and proper test equipment than obtaining a result at any cost. I may have done some unorthodox things in my past, but putting them out on a board, mainly for advice to novice mechanics, I 'm not quite prepared to do.

 

[jimmbo]

Re: Test Prop

I doubt an engine could attain its rated RPM on a trailer using a high pitch prop. unless it was Ventilating severely

 

[boobie]

Re: Test Prop

I don't believe it was ever mentioned here about running the boat at WOT across a lake and setting the timing. In both cases the boat and mtr were stationary.

 

[Haffiman]

Re: Test Prop

I doubt an engine could attain its rated RPM on a trailer using a high pitch prop. unless it was Ventilating severely

You simply adjust the rpm with your trim! A risky business both for the gearbox, cooling, operator and not to forget if anyone is in the vicinity of the rooster tail you most likely create!

 

[boobie]

Re: Test Prop

And yes you have to get them to ventilate to get the rpms up. And you run the mtr for a very SHORT period of time.