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Old 01-31-2014, 07:27 PM   #41
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Mr. X. Short, sweet and to the point.

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Old 01-31-2014, 11:45 PM   #42
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Thanks. Appreciate the input from someone who's actually done it.

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Old 02-01-2014, 06:18 AM   #43
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The balance of any engine , and its harmonic periods awe well known to the engine builder.

I suspect the Ford Econo Power engine were balanced TO have their noise under 1000 RPM as it is not common for farm implements to operate at idle.

Should someone be doing a TOTAL rebuild , after the crank is straightened go and have ALL the moving stuff balanced.

Front shive and damper, crank and flywheel, pistons weight matched and rods checked for straight and equal weights end for end.

This is done on most high performance engines , and will cost under 1/2 a boat buck.

The difference in SMOOOTH will be felt , esp if the usual operating RPM is known to the engine balance shop.

Bigger engines have a damper on the front of the crank, no Idea if Leman does , but these wear out or rot .

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Old 02-01-2014, 08:44 AM   #44
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Idle shake of a in line six four stroke likely has nothing to do with balance of individual components. Always nice to have things in balance, but you will see no reduction in idle shake. Balance of those things shows up at high rev's where the inertial forces are much higher.

Straight six idle shake is simply due to the forces that come from compression and firing. It varies between engine brands due to the mass of the flywheels, mass of the block, mass of moving things like crank and other parts. All engines have it. The Ford seems to be no better or worse than others. What does vary is most Fords were installed with stiff mounts. They came from the factory with stiff mounts. That's why boats with Fords seem to rattle. Put the right mounts in, and the engine still shakes. But the boat does not rattle.

The Ford comes with a bonded-mass torsional damper, which does little to help idle shake. It is meant to damp torsional (twisting) vibrations at high speed. It provides little damping at idle. A viscous (fluid) type damper does help some with idle shake, but doubt one is available for that engine. Most Cat and Cummins do come from the factory with a viscous damper.

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