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Old 23-05-2011, 11:36   #1
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Engine Alignment Tolerance

I am checking engine alignment after working on the propeller strut.

I am in the water. Have loosened the coupling. Checking coupler variation with a feeler gauge. I am about .004 What is the ideal reading? What is the goal in this situation? Thanks
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Old 23-05-2011, 12:56   #2
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Re: Engine Alignment Tolerance

Gap recommendation is no more than .001 for every inch in diameter of the coupling. If you have a 4 inch coupling then you are within tolerance. Sounds like you are there.

"This old boat" Don Casey.

kind regards,
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Old 23-05-2011, 13:27   #3
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Re: Engine Alignment Tolerance

Quote:
Originally Posted by SkiprJohn View Post
Gap recommendation is no more than .001 for every inch in diameter of the coupling. If you have a 4 inch coupling then you are within tolerance. Sounds like you are there.
"This old boat" Don Casey.
kind regards,
Also according to the Westerbeke Propí shaft Alignement Instruction
http://www.pearson35.com/projects/ma...llManual10.pdf

See also a couple of relevant articles by David Pascoe:

Drive System Alignment
Marine Engines : Drive System Alignment by David Pascoe, Marine Surveyor

Troubleshooting Problems Involving Engine/Shaft Alignment
Marine Engines : Engine-Shaft Alignmnet - Troubleshooting by David Pascoe, Marine Surveyor
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Old 23-05-2011, 13:56   #4
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Re: Engine Alignment Tolerance

The goal is zero, but no one ever really reached that. .003 has always seemed achievable in most cases, but if you don't know for sure if the coupling faces are true, you're just spinning your wheels. It's not hard to have the shaft side coupling out by two or three thousandths, and shooting for even .004 will frustrate you.
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