Join Date: Jan 2003
Location: Maine Coast
Thanked 270 Times in 207 Posts
Rep Power: 17
1- Confirm the engine will run to 3600 RPM in neutral (I believe this is the "one hour" load RPM for the 3GM)
2- Confirm with a photo tach that the tachometer is reading correctly
3- Make sure your fuel filters are clean and the exhaust elbow is not restricted.
4-Confirm bottom and prop are clean
If all the above check out then the prop is most likely over-pitched. This can usually be fixed by a pitch adjustment but with a high of 2400 on an engine that should be able to hit about 3400 it may require more than just pitch adjustment. A very rough guideline is 200-300 RPM for every inch of pitch adjustment. It is unlikely you can take 3" of pitch on a prop that has possibly been re-pitched at some point in its life span.
You should be able to attain at least max continuous, which is 3400 on the 3GM, or max one hour rating, about 3600, at WOT with a clean bottom and prop.
-Maine Sail / CS-36T
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Last edited by Maine Sail; 10-18-2010 at 06:09 PM.