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Old 10-08-2016, 08:39 AM   #4
DavidM
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City: Litchfield, Ct
Join Date: Aug 2012
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Well, the issue of over propping has been debated extensively on this forum. Do a search and you will find at least 100 opinions on the subject- for and against.


But there is one thing that all 100 would agree on- running an over propped engine at wot is very bad for it. You are putting much more stress on the engine than it was ever designed for.


Also 900 rpm is very low for routine cruising and may not be enough to put sufficient load on the engine to get it up to full operating temps. That is one reason why you are seeing accumulated soot after running that low.


I think the best thing that you can do (short of propping the engine right) is to run at no lower than 1,200 rpm and then run it up to say 1,800 every 10 hours or so to blow out the soot. That should do the job without putting too much stress on the engine.


David
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