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Old 06-25-2016, 09:28 AM   #21
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"Black soot and smoke for about the first 5 minutes then it cleans up but still not getting rpm"


This 'clue' if it is accurate would leave me to believe that it is not necessarily the turbo's . If they were not spooling at all the black smoke would not get any better and in some case get much worse.
Hard to define these things from a distance as it is somewhat subjective about amounts of black smoke.
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Old 06-25-2016, 09:32 AM   #22
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"The boat will not plan out and only pulls 2200 wot"

If tachs are accurate and both engines are limited to 2,200 you either have two engines that are equally overloaded or two engines with similar problems.
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Old 06-25-2016, 10:03 AM   #23
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exactly and the similar problems are usually boat related not engine related, often dirty bottom and over pitched props.
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Old 06-25-2016, 10:06 AM   #24
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"exactly and the similar problems are usually boat related not engine related, often dirty bottom and over pitched props."


Yes - agreed 100% , lacking more input here to be able to pin it down completely.
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Old 06-25-2016, 10:42 AM   #25
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you should double check bottom and prop condition, these must be clean for optimum performance.
if the boat is capable of the performance you are seeking, I have no knowledge on that score, and you are trying to get 2600 rpm at wot underway then you will need to start with around 3000 rpm at high idle (wot in neutral).
check rpm with a proper tach, not the dials on the panel, then set high idle by adjusting the stop screw on the speed control lever.
strongly advise fitting boost gauges, even if only temporary (if you dont want the panel work).
remove air filters and sea trial after all the above and record results.
if you get continuous black smoke, not just a few wisps but plenty of it, it could be turbos problem, full load boost pressure should be around 20 psi if I recall correctly for this engine.
if boost pressure is 20 or above it isnt the turbos and then either the boat is too heavy for the prop / transmission fitted...or the engines are worn out !!
you can have the latter confirmed by blow by testing.
btw, if you intend to run the boat at that speed apart from using a lot of fuel you will soon have worn out engines, if they arent already.
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Old 06-25-2016, 11:50 AM   #26
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"and you are trying to get 2600 rpm at wot underway then you will need to start with around 3000 rpm at high idle (wot in neutral)."


I am curious why you say this - governor 'droop' should be 60-70 rpm which will translate to 120-140 at the crankshaft.
Confirming rated rpm plus 200 should be fine - 2600+200=2800
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Old 06-25-2016, 11:57 AM   #27
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6B's with CAV pumps should be about 2900-3000 high idle if rated for 2600. Lots of droop on these.
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Old 06-25-2016, 12:05 PM   #28
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Thank you Ski - I have not seen that with my strobe tachs on these engines myself.
It is good to know that ...thanks
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