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Out drive to inboard coversion & lost rpms

 
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reel diamond



Joined: 15 Oct 2008
Posts: 2
Location: Baltimore, MD

PostPosted: Wed Oct 15, 2008 6:24 pm    Post subject: Out drive to inboard coversion & lost rpms Reply with quote

Well, I just spent a lot of money converting a 35' bay charter boat from a stern drive to a straight inboard. After the conversion I lost about 500 rpms under the curve (in neutral). Is this typical? Previously getting 4100r's now 3600r's. The engine is a VP KAMD42B. Work done to try to correct the problem: Changed all filters, Deisel straight to pump, and all new injectors. The fuel injector was serviced about 6 years ago and other then the rps it seems to run great. Any help would be GREATLY APPRECIATED! Thnaks, Charlie
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MikeW
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Joined: 01 May 2006
Posts: 680

PostPosted: Thu Oct 16, 2008 7:53 am    Post subject: Reply with quote

Hello reel diaqmond, I suspect it's the propeller. I would look into a propeller with 2" less pitch. Every inch you take out, the engine will gain 200 rpm's. The boat will perform much better when propped correctly. Cool
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reel diamond



Joined: 15 Oct 2008
Posts: 2
Location: Baltimore, MD

PostPosted: Thu Oct 16, 2008 9:06 am    Post subject: Reply with quote

Thanks Mike, But we have changed props a few times. Regaurdless it still has fewer RPMS in neutral. Thank You, Charlie
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boatScotty
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Joined: 07 Nov 2006
Posts: 229
Location: Pacific Northwest

PostPosted: Thu Nov 06, 2008 12:54 pm    Post subject: tuning? Reply with quote

I would then look at the engine.

Tune-up? Compression test?
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Boat Scotty

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jerome1



Joined: 05 Jun 2011
Posts: 1

PostPosted: Sun Jun 05, 2011 10:38 pm    Post subject: Re: Out drive to inboard coversion & lost rpms Reply with quote

reel diamond wrote:
Well, I just spent a lot of money converting a 35' bay charter boat from a stern drive to a straight inboard. After the conversion I lost about 500 rpms under the curve (in neutral). Is this typical? Previously getting 4100r's now 3600r's. The engine is a VP KAMD42B. Work done to try to correct the problem: Changed all filters, Deisel straight to pump, and all new injectors. The fuel injector was serviced about 6 years ago and other then the rps it seems to run great. Any help would be GREATLY APPRECIATED! Thnaks, Charlie



Still need an advice? I'm willing to help. Maybe your question answered already because this is an old thread.



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MikeW
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Joined: 01 May 2006
Posts: 680

PostPosted: Mon Jun 06, 2011 7:31 am    Post subject: Reply with quote

You need to change the propeller pitch.
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