Re: [OMC-Boats] Engine RPM and Boat Speed

From: Don Mandelas <dmandelas@...>
Date: Sun, 27 Jul 2008 23:26:35 -0700

Well, Just to let everyone know.
Last week I followed Lee Schusters advise and contacted Roy Hansen who owns an OMC certified repair shop in Salt Lake City. According to Roy (and I'll relay this information as best as I can remember) a possible reason why I may be traveling slower than normal at 3,500 rpms may be that the Lower unit forward clutch hub and/or forward clutch spring may have worn causing the hub not to engaged the propeller shaft fully. He advised me that a new forward clutch hub/and or forward clutch spring may be needed. He advised me that if I wanted, in order to save some money, I could swap the clutch spring from the reverse hub and place it in the forward hub (Since both hubs use the same spring on my lower unit). I found Roys information very interesting and In the future I may try replacing the forward hub and spring.
This weekend I was able to obtained a timing light and digitally measure the revalutions per minute of my V-6 155 hp boat engine.
I discovered that when the timing light indicated 1,100 RPM's my boat tachometer was reading 1,000 RPM's. And, when the timing light indicated 4,000 RPM's my boat tachometer was reading 3,000 RPM's. This means my tachometer is reading a full 1,000 rpms below what it should be on the higher end of the scale and is probably the primary reason why I am going slower than normal. I'll replace the tachometer and try the boat again.
Thanks again for everyones help,
Don Mandelas
Washington State.
> ----- Original Message ----- > From: "Kenneth Fingerlos" <>> To: <omc-boats@...>> Sent: Tuesday, July 22, 2008 9:03 PM> Subject: Re: [OMC-Boats] Engine RPM and Boat Speed> > > > Don -> >> > Please do let us know what you find out; I've got a 1968 Seasport-II 155 > > with similar issues; Slower than Lee's stuff says it should be and I'm > > running a 19" stainless prop. Seems like I've got plenty of power, can't > > run it at WOT because it'll over-rev, but really can't get above 30MPH. > > Slippage somewhere sounds like a very interesting idea - had a car once > > with a bad clutch which behaved kinda similarly.> >> > Kenneth Fingerlos> > Northern Idaho> >> >>>> On Tuesday, July 22, 2008 at 7:21 PM, > >>>> <omc-boats-request@...>> >> Message: 4> >> Date: Tue, 22 Jul 2008 19:09:00 -0700> >> From: Don Mandelas <dmandelas@...>> >> Subject: Re: [OMC-Boats] Engine RPM and Boat Speed.> >> To: "Evinrude & Johnson Boats of the 1960's and 70's"> >> <>> >> Message-ID: <BLU118-W13EE6EF795282C3898E244DA840@...>> >> Content-Type: text/plain; charset="iso-8859-1"> >>> >>> >> Thank's Again everyone for your help and advice!> >> You have given me some good ideas that could help fix my problem.> >>> >> Starting Tommorow morning I will look into the tackometer issue to see if > >> it> >> is reading correctly,> >> And, I will contact a qualified OMC repair man to see what can be done if> >> the forward clutch hub is slipping.> >>> >> And Thank you for asking, Yes, I am using Type C lower unit gear lube.> >> Don Mandelas> >> Washington State.> >> > _______________________________________________> > OMC-Boats mailing list> > OMC-Boats@...> > > > > _______________________________________________> OMC-Boats mailing list> OMC-Boats@...>
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Received on Monday, 28 July 2008

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