[omc-boats] Re: omc-boats-digest V1 #581

In 1971 the auto guys changed horsepower ratings to accomodate emissions etc
on the new cars and that changed the HP ratings however the numbers went
down, I think as they were reporting netHP with all things attached rather
than raw HP as had been the previous. I remember some of this as I used to
hang around Corvettes in the 70s and 80s. TK
----- Original Message -----
From: "omc-boats-digest" <owner-omc-boats-digest@...>
To: <omc-boats-digest@...>
Sent: Tuesday, September 12, 2006 12:00 PM
Subject: omc-boats-digest V1 #581

>
> omc-boats-digest Tuesday, September 12 2006 Volume 01 : Number
> 581
>
>
>
> [omc-boats] Through Transom Exhaust
> [omc-boats] venting the cowling
> RE: [omc-boats] venting the cowling
> Re: [omc-boats] venting the cowling
> Re: [omc-boats] Through Transom Exhaust
> RE: [omc-boats] venting the cowling
> Re: [omc-boats] venting the cowling
>
> ----------------------------------------------------------------------
>
> Date: Mon, 11 Sep 2006 23:08:58 -0700
> From: "Scott E. Veazie" <scottveazie@...>
> Subject: [omc-boats] Through Transom Exhaust
>
> Would there be a horsepower increase by changing the exhaust from the
> stern
> drive to a through transom setup? I've always wondered this, besides the
> "muscle sound" gained going this route.
>
> ~Scott
>
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>
> ------------------------------
>
> Date: Mon, 11 Sep 2006 23:39:46 -0700
> From: "jdood" <jdood@...>
> Subject: [omc-boats] venting the cowling
>
> I have a 65 omc deluxe i/o that I know little about. I have been
> finding that it seems to be running better without the cowling on the
> engine. Perhaps my imagination, but I don't think so. So did those
> cowlings ever have vents in that nice flat section of the front that
> seems perfect for a vent grill? Would I be screwing anything up to put
> one in there? Those little grills in the back seem kind of useless.
>
> Thanks for any comments!
>
> jeff
>
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> 9/11/2006
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> ------------------------------
>
> Date: Tue, 12 Sep 2006 06:26:42 -0600
> From: "knight" <knight@...>
> Subject: RE: [omc-boats] venting the cowling
>
> I have a 69 rogue that is currently running at 6000 to 7000 feet above sea
> level. I completely built a taller cowling with plenty of vent screen.
> It defiantly runs better with all the air I can get to it. Try turning on
> your bilge blower and see if that helps too. Joe.
>
> - -----Original Message-----
> From: owner-omc-boats@... [mailto:owner-omc-boats@...]
> On
> Behalf Of jdood
> Sent: Tuesday, September 12, 2006 12:40 AM
> To: omc-boats@...
> Subject: [omc-boats] venting the cowling
>
>
>
> I have a 65 omc deluxe i/o that I know little about. I have been
> finding that it seems to be running better without the cowling on the
> engine. Perhaps my imagination, but I don't think so. So did those
> cowlings ever have vents in that nice flat section of the front that
> seems perfect for a vent grill? Would I be screwing anything up to put
> one in there? Those little grills in the back seem kind of useless.
>
> Thanks for any comments!
>
> jeff
>
> - --
> No virus found in this outgoing message.
> Checked by AVG Free Edition.
> Version: 7.1.405 / Virus Database: 268.12.3/444 - Release Date:
> 9/11/2006
>
>
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>
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>
> ------------------------------
>
> Date: Tue, 12 Sep 2006 08:20:56 -0500
> From: David <odin@...>
> Subject: Re: [omc-boats] venting the cowling
>
> It wouldn't hurt anything to put a vent in - but I think I would put it
> on the port side of the cowling - where the carb is located since you
> wouldn't see it there - Dave
>
> jdood wrote:
>
>> I have a 65 omc deluxe i/o that I know little about. I have been
>>finding that it seems to be running better without the cowling on the
>>engine. Perhaps my imagination, but I don't think so. So did those
>>cowlings ever have vents in that nice flat section of the front that
>>seems perfect for a vent grill? Would I be screwing anything up to put
>>one in there? Those little grills in the back seem kind of useless.
>>
>>Thanks for any comments!
>>
>>jeff
>>
>>
>>
> - -----
> To get off this list send mail to omc-boats-unsubscribe@...
>
> ------------------------------
>
> Date: Tue, 12 Sep 2006 08:34:42 -0600
> From: <lib1@...>
> Subject: Re: [omc-boats] Through Transom Exhaust
>
> Another good question that actually has some historical background.
>
> Just after OMC quit building our boats and sold the molds and rights to
> Chris Craft in 1970-71 they increased the rated power of their small block
> 307 Chevy V8.
>
> In the 19-footer E/J's that OMC built the 307 was rated at 210 hp. This
> was
> in models years 1969-1970.
>
> In 1971 they bumped the 210 to 215 and as far as I can tell from
> researching
> parts manuals no parts were changed in the process. Perhaps someone in
> engineering got a better dynomometer, who knows?
>
> But in 1971, they also introduced a 235 hp 307 Chevy. (Not to be confused
> with the later Ford-based 235 hp electric stringer). These 235 hp Chevies
> were painted red (as opposed to gray) and had Corvette/Camaro Z-28 cast
> aluminum valve covers. Theses engines also had the more agressive Corvette
> camshafts and THRU-THE-TRANSOM exhausts. They didn't idle down as well as
> the 210-215's but they sure do sound cool (or annoying depending on your
> point of view)! Not a lot were sold but you see them in the early
> Pachanga's
> (a Donzi-like v-hull boat).
>
> The in 1972 -74 OMC upped ante again and moved the 215 to 225. The
> "Corvette-Based" 235 jumped to 245. The engines were built to OMC's spec's
> by Chevy as they never offered a 307 in their car or truck lines with the
> QuadraJet and the hot Corvette camshaft. The OMC shifted focus to 302 and
> 351 Fords and the short-shaft stringer and Chevy 307 was phased out. There
> are more 225/245's out there than 215/235's becuase they were made for a
> couple years longer. As far as I can tell 210-215-225's are all the carb,
> cams, and heads. An the same applies to the 235/245's which are indentical
> twins as well.
>
> My advice (and this is based on talking to experienced OMC mechanics) is
> to
> leave well enough alone. About all you will accomplish in changing the
> exhaust is a lot more sound, er noise. You may think you're going faster
> but
> the power gains will practically un-detectable. That's because they
> engineered the back-pressure and matched it verywell to the 210-215-225's
> exhaust manifolds and camshaft. A hotter cammed 290-hp 350 might need less
> back pressure, but not our engines. Even the thru-hub exhaust of the
> 400-800
> stringer probably didn't add more than fractional horsepower gains.
>
> Probably more than you really cared to know......
>
> Lee Shuster
> Salt Lake City
>
> - ----- Original Message -----
> From: "Scott E. Veazie" <scottveazie@...>
> To: <omc-boats@...>
> Sent: Tuesday, September 12, 2006 12:08 AM
> Subject: [omc-boats] Through Transom Exhaust
>
>
>> Would there be a horsepower increase by changing the exhaust from the
>> stern drive to a through transom setup? I've always wondered this,
>> besides the "muscle sound" gained going this route.
>>
>> ~Scott
>> -----
>> To get off this list send mail to omc-boats-unsubscribe@...
>>
>
> - -----
> To get off this list send mail to omc-boats-unsubscribe@...
>
> ------------------------------
>
> Date: Tue, 12 Sep 2006 08:32:23 -0700
> From: "jdood" <jdood@...>
> Subject: RE: [omc-boats] venting the cowling
>
> So if the engine runs better with vents, now I am wondering why they
> didn't put them in originally? Noise? Or is there some special
> marine/safety issue with venting it?
>
> - -----Original Message-----
> From: owner-omc-boats@... [mailto:owner-omc-boats@...]
> On Behalf Of David
> Sent: Tuesday, September 12, 2006 6:21 AM
> To: omc-boats@...
> Subject: Re: [omc-boats] venting the cowling
>
> It wouldn't hurt anything to put a vent in - but I think I would put it
> on the port side of the cowling - where the carb is located since you
> wouldn't see it there - Dave
>
> jdood wrote:
>
>> I have a 65 omc deluxe i/o that I know little about. I have been
>>finding that it seems to be running better without the cowling on the
>>engine. Perhaps my imagination, but I don't think so. So did those
>>cowlings ever have vents in that nice flat section of the front that
>>seems perfect for a vent grill? Would I be screwing anything up to put
>>one in there? Those little grills in the back seem kind of useless.
>>
>>Thanks for any comments!
>>
>>jeff
>>
>>
>>
> - -----
> To get off this list send mail to omc-boats-unsubscribe@...
>
> - --
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.1.405 / Virus Database: 268.12.3/444 - Release Date:
> 9/11/2006
>
>
> - --
> No virus found in this outgoing message.
> Checked by AVG Free Edition.
> Version: 7.1.405 / Virus Database: 268.12.3/444 - Release Date:
> 9/11/2006
>
>
> - -----
> To get off this list send mail to omc-boats-unsubscribe@...
>
> ------------------------------
>
> Date: Tue, 12 Sep 2006 10:57:02 -0500
> From: David <odin@...>
> Subject: Re: [omc-boats] venting the cowling
>
> This is a multi-part message in MIME format.
> - --------------070905040703020903050202
> Content-Type: text/plain; charset=us-ascii; format=flowed
> Content-Transfer-Encoding: 7bit
>
> Probably never noticed it - during my stint in engineering at OMC I ran
> a lot of hours testing on Lake Michigan - there were several other OMC's
> out on endurance that ran everyday - I do not recall ever seeing anyone
> run with the engine cover off - so it is likely no one ever had the
> chance to notice the difference - Dave
>
> jdood wrote:
>
>>So if the engine runs better with vents, now I am wondering why they
>>didn't put them in originally? Noise? Or is there some special
>>marine/safety issue with venting it?
>>
>>-----Original Message-----
>>From: owner-omc-boats@... [mailto:owner-omc-boats@...]
>>On Behalf Of David
>>Sent: Tuesday, September 12, 2006 6:21 AM
>>To: omc-boats@...
>>Subject: Re: [omc-boats] venting the cowling
>>
>>It wouldn't hurt anything to put a vent in - but I think I would put it
>>on the port side of the cowling - where the carb is located since you
>>wouldn't see it there - Dave
>>
>>jdood wrote:
>>
>>
>>
>>>I have a 65 omc deluxe i/o that I know little about. I have been
>>>finding that it seems to be running better without the cowling on the
>>>engine. Perhaps my imagination, but I don't think so. So did those
>>>cowlings ever have vents in that nice flat section of the front that
>>>seems perfect for a vent grill? Would I be screwing anything up to put
>>>one in there? Those little grills in the back seem kind of useless.
>>>
>>>Thanks for any comments!
>>>
>>>jeff
>>>
>>>
>>>
>>>
>>>
>>-----
>>To get off this list send mail to omc-boats-unsubscribe@...
>>
>>
>>
>
> - --------------070905040703020903050202
> Content-Type: text/html; charset=us-ascii
> Content-Transfer-Encoding: 7bit
>
> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
> <html>
> <head>
> <meta content="text/html;charset=windows-1250"
> http-equiv="Content-Type">
> <title></title>
> </head>
> <body bgcolor="#ffffff" text="#000000">
> Probably never noticed it - during my stint in engineering at OMC I ran
> a lot of hours testing on Lake Michigan - there were several other
> OMC's out on endurance that ran everyday - I do not recall ever seeing
> anyone run with the engine cover off - so it is likely no one ever had
> the chance to notice the difference - Dave<br>
> <br>
> jdood wrote:<br>
> <blockquote cite="mid017401c6d680$a56f2380$0a00a8c0@..." type="cite">
> <pre wrap="">So if the engine runs better with vents, now I am wondering
> why they
> didn't put them in originally? Noise? Or is there some special
> marine/safety issue with venting it?
>
> - -----Original Message-----
> From: <a class="moz-txt-link-abbreviated"
> href="mailto:owner-omc-boats@...">owner-omc-boats@...</a>
> [<a class="moz-txt-link-freetext"
> href="mailto:owner-omc-boats@...">mailto:owner-omc-boats@...</a>]
> On Behalf Of David
> Sent: Tuesday, September 12, 2006 6:21 AM
> To: <a class="moz-txt-link-abbreviated"
> href="mailto:omc-boats@...">omc-boats@...</a>
> Subject: Re: [omc-boats] venting the cowling
>
> It wouldn't hurt anything to put a vent in - but I think I would put it
> on the port side of the cowling - where the carb is located since you
> wouldn't see it there - Dave
>
> jdood wrote:
>
> </pre>
> <blockquote type="cite">
> <pre wrap="">I have a 65 omc deluxe i/o that I know little about. I
> have been
> finding that it seems to be running better without the cowling on the
> engine. Perhaps my imagination, but I don't think so. So did those
> cowlings ever have vents in that nice flat section of the front that
> seems perfect for a vent grill? Would I be screwing anything up to put
> one in there? Those little grills in the back seem kind of useless.
>
> Thanks for any comments!
>
> jeff
>
>
>
> </pre>
> </blockquote>
> <pre wrap=""><!---->-----
> To get off this list send mail to <a class="moz-txt-link-abbreviated"
> href="mailto:omc-boats-unsubscribe@...">omc-boats-unsubscribe@...</a>
>
> </pre>
> </blockquote>
> </body>
> </html>
>
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>
> ------------------------------
>
> End of omc-boats-digest V1 #581
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Received on Tuesday, 12 September 2006