[C320-list] Am I slow under power?

[Nathan Mauch]

Thanks.  
With the lever pushed to the stop, the engine will not go over 2300 rpm under load, at which point I was doing 5.3 knots (clean prop/bottom).  
My exhaust elbow blew up recently (on delivery!) and is brand new from Catalina.  I'm thinking I should check the rest of the exhaust system now, as maybe that is the issue. The water out the back seems to come out under quit a bit of pressure, too.  
-Nate

--- On Tue, 4/17/12, guyhenry22 at aol.com <guyhenry22 at aol.com> wrote:

From: guyhenry22 at aol.com <guyhenry22 at aol.com>
Subject: Re: [C320-list] Am I slow under power?
To: C320-List at Catalina320.com
Date: Tuesday, April 17, 2012, 9:31 AM


Nate,

Another possiblity.
Do the RPMs top out before the throttle handle is at full throttle?

Given that you are not getting the RPMs that you think you should at full 
throttle, you may have a restriction in fuel or cooling/exhaust.

A restricted fuel flow will obviously imped your ability to reach full 
throttle.

A restricted cooling/exhaust is less obvious, but a strong possibility 
especially if you are in salt water. The elbow coming off the back of the 
exhaust manifold/heat exchanger is an elbow in an elbow and mixes the sea 
water with the exhaust and sends it to the muffler. If this elbow is 
restricted, as it very well may be after 15 years, it will stop you from 
reaching full throttle. While the elbow is off, you should be able to look 
through the core of the heat exchanger to ensure it is not clogged.

I see you have Yanmar, I have the Perkins, so my description of how this 
looks may be slightly different.

Guy
MoonShadow #115




-----Original Message-----
From: Nathan Mauch <nmauch at yahoo.com>
To: C320-List <C320-List at Catalina320.com>
Sent: Tue, Apr 17, 2012 7:22 am
Subject: [C320-list] Am I slow under power?


I'm a pretty new C320 owner and I'm trying to figure out whether I have a 
achometer issue or an throttle governor issue (3GM30F) on my '97 #453.   At 
ull throttle, I make 5.3 knots in a dead calm, but my tach is only reading 2200 
PM, which I know is well below rated max.  However, I've seen my tach wander 
nd I'm not convinced it's working properly.
y question is, is 5.3 knots about right for this boat (15X10 prop) at full 
hrottle, or is my tach corret and I'm not geting full RPM out of the engine? 
Reading through previous posts, it sounds like I should be getting at or close 
o hull speed?
hanks,Nate,S/V Mistral