Roger Long wrote:
Bob wrote:
But there are some folks that say "upgrade" to more modern model.

Modern isn't always better.
Roger Long

Hi, good point.
I had a conversation with a shop manager at my local GM (car) dealer.
My 1994 car toasted a
heater blower switch and had it replaced in 2000. It failed after 2 ½
years. I put in another one and it failed after 3 years. Each was
genuine GM parts from my genuine GM dealer.

The shop manager explained to me that engineers use computers now and
design more efficiently (insert wise crack here). These efficient
designs reduce the once common and expensive practice of over building
parts that contained wasted potential and added to unwanted weight and
increased costs. My response was, and reduced unit reliability! No
response from the shop manager.

I like to keep things simple. A rebuild and easy replacement sounds a
lot les frustrating than hoping for a similar foot print and all the
potential adapting. My motor lives under the sink in the middle of my
galley. I aint got but an inch any way around for clearance. Great for
engine access when I pull all the covers but I imagine a bear to make
something different fit.

But scheesh... when I sell the boat in 20 years who is going to buy a
boat with a 50 year old motor obviously with at leaser one rebuild?!?!

**** that statement is dumb, who is going to buy a 50 year old boat!?!?
Bob

Bob,

Your original post no longer shows up but I think from some responses I may
have missed the point that your engine is salt water cooled. If that is the
case, I would not rebuild it. My engine was run in fresh water till I
bought the boat so is probably worth an overhaul.

I was told at a boat show that the new Yanmars drop right into the same
space as the old ones. These are great engines and a new 3GM is probably
your best bet.

BTW more often than not when I'm advising someone on repowering a sailboat,
I'll find that they have a 3 cylinder engine but a prop that can only use
the horsepower of a 2 cylinder. You very well might be able to put in a
lighter and cheaper 2GM that would be happier running closer to its design
point and give you the same performance you have now. It wouldn't be quite
as smooth but the 2QM running a 2 blade prop in my boat is as smooth as I
could ask for. Fuel economy will also be slightly better taking the same
horsepower out of one less cylinder. The 2GM should fit easily on the same
beds as the 3GM with more room at one end.

I can give you a rough answer on this if you tell me:

Displacement
Length on Waterline

I can give you a better answer if you an also tell me:

Current HP and reduction gear ratio
Prop size, pitch' and number of blades
Propeller aperture size
C
Current max RPM and speed at that RPM

--
Roger Long

Roger Long wrote:
I can give you a rough answer on this if you tell me:

Displacement
Length on Waterline

I can give you a better answer if you an also tell me:

Current HP and reduction gear ratio
Prop size, pitch' and number of blades
Propeller aperture size
C
Current max RPM and speed at that RPM
Roger Long

Hi Roger:
Thanks for the reply. Yes, my QM is a raw water engine. I need to dig
out my manual for the Hurth-18 gear ratio. 2.37 may be the answer but I
need to check And this is another issue: I read the hurth18 was a
special model for the qm only. A rare pair with no parts availble. Seem
to remember a post about having to ceate a modifed flange and fit
another hurth gear on the QMs. My head hurts thinking about this.
Ill post the specs you requesed in a couple days. Thank you for
offering your time on this.
Bob

On Sun, 21 Jan 2007 09:27:42 -0500, "Roger Long"
wrote:

Your original post no longer shows up but I think from some responses I may
have missed the point that your engine is salt water cooled. If that is the
case, I would not rebuild it.

That's an excellent point, and I agree 100%.

You can not save a block with significant amounts of internal rust.