hi there,

I've been tinkering with a 1972 80hp merc that I got some time ago that
started, but has since failed to. It appears there may be a problem in
either the switch, and / or coil. Based on the prices of these old parts it
could be pretty pricey if they both need replacing (which I wouldn't doubt).
My alternative to just not fixing it, is to get another motor that is newer
and in good working condition for a bit more. I'm keeping my eye out on
those prices too, but have an important question to consider... Could I use
a smaller motor?

This old 80hp has powered a 15.5 ft fiberglass boat. But could a newer
motor of a smaller HP do an equal or pretty good job? Perhaps a 40hp of a
newer vintage?

Has anyone had experience changing motor sizes?

Chris

Around 4/14/2005 3:05 PM, Chris wrote:

This old 80hp has powered a 15.5 ft fiberglass boat. But could a newer
motor of a smaller HP do an equal or pretty good job? Perhaps a 40hp of a
newer vintage?

Though a 40 would probably work on a 15.5' depending on weight, you
should probably stick with at _least_ a 50. I'd personally prefer a 70
or higher, but that's just me (see disclaimer below).

As an aside, what's the boat's max HP rating? A good rule of thumb is to
get as close to that rating as you can afford.

My 14' used to have a 50 Merc, and frankly, though I _love_ my current
40 Nissan, I do occasionally miss those few extra HP.





Disclaimer: My family has a long history of overpowering small boats. I
grew up bombing around in my great uncle's barebones 14.5' Livingston
powered by that same 50 Merc... Let's just say that I know what a
skipping rock feels like.

--
~/Garth - 1966 Glastron V-142 Skiflite: "Blue-Boat"
"There is nothing - absolutely nothing - half so much worth doing
as simply messing about in boats."
-Kenneth Grahame, The Wind in the Willows

I have every part that motor could ever need - used and in stock.

-W

"Chris" wrote in message
. ..
hi there,

I've been tinkering with a 1972 80hp merc that I got some time ago that
started, but has since failed to. It appears there may be a problem in
either the switch, and / or coil. Based on the prices of these old parts
it
could be pretty pricey if they both need replacing (which I wouldn't
doubt).
My alternative to just not fixing it, is to get another motor that is
newer
and in good working condition for a bit more. I'm keeping my eye out on
those prices too, but have an important question to consider... Could I
use
a smaller motor?

This old 80hp has powered a 15.5 ft fiberglass boat. But could a newer
motor of a smaller HP do an equal or pretty good job? Perhaps a 40hp of a
newer vintage?

Has anyone had experience changing motor sizes?

Chris

And if you wish - I can talk you through a troubleshoot of the ignition.

1st test: Red on the switchbox (starbord side of box) outta be at +12 all
the time, when you turn the key on white will go +12. Switch is now tested.
Let me know when you get that far.

-W

"Clams Canino" wrote in message
ink.net...
I have every part that motor could ever need - used and in stock.

-W

"Chris" wrote in message
. ..
hi there,

I've been tinkering with a 1972 80hp merc that I got some time ago that
started, but has since failed to. It appears there may be a problem in
either the switch, and / or coil. Based on the prices of these old
parts
it
could be pretty pricey if they both need replacing (which I wouldn't
doubt).
My alternative to just not fixing it, is to get another motor that is
newer
and in good working condition for a bit more. I'm keeping my eye out on
those prices too, but have an important question to consider... Could I
use
a smaller motor?

This old 80hp has powered a 15.5 ft fiberglass boat. But could a newer
motor of a smaller HP do an equal or pretty good job? Perhaps a 40hp of
a
newer vintage?

Has anyone had experience changing motor sizes?

Chris

Hello there,

As far as troubleshooting so far I've been using the clymer shop manual for
1972-1989 45-225hp, as well as mercury service manual of the early 70s
vintage that covers the motor to some extent as well.

The interesting thing is that the switchbox on this motor is not one that
has the white post. Actually due to the serial number in the 319 level the
box has only 4 posts - red, blue, green, and brown (based on the book, and
from what I've seen). The service manual suggests a different way for
testing outside of using the key on and white to 12+. (The other serial
numbers use that type of check though). The way includes putting #1 to TDC,
and grounding the blue on the switch box, removing the ground and thus
triggering a spark to #1. Well this didn't work.

I'm amazed at how to properly check the coil and switch someone still needs
to take it to a mercury dealer for the use of a special tool. With all the
advances in technology, and cheap technology at that, I'd think there would
be a way to test this with one of today's gadgets you pickup at the local
automotive shop.. but I suppose not....

So the next steps over the next 1-2 weeks is to get the parts into a dealer
and have them checked with this special tool....

C



"Clams Canino" wrote in message
ink.net...
And if you wish - I can talk you through a troubleshoot of the ignition.

1st test: Red on the switchbox (starbord side of box) outta be at +12 all
the time, when you turn the key on white will go +12. Switch is now
tested.
Let me know when you get that far.

-W

"Clams Canino" wrote in message
ink.net...
I have every part that motor could ever need - used and in stock.

-W

"Chris" wrote in message
. ..
hi there,

I've been tinkering with a 1972 80hp merc that I got some time ago that
started, but has since failed to. It appears there may be a problem in
either the switch, and / or coil. Based on the prices of these old
parts
it
could be pretty pricey if they both need replacing (which I wouldn't
doubt).
My alternative to just not fixing it, is to get another motor that is
newer
and in good working condition for a bit more. I'm keeping my eye out
on
those prices too, but have an important question to consider... Could I
use
a smaller motor?

This old 80hp has powered a 15.5 ft fiberglass boat. But could a newer
motor of a smaller HP do an equal or pretty good job? Perhaps a 40hp
of
a
newer vintage?

Has anyone had experience changing motor sizes?

Chris

another question,

would a coil from a new merc 80 work on the 72? say perhaps a 1978-1980
80hp coil?


"Chris" wrote in message
. ..
Hello there,

As far as troubleshooting so far I've been using the clymer shop manual
for 1972-1989 45-225hp, as well as mercury service manual of the early 70s
vintage that covers the motor to some extent as well.

The interesting thing is that the switchbox on this motor is not one that
has the white post. Actually due to the serial number in the 319 level
the box has only 4 posts - red, blue, green, and brown (based on the book,
and from what I've seen). The service manual suggests a different way for
testing outside of using the key on and white to 12+. (The other serial
numbers use that type of check though). The way includes putting #1 to
TDC, and grounding the blue on the switch box, removing the ground and
thus triggering a spark to #1. Well this didn't work.

I'm amazed at how to properly check the coil and switch someone still
needs to take it to a mercury dealer for the use of a special tool. With
all the advances in technology, and cheap technology at that, I'd think
there would be a way to test this with one of today's gadgets you pickup
at the local automotive shop.. but I suppose not....

So the next steps over the next 1-2 weeks is to get the parts into a
dealer and have them checked with this special tool....

C



"Clams Canino" wrote in message
ink.net...
And if you wish - I can talk you through a troubleshoot of the ignition.

1st test: Red on the switchbox (starbord side of box) outta be at +12 all
the time, when you turn the key on white will go +12. Switch is now
tested.
Let me know when you get that far.

-W

"Clams Canino" wrote in message
ink.net...
I have every part that motor could ever need - used and in stock.

-W

"Chris" wrote in message
. ..
hi there,

I've been tinkering with a 1972 80hp merc that I got some time ago
that
started, but has since failed to. It appears there may be a problem
in
either the switch, and / or coil. Based on the prices of these old
parts
it
could be pretty pricey if they both need replacing (which I wouldn't
doubt).
My alternative to just not fixing it, is to get another motor that is
newer
and in good working condition for a bit more. I'm keeping my eye out
on
those prices too, but have an important question to consider... Could
I
use
a smaller motor?

This old 80hp has powered a 15.5 ft fiberglass boat. But could a
newer
motor of a smaller HP do an equal or pretty good job? Perhaps a 40hp
of
a
newer vintage?

Has anyone had experience changing motor sizes?

Chris

On Thu, 14 Apr 2005 18:05:36 -0400, "Chris"
wrote:

hi there,

I've been tinkering with a 1972 80hp merc that I got some time ago

I had four of these mounted on an old Master Craft. It ran in the
upper 80s.

I would think a newer 50hp in good condition should be better than an old 80
with potentially lower compression, etc...

The real thing is , how much does one put into an old motor, when a
newer-used motor is an option? Correct me if I'm wrong, but aren't all the
parts on the old 1972 motors fairly expensive these day?

I've seen some used motors ranging from 50-90hp of I think the 80's vintage
for anywhere between 500-1800 cdn...

When do you stop spending money on an old motor?


"Garth Almgren" wrote in message
...
Around 4/14/2005 3:05 PM, Chris wrote:

This old 80hp has powered a 15.5 ft fiberglass boat. But could a newer
motor of a smaller HP do an equal or pretty good job? Perhaps a 40hp of
a newer vintage?

Though a 40 would probably work on a 15.5' depending on weight, you should
probably stick with at _least_ a 50. I'd personally prefer a 70 or higher,
but that's just me (see disclaimer below).

As an aside, what's the boat's max HP rating? A good rule of thumb is to
get as close to that rating as you can afford.

My 14' used to have a 50 Merc, and frankly, though I _love_ my current 40
Nissan, I do occasionally miss those few extra HP.





Disclaimer: My family has a long history of overpowering small boats. I
grew up bombing around in my great uncle's barebones 14.5' Livingston
powered by that same 50 Merc... Let's just say that I know what a skipping
rock feels like.

--
~/Garth - 1966 Glastron V-142 Skiflite: "Blue-Boat"
"There is nothing - absolutely nothing - half so much worth doing
as simply messing about in boats."
-Kenneth Grahame, The Wind in the Willows

I suppose my question is simply this: based on your knowledge of what it
takes to properly push a boat, here's a model, now what do you think the
minimum horsepower required to push this would be?

1975 15'5 Sunray (Fiberglass boat)

50hp?
60hp?
70hp?
80hp (this is what it currently has)



"Chris" wrote in message
. ..
hi there,

I've been tinkering with a 1972 80hp merc that I got some time ago that
started, but has since failed to. It appears there may be a problem in
either the switch, and / or coil. Based on the prices of these old parts
it could be pretty pricey if they both need replacing (which I wouldn't
doubt). My alternative to just not fixing it, is to get another motor that
is newer and in good working condition for a bit more. I'm keeping my eye
out on those prices too, but have an important question to consider...
Could I use a smaller motor?

This old 80hp has powered a 15.5 ft fiberglass boat. But could a newer
motor of a smaller HP do an equal or pretty good job? Perhaps a 40hp of a
newer vintage?

Has anyone had experience changing motor sizes?

Chris

For my use 80 would be the minimum. Your use may require less.

My current boat is 16' FRP and it's powered with a 115 hp OB.

I'm not familiar with a Sunray. If it is a lightweight skiff it may do well
with only 80 hp. However, in my experience FRP boats from the seventies
tended to be heavily built.

Butch
"Chris" wrote in message
...
I suppose my question is simply this: based on your knowledge of what it
takes to properly push a boat, here's a model, now what do you think the
minimum horsepower required to push this would be?

1975 15'5 Sunray (Fiberglass boat)

50hp?
60hp?
70hp?
80hp (this is what it currently has)



"Chris" wrote in message
. ..
hi there,

I've been tinkering with a 1972 80hp merc that I got some time ago that
started, but has since failed to. It appears there may be a problem in
either the switch, and / or coil. Based on the prices of these old parts
it could be pretty pricey if they both need replacing (which I wouldn't
doubt). My alternative to just not fixing it, is to get another motor
that is newer and in good working condition for a bit more. I'm keeping
my eye out on those prices too, but have an important question to
consider... Could I use a smaller motor?

This old 80hp has powered a 15.5 ft fiberglass boat. But could a newer
motor of a smaller HP do an equal or pretty good job? Perhaps a 40hp of
a newer vintage?

Has anyone had experience changing motor sizes?

Chris