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Author Topic:   1978 MONTAUK, 115-HP

roverguy posted 03-13-2012 06:50 PM ET (US)
[The author begins by telling the reader that he] bought a mint [1978 Boston Whaler] Montauk. [I] want to put on [an Evinrude E-TEC 90-HP], but cash a little short right now. A neighbor is selling me his nice clean [1995] Mercury 115-HP for short money. I was thinking about putting [the Mercury 115-HP] on my 17-footer for a season or two [until] I can muster enough [money] for a new 90.
My wife and I just tool around Massachusetts Bay, usually over to Crane Beach, and most trips are no more than three miles from Port; although we may make a run to Rockport which is about five miles along the coast. mI don't plan on skiing, or tubing, mostly to the beach or Bass and Blue fishing. So, despite it being over the maximum 100-HP rating, what do you folks think, aside from the [problem of obtaining insurance]? Can I prop-down? Or adjust the full open throttle in the event my [19-year-old] wants to take it out? My dad had a [1969] Sakonnet with a tower-of-power 90 and that thing flew! Thanks
Teak Oil posted 03-13-2012 07:07 PM ET (US)
You can run [a 115-HP engine] on the Montauk, but since [115-HP is] overpowered--as you know--there could be liability.
[The static trim of the hull] will sit a little lower in the back than [it would with] a 90, but it should not be a game breaker. With a 115 you would see close to 50-MPH, which should only be done when the water is very calm. It is not too hard to get a Montauk flying when over 40-MPH.
You can run it, it will just be a little squirrely at top end
jimh posted 03-13-2012 07:51 PM ET (US)
What does it mean to "prop-down"?
KDW posted 03-15-2012 11:46 AM ET (US)
My Dad's old 1971 Nauset came with 125 HP Johnson and no tilt and trim unit. Light boat and light motor. Now that thing would really fly.
We used to chase striper schools on Lake Moultrie in the lower part of S.C. I think it's one of the reason my knees are bad from banging across the lake on the bow locker cover and holding on to the rails for dear life!
outragesteve posted 03-15-2012 01:48 PM ET (US)
I had the same rig: 1976 Montauk, 115 Merc 6 cylinder "tower of power" engine. The boat was nothing short of spectacular! Rigged with hydraulic steering, 14" Gil Offshore bracket and Merc "HighFive" 22" prop speeds were in the high 50's. I could run (GPS) over 60 mph using a Merc 24" thin blade chopper prop. No problem pulling up a slalom skier (I have a ski pylon custom made). I used the boat also for deep sea trolling and it performed great. I moved up to a 22' Outrage, but really miss my Montauk. Good luck!
L H G posted 03-15-2012 05:26 PM ET (US)
Hey Steve, was your Montauk something along the lines of this one? Prop is a 22" Laser II.
http://smg.photobucket.com/albums/v429/lgoltz/Montauk%2017/?action=view& current=Scan_Pic0009.jpg
outragesteve posted 03-16-2012 01:29 PM ET (US)
Larry: The Merc Chopper was a prop I had Ron Hill (California) make for me. It was thinned and if I recall, started out as a 24" pitch, can't remember the diameter. It had quite a bit of bow lift. This was not really an issue since I was using the Gil 13" modVP bracket. The stock prop I used most of the time was a Merc "High Five" 13 x 22. (smaller gear case diameter compared to the V6 props). Part # for this prop was 48-815744A6. Fun!
L H G posted 03-16-2012 02:29 PM ET (US)
Thanks, Steve. That must have been quite a rig!
Getting back to the original poster, the 4 cylinder Merc 115 2 + 2 should be a good engine on a Montauk, since it is only about 30# heavier than the Evinrude 90 he eventually plans to install. I have seen quite a few of these installations. These are strong engines, and pretty good on gas, and I even saw one push a MUCH heavier Outrage 19 over 40 MPH.
You will have to watch out for the 1800 RPM situation where the other 2 cylinders kick in as the boat accelerates. It will really take off! I would say it will run around 50 MPH and suggest a 22" Laser II prop. Gears are 2.07. This series of Mercury engines have a VERY long shaft length, so I would mount it up in the 3rd or 4th set of holes.
After having this kind of power on the boat, you may not want to go back to the considerably less power of the 90 E-tec.
Mike Kub posted 03-20-2012 06:59 PM ET (US)
Do you guys that have larger than 100hp. engines on the 16'7" hull have any issues from your insurance co.?
roverguy posted 03-20-2012 08:04 PM ET (US)
Well; got my mooring guy to come over tonight with his pickup with rear mounted winch arm. Took us about 45 mins to get the motor off as we didn't have the lifting ring. We made a nice 4 point sling that worked quite well. We couldn't get enough lift height to get it the bed of the truck so we drove, very slowly about a block and down my long driveway without incident.
Temporarily dropped on the stern of my Montauk and put in two bolts. Fortunately the exist top holes lined up nicely for width. Used the 3rd holes with bracket about 3-4 inches above the top of the transom. Not so sure about the bottom holes; it was getting dark.
The motor looks pretty big!
Took about 2 hours in all; offered the guy some cash, he said $40; I thought we would be an hour and had a $50 in my pocket, told him I'd like to give him $75, he said, no how about $40! He got the $50 and my thanks; he said he loved doing this stuff.
Nice guy; whom I know from the waterways committee and I have helped him on logging his GPS locations of the mooring fields.
I"m trying to keep this simple; initially will run a compression test and then try draining the float bowls, changing the in line fuel filter, a little spritz of oil in cylinders and see if I can get her running without rebuilding the carbs. Good thing is the motor was shut down prior to E10 fuel.
Any other thoughts?
Thanks
Teak Oil posted 03-20-2012 08:31 PM ET (US)
If there is varnish fuel in the bowls there will certainly be varnish in the carbs. One plugged jet can ruin a cylinder.
Taking he carbs apart and cleaning them is not that hard, and well worth the 20 bucks in carb kits
Tohsgib posted 03-21-2012 01:00 AM ET (US)
You also do NOT need carb kits if you are cautious taking them apart.
roverguy posted 03-21-2012 01:34 PM ET (US)
your probably right about the rebuild; I just didn't want to hear it.
However the 70HP-1978 that came on my Montauk was mothballed for almost 10 years and started up on 3rd try and ran and started fine after that...
roverguy posted 03-21-2012 01:41 PM ET (US)
Can someone give me a measurement from the top of cavitation plate to the lowest point of keel at the transom so I can set the motor up?
Thanks.
Tohsgib posted 03-22-2012 03:26 PM ET (US)
Don't go by that. You want the engine about 1.5-2" above the transom to start. I would go as high as possible and then go down if needed.
jimh posted 03-22-2012 08:07 PM ET (US)
What does it mean "to prop down"?
roverguy posted 03-22-2012 08:45 PM ET (US)
When I said "prop down", I guess I was thinking I could change the pitch, but then again I guess it would just change the acceleration and revs?? Bottom line is I'd like to reduce top end as a safety measure if the kids are using the boat; maybe through linkage adjust/stop?
As for the motor, I ran a compression test tonight 125 straight across the board. I sprayed a bit of engine store to be sure the cyls were lubed up. No bad fuel smell so I hooked up a tank of 2 stroke from last season and gave it a try. It started on 3rd try and peed water after a minute or so. Idled down nice and seemed to run good, despite the 2 stroke mix. Had it running for 10-15 mins and started up on almost 1 click.
Only issue so far is the horn stays on with key on, and also when running.
I'm going to run the diag tomorrow per manual and see if it's the temp sensor.
It actually took me longer to get the motor and controls off the old boat than to drop it on my boat and get it running.
Will keep you posted, thanks.
Teak Oil posted 03-22-2012 09:44 PM ET (US)
The horn may be from the oil injection pump not working correctly or the temp sensor.
You should change the water pump impeller in the lower unit. Even though it works now the rubber dries out when not in use, and they are famous for lasting just far enough for you to get away from shore and then the rubber impeller disintegrates.
outragesteve posted 03-23-2012 02:16 PM ET (US)
On most Mercs. the audible horn has two functions: Over heat (temp sensing) and oil reservoir levels. If the alarm is steady, problem is usually engine temperature related. If the alarm beeps, it is usally oil system related. I have had a bad alarm module cause either senario. The alarm system does not sense water flow, water pressure, or sense oil flow. If either system does actually fail, 1.e. no water (cooling) or inadequate oil (lubrication)the results can be catosprophic to any engine. Good luck!
jimh posted 03-23-2012 04:06 PM ET (US)
It would be risky to intentionally run the 115-HP engine with a propeller whose pitch was too small. The engine could easily be run to over-speed in that case. You might damage the engine.
roverguy posted 03-26-2012 12:04 PM ET (US)
Did a little more research, motor is 25" shaft. Thought my dealer would give me something on trade, but he has a backlog of 100's.
I am listing in in classified, if anyone is interested.
Turns out it's the temp sensor as I did the diagnostics & engine runs nice and cool.
roverguy posted 03-28-2012 07:41 PM ET (US)
Sold, Thanks, closer to an Etech every day!

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Author	Topic: 1978 MONTAUK, 115-HP
roverguy	posted 03-13-2012 06:50 PM ET (US) [The author begins by telling the reader that he] bought a mint [1978 Boston Whaler] Montauk. [I] want to put on [an Evinrude E-TEC 90-HP], but cash a little short right now. A neighbor is selling me his nice clean [1995] Mercury 115-HP for short money. I was thinking about putting [the Mercury 115-HP] on my 17-footer for a season or two [until] I can muster enough [money] for a new 90. My wife and I just tool around Massachusetts Bay, usually over to Crane Beach, and most trips are no more than three miles from Port; although we may make a run to Rockport which is about five miles along the coast. mI don't plan on skiing, or tubing, mostly to the beach or Bass and Blue fishing. So, despite it being over the maximum 100-HP rating, what do you folks think, aside from the [problem of obtaining insurance]? Can I prop-down? Or adjust the full open throttle in the event my [19-year-old] wants to take it out? My dad had a [1969] Sakonnet with a tower-of-power 90 and that thing flew! Thanks
Teak Oil	posted 03-13-2012 07:07 PM ET (US) You can run [a 115-HP engine] on the Montauk, but since [115-HP is] overpowered--as you know--there could be liability. [The static trim of the hull] will sit a little lower in the back than [it would with] a 90, but it should not be a game breaker. With a 115 you would see close to 50-MPH, which should only be done when the water is very calm. It is not too hard to get a Montauk flying when over 40-MPH. You can run it, it will just be a little squirrely at top end
jimh	posted 03-13-2012 07:51 PM ET (US) What does it mean to "prop-down"?
KDW	posted 03-15-2012 11:46 AM ET (US) My Dad's old 1971 Nauset came with 125 HP Johnson and no tilt and trim unit. Light boat and light motor. Now that thing would really fly. We used to chase striper schools on Lake Moultrie in the lower part of S.C. I think it's one of the reason my knees are bad from banging across the lake on the bow locker cover and holding on to the rails for dear life!
outragesteve	posted 03-15-2012 01:48 PM ET (US) I had the same rig: 1976 Montauk, 115 Merc 6 cylinder "tower of power" engine. The boat was nothing short of spectacular! Rigged with hydraulic steering, 14" Gil Offshore bracket and Merc "HighFive" 22" prop speeds were in the high 50's. I could run (GPS) over 60 mph using a Merc 24" thin blade chopper prop. No problem pulling up a slalom skier (I have a ski pylon custom made). I used the boat also for deep sea trolling and it performed great. I moved up to a 22' Outrage, but really miss my Montauk. Good luck!
L H G	posted 03-15-2012 05:26 PM ET (US) Hey Steve, was your Montauk something along the lines of this one? Prop is a 22" Laser II. http://smg.photobucket.com/albums/v429/lgoltz/Montauk%2017/?action=view& current=Scan_Pic0009.jpg
outragesteve	posted 03-16-2012 01:29 PM ET (US) Larry: The Merc Chopper was a prop I had Ron Hill (California) make for me. It was thinned and if I recall, started out as a 24" pitch, can't remember the diameter. It had quite a bit of bow lift. This was not really an issue since I was using the Gil 13" modVP bracket. The stock prop I used most of the time was a Merc "High Five" 13 x 22. (smaller gear case diameter compared to the V6 props). Part # for this prop was 48-815744A6. Fun!
L H G	posted 03-16-2012 02:29 PM ET (US) Thanks, Steve. That must have been quite a rig! Getting back to the original poster, the 4 cylinder Merc 115 2 + 2 should be a good engine on a Montauk, since it is only about 30# heavier than the Evinrude 90 he eventually plans to install. I have seen quite a few of these installations. These are strong engines, and pretty good on gas, and I even saw one push a MUCH heavier Outrage 19 over 40 MPH. You will have to watch out for the 1800 RPM situation where the other 2 cylinders kick in as the boat accelerates. It will really take off! I would say it will run around 50 MPH and suggest a 22" Laser II prop. Gears are 2.07. This series of Mercury engines have a VERY long shaft length, so I would mount it up in the 3rd or 4th set of holes. After having this kind of power on the boat, you may not want to go back to the considerably less power of the 90 E-tec.
Mike Kub	posted 03-20-2012 06:59 PM ET (US) Do you guys that have larger than 100hp. engines on the 16'7" hull have any issues from your insurance co.?
roverguy	posted 03-20-2012 08:04 PM ET (US) Well; got my mooring guy to come over tonight with his pickup with rear mounted winch arm. Took us about 45 mins to get the motor off as we didn't have the lifting ring. We made a nice 4 point sling that worked quite well. We couldn't get enough lift height to get it the bed of the truck so we drove, very slowly about a block and down my long driveway without incident. Temporarily dropped on the stern of my Montauk and put in two bolts. Fortunately the exist top holes lined up nicely for width. Used the 3rd holes with bracket about 3-4 inches above the top of the transom. Not so sure about the bottom holes; it was getting dark. The motor looks pretty big! Took about 2 hours in all; offered the guy some cash, he said $40; I thought we would be an hour and had a $50 in my pocket, told him I'd like to give him $75, he said, no how about $40! He got the $50 and my thanks; he said he loved doing this stuff. Nice guy; whom I know from the waterways committee and I have helped him on logging his GPS locations of the mooring fields. I"m trying to keep this simple; initially will run a compression test and then try draining the float bowls, changing the in line fuel filter, a little spritz of oil in cylinders and see if I can get her running without rebuilding the carbs. Good thing is the motor was shut down prior to E10 fuel. Any other thoughts? Thanks
Teak Oil	posted 03-20-2012 08:31 PM ET (US) If there is varnish fuel in the bowls there will certainly be varnish in the carbs. One plugged jet can ruin a cylinder. Taking he carbs apart and cleaning them is not that hard, and well worth the 20 bucks in carb kits
Tohsgib	posted 03-21-2012 01:00 AM ET (US) You also do NOT need carb kits if you are cautious taking them apart.
roverguy	posted 03-21-2012 01:34 PM ET (US) your probably right about the rebuild; I just didn't want to hear it. However the 70HP-1978 that came on my Montauk was mothballed for almost 10 years and started up on 3rd try and ran and started fine after that...
roverguy	posted 03-21-2012 01:41 PM ET (US) Can someone give me a measurement from the top of cavitation plate to the lowest point of keel at the transom so I can set the motor up? Thanks.
Tohsgib	posted 03-22-2012 03:26 PM ET (US) Don't go by that. You want the engine about 1.5-2" above the transom to start. I would go as high as possible and then go down if needed.
jimh	posted 03-22-2012 08:07 PM ET (US) What does it mean "to prop down"?
roverguy	posted 03-22-2012 08:45 PM ET (US) When I said "prop down", I guess I was thinking I could change the pitch, but then again I guess it would just change the acceleration and revs?? Bottom line is I'd like to reduce top end as a safety measure if the kids are using the boat; maybe through linkage adjust/stop? As for the motor, I ran a compression test tonight 125 straight across the board. I sprayed a bit of engine store to be sure the cyls were lubed up. No bad fuel smell so I hooked up a tank of 2 stroke from last season and gave it a try. It started on 3rd try and peed water after a minute or so. Idled down nice and seemed to run good, despite the 2 stroke mix. Had it running for 10-15 mins and started up on almost 1 click. Only issue so far is the horn stays on with key on, and also when running. I'm going to run the diag tomorrow per manual and see if it's the temp sensor. It actually took me longer to get the motor and controls off the old boat than to drop it on my boat and get it running. Will keep you posted, thanks.
Teak Oil	posted 03-22-2012 09:44 PM ET (US) The horn may be from the oil injection pump not working correctly or the temp sensor. You should change the water pump impeller in the lower unit. Even though it works now the rubber dries out when not in use, and they are famous for lasting just far enough for you to get away from shore and then the rubber impeller disintegrates.
outragesteve	posted 03-23-2012 02:16 PM ET (US) On most Mercs. the audible horn has two functions: Over heat (temp sensing) and oil reservoir levels. If the alarm is steady, problem is usually engine temperature related. If the alarm beeps, it is usally oil system related. I have had a bad alarm module cause either senario. The alarm system does not sense water flow, water pressure, or sense oil flow. If either system does actually fail, 1.e. no water (cooling) or inadequate oil (lubrication)the results can be catosprophic to any engine. Good luck!
jimh	posted 03-23-2012 04:06 PM ET (US) It would be risky to intentionally run the 115-HP engine with a propeller whose pitch was too small. The engine could easily be run to over-speed in that case. You might damage the engine.
roverguy	posted 03-26-2012 12:04 PM ET (US) Did a little more research, motor is 25" shaft. Thought my dealer would give me something on trade, but he has a backlog of 100's. I am listing in in classified, if anyone is interested. Turns out it's the temp sensor as I did the diagnostics & engine runs nice and cool.
roverguy	posted 03-28-2012 07:41 PM ET (US) Sold, Thanks, closer to an Etech every day!