Mercury 1150 mounting.

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Mercury 1150 mounting. by jeramie reed on 24 Aug, 2018 22:32
I have a great running merc 1150 that I would like to install on a newer boat that had a standard OMC 4 bolt mounting. The merc has the bolts in the bottom but has clamp screws up top instead of bolts. I do not want to redrill. The later merc tower of power in the 80s used a standard 4 bolt OMC pattern. My question is can the older engine be installed on the newer mount or did they change something else to prevent that?
Reply #1 by Curt on 25 Aug, 2018 19:13
I wonder if @bullet20dc might know the answer to this one.
Reply #2 by jeramie reed on 25 Aug, 2018 23:06
I was thinking of possibly using a jack plate to mount it as an adapter.
Reply #3 by bullet20dc on 26 Aug, 2018 17:06
Im confused do u want to mount the 1150 on a jack plate and use a plate drilled for OMC on the boat side If thats the case the tower may work OK but I would find a way of removing the clamps and put in bolts. I dont think the clamps will close (thread) down far enough for the thin aluminum plate.
I hope you know what youre getting yourself in for changing from OMC to merc. Not a cheap ez job Nothing will work steering, gauges, throttle, engine harness all have to be changed over to merc. Good luck
Reply #4 by bullet20dc on 26 Aug, 2018 17:10
Oh btw when you mount it make sure the lower unit is at least 4 inches below the pad on that tower
Reply #5 by jeramie reed on 26 Aug, 2018 20:25
All the controls and engine wiring were junk and have already been removed. Well what was left anyway lol. Plan is to use all the stuff from the other boat as its all in decent shape. Big thing is I HAVE it so I'm going to use it. No sense buying another engine and controls when I have one that is in great shape lol. I was thinking of using a piece of square tube to thicken the top of the jack plate. Bolted in of course. Then install bolts where the clamps were.
Reply #6 by bullet20dc on 27 Aug, 2018 07:26
square tube may/will crush under load and you will be constantly tightening it till it fails At least put in crush proof sleeves inside the tube. I would try a solid piece tig welded into place. I know you are trying to do this with a small budget but safety has to come first. You dont want to be hitting a stump and have that motor come into the boat running. Saw that happen and what happened to the guy in the boat first hand. It wasnt pretty. All for the cost of a backing plate inside the transom. Forunatley he lived but got messed up really bad. Just an opinion.
Reply #7 by Curt on 27 Aug, 2018 10:08
@bullet20dc is absolutely right when it comes to safety! It always comes first!

I know how it is to be limited by a budget, but preventing life-threatening injuries is first and foremost
Reply #8 by jeramie reed on 27 Aug, 2018 13:26
Planned to fill the tube with a solid material or add bolt hole sleeves. And I am 100% with you on the safety aspect. I am budget minded however not to point of doing it half arsed. I planned to add a reinforcement plate inside the transom to prevent crushing at the bolt locations and to help spread the forces across the transom. This safety aspect is what lead me to swap hulls in the first place. The hull the engine is coming off of is severely rotted in the transom and decks. I imagine the stringers are shot as well. This newer hull is in 1000% better shape. I imagine I will need to change the prop once its on the water going to a completely different hull shape and size/weight. I am open to suggestions. Boat is an 84 Ranger 373v Moyer is a mid 70s merc 1150 115hp. With tilt/trim.
Reply #9 by bullet20dc on 28 Aug, 2018 07:22
17p or 19p tempest with vent holes depending on how strong that motor is more then likely 17p
Reply #10 by jeramie reed on 28 Aug, 2018 10:32
Ok thanks now I know where to start. I have heard a stainless prop will act quite different would you be recommending those numbers universally? Or would I need a different pitch in a SS prop? Thanks.
Reply #11 by bullet20dc on 28 Aug, 2018 18:29
the tempest is an ss prop