Steel motor mount examples/plans?

erikgreen

Captain
Joined
Jan 8, 2007
Messages
3,105
Hi, all;

I'm completing a refit of my boat, including a tear-out and rebuild of the motor mounts at the front of my Mercruiser 260 (Chevy 350) engine.

Basically what was there were two 6x6 pillars of fiberglass and wood standing about 7 inches off my hull bottom.

I'd like to replace them instead with a steel mount welded together that provides that 7 inch lift off the hull. I want to do this for more clearance to reach around and under the motor. Plus they won't rot (I know, they may rust....)

Note that I'm not suggesting replacement of the standard front motor "legs" since this would force me to include a vertical adjustment method in my welded mount, which I'm thinking would take a lot of effort to build and test. A simple short frame 7 inches high that attaches to the engine stringers, the bulkhead forward of the engine, and maybe somewhere else should be doable.

What I'm looking for is anyone who has done this and has a pic or a plan. I know you can get "offshore" motor mounts for mercruisers, but they're not adjustable, plus I haven't seen one that isn't designed for dual engines.

Here's a rough sketch of what I'm thinking (sorry for using MSPaint):

mm.png


The mercruiser "legs" are in gray and the proposed steel mount is in blue.. the solid lines are square tubing and the rectangle on the stringer is piece of channel over the stringer top. There would also be a horizontal bar running from side to side at the same place the front "leg" attaches near the top.

Sane idea or no? Anyone done this? Should I just build the frame to attach directly to the engine and shim it to the right height?

Erik
 

frank246

Petty Officer 1st Class
Joined
Jul 18, 2009
Messages
293
Re: Steel motor mount examples/plans?

Somtin` like this?
The frame is bolted to the stringer(s) and the adjustable engine mounts bolted to the top plates on the frame.
 

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frank246

Petty Officer 1st Class
Joined
Jul 18, 2009
Messages
293
Re: Steel motor mount examples/plans?

Well, yea I made the frame.
It`s made out of 4"x2" 304 stainless then powder coated.
It now supports a 302 in my 16 ft boat instead of the original 140 4 cyl.:D
It is doable so good luck fabricating !
 

erikgreen

Captain
Joined
Jan 8, 2007
Messages
3,105
Re: Steel motor mount examples/plans?

I can see how it's done pretty well, but I don't suppose you have a sketch of it anywhere?

I'll be making mine from (probably) 1.5" square 14 gauge tubing and angle iron... I'm guessing you went with SS to avoid/stop corrosion?

Erik
 

oops!

Supreme Mariner
Joined
Oct 18, 2007
Messages
12,932
Re: Steel motor mount examples/plans?

hi buddy....

robj has a really cool motor mount system on his boat......find his posts in my thread.....and there is a link to his project....

dont forget to add rubber behind any metal to further help the isolators
 
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