Repowering 1979 and raising engine bed

[Robert1224]

Ahoy,

My re-power is progressing and I am to the point of modifying the engine bed for the new engine. I am going to have to raise the bed approximately 2.5 inches to get the necessary alignment. The decision to be made is whether to use square steel tubing, aluminum block or treated oak which is then epoxied using the West System or something similar. Has anyone raised the engine bed in their H30 before and if so, how? Also, any experience or thoughts oh the best way to do it will certainly be considered and appreciated.

Thanks!
Bob

 

[ggrizzard]

Yep, had to when I repowered to a 2GM20F. Not as much elevation change as you need but I used 1 in. epoxied wood in an upside 'L' shape as the engine mounts were also narrower.
Good luck with your project.
G

 

[Robert1224]

G,
Thanks for the info! I am curious, what type of wood did you choose and did you epoxy it using the West System? Also, have you had any issues with the dimensional stability of wood? Swelling or shrinking that altered prop alignment?
Thanks,
Bob

 

[Robert1224]

More questions,

Any reason not to use square steel tubing? I found out I can get 3 1/2 x 2 1/2, 11 gauge and that is the right size for the application. I just talked with a marine mechanic who said it was a tough question and that he could see himself going either way.

Thanks,
Bob

 

[kito]

You can also buy 316 stainless square tubing too. That's the route I would probably take. How are you mounting it? Lag bolts through the tube and into the floor? My motor mounts on my H30 were just lag bolted. I am not sure that's the best option with your setup though.

 

[Ed Schenck]

Noise might be a problem with the square tubing. I realize the mounts are rubber but the vibration on a steel tube would be something to consider. You would be lag bolting it through the side and into the existing wood mounts. So the weight of the engine is on those sideways lag bolts. You can't support it from the bottom, the engine pan is not solid enough. I think wood mounts epoxied and lagged onto the sides of the original mounts would be my preference.

 

[kito]

I was thinking it was just a 2-1/2" elevation change with no sideways adjustment. Basically placing the tubing under where the old mounts were.

 

[Robert1224]

Kito,

Yes correct.
The steel tubing would be going on top of the old runners, extending beyond the edge perhaps 1/2 inch with the support being provided by the original runners from the original setup. The original runners are sound and have held up well and the new runners will be lag bolted to them. Ed has a point that is well founded relative to increased noise. Hence, pro's and cons for both methods.

Regards,
Bob

 

[ggrizzard]

I used Brand X epoxy due to size of container (Too Much from West) and cost. Wood was oak.
You'd need a narrower stance than 1/2 inch extra spacing per side for a 2GM29F engine. And the installer also mentioned the noise/vibration factor with metal
spacers.

 

[Allan12210]

When I changed from non traditional motor mounts, I needed to raise the engine bed by about 2 inches. To fill the gap, I used slotted aluminum (or Unistrut). It comes in different sizes. It made it very easy as I did not need to drill any holes. I was able to insert carriage bolts into the holes in the existing steel angle bed and bolt the motor mounts to the engine with more carriage bolts facing up. Then it was a simple matter of inserting and sliding the Unistrut into place. The final installation used a full length (2 feet long) on each side. Luckily all the prior motor mount mounting holes in the steel were in a straight line. Tighten the nuts and done. Some alignment is necessary as per usual.

I don't know if your configuration is similar, but the extruded aluminum has worked well for me for many years. Searching the web will give sources.

 

[braol]

You can also buy 316 stainless square tubing too. That's the route I would probably take. How are you mounting it? Lag bolts through the tube and into the floor? My motor mounts on my H30 were just lag bolted. I am not sure that's the best option with your setup though.

Yes, stainless steel square tubing. I would also put a barrier of some sort between the new engine and the tubing...like tar paper or roofing shingle.

 

[FastOlson]

We had to raise our four engine mounts about 1 1/2" and did it with layers of half-inch G-10 fiberglass plate material.
Longer ss lags inserted. Worked perfectly.