4 inch engine mount design?

[Josh784]

I am in the process of building a Wild Thing, and for the next step in the assembly I need to have a rubber isolated motor mount for a .21 engine. Rather than spend $40 to buy one, I plan on making my own as they seem fairly simple. I have access to Solid Works and CNC equipment, but I need some idea of where to start.

Does anyone have any diagrams of an engine mount they have made? It would be nice if I didn't have to CNC it, but I don't mind going to the extra trouble if it is neccessary.

Thanks,

Josh

 

[Kez]

Josh,

I have a simple way of shock mounting my engines. I made an engine plate mount out of 3/16" aluminum for .20 and 1/4" for .40 and bigger much like the Dumas mounting plates. Then I shape two hardwood engine bearers (maple or birch) to be glued and bolted to the hull. There should be about 1/4" gap between the aluminum plate and the harwood mount.

Then I simple draw two beads of silicon sealant (RTV) and glue the aluminum plate to the mount. You will need to use something to shim the plate while the glue set so the alignment will be correct. In fact, I have used a length of solid 3/16" shaft that fit into the stuffing box and the collet.

The silicon will provide enough give for vibration abosrption and they are surprisingly tough. I have one that lasted 4 seasons before needing replacement.

Reagrds,

Kez

 

[Preston_Hall]

Josh,

I used the attached motor mount with rubber bushings #9376K143 from McMaster Carr. The mount is tapped for a Novarossi.

However I believe you would benefit from a drop down mount such as Speedmaster's or Seaducer's.

 

[Eric Perez]

You can also use a piece of hardwood with similar dimensions (for those of you that do not have access to metal cutting equipment) Seal the wood with a couple of thin coats of good epoxy and you will not have to worry about durability.

To avoid using brass inserts for the engine screws drill the mount from the top all the way to the bottom and use washers and a lock nut to hold the engine bolts in. Removal of engine will require you to unsecure the mount from the hull's side plates, but it's really not a big deal.