I'm new to gas engines. I have a Zenoah G38 going on an Ikon Stinson SR-8. I bought a GP big engine resilient mount. According to the GP instructions, attach the engine directly to the plywood, and then the rubber bushed mounts to the firewall. OK, but the engine to plywood joint has four 1/4-20 screws going thru the 1/4 thick plywood into the back of the engine. It seems like this joint is inadequate. When torqued, the bolts will compress the plywood, leaving it wothout much preload. It would seem better if there were hard sleeves in the plywood to limit the compression, and longer bolts with stiff spacers to develop a good preload.
Maybe it works as supplied, but it looks all wrong to me. Any comments?
Thanks.

G38s have been working just fine for over 20 years with no resilient mount at all...

RCIGN1....Thanks for the reply. If I don't need a resilient mount, so much the better. but it still doesn't answer my question. If I put four 1/4-20 bolts thru a 1/4 inch thick piece of plywood into the engine and tighten the bolts, what keeps them tight? The wood will compress, reducing the preload to almost nothing.

Thanks,
Mike hopkins

Mike,

Because of vibration in gas engines, you need to be using blue Loctite on the engine mounting bolts. Just tighten the bolts and check them periodically during your maintenance checks.

Off the subject, I'm considering building the Ikon Waco. Can you tell me what you think of the quality, ease of building their kit? You can PM me if you want.

Chuck

To keep the wood from compressing, install large diameter washers (fender washers) on each bolt. These will distribute the load.

You can also harden the plywood with a small application of thin CA.