Whats your opinion, mount directly to the firewall or use a rubber spacer
to absorb some of the vibration. I've heard strong explanations in both directions
so now I don't know .......
Craig

13 hits and no reply ? ? no thoughts ? ? coments ??

On my first engine installation I used rubber spacers and later changed to mounting with 1/4-20 carriage bolts used as standoffs. I saw no benefit from rubber spacers.

Bill

same here i used rubber the first time but found it useless so i went to mounting all my gassers straight to the firewall

hard mount to firewall.

Yep, hard mount. And I don't use a plate like most people do. Just adds weight. On the Homelites, I just install long studs to mount the engine backplate. Then I use nuts to hold the backplate on, add some flat washers, and then the studs go through the firewall with nuts on back.

The Kioritz/Echo engines are even simpler, as there is no backplate, but there are four mounting holes that I use in the same manner. A little dicey on some designs to get at the nuts inside the fuselage, but it saves the weight of the plate mount, plus either having to buy or make one.

AV8TOR

Av8tor,
On my Kioritz there are 4 tapped holes on the back of the case, do you use those and run bolts through the firewall? I wasn't sure if they would be strong enough, seemed a little small.

Pete

Yes, those are the holes I use. No problems in many hours of use. Use loctite on the stud threads where they screw into the engine.

AV8TOR

Yes, those are the holes I use. No problems in many hours of use. Use loctite on the stud threads where they screw into the engine.

AV8TOR

How long can the bolts be before it can cause a problem?

I mounted a G-62 this way and the engine shakes quite a bit at idle.

The way I mount the ones I'm speaking of, the engine fits tight against the firewall so the studs don't have to be very long; only slightly longer than the firewall is thick. I wouldn't use the studs as standoffs to mount the engine farther forward. For that you need proper aluminum standoffs.

AV8TOR

Ralph,

The bolts I used as standoffs extend 1 3/4� from the firewall. A lock nut is used on each side of the engine plate. Three engines have been mounted in the airplane in a similar manner. The firewall has been knocked out twice. The standoff bolts held up but the firewall did not.

Bill

I have 6 conversion motors, all hard mounted to the firewall. Like they say above, if you need the stand off space use posts. Most of mine are WWI planes so I just mount the backplate directly to the firewall. Here is an example of one of mine, I needed to clear the mounting bolts and cooling fins on the back. Briggs and Stratton four stroke gas engine. Flies my Fokker DVII great, no shaking.

Well, thank you all for your input. The reason I asked this is I have.....(had) a
GSP Katana 140 with a Homelite 45 on it with Futaba servos S3010, and after
about 6 flights I devloped extreme flutter on the airlons. I was told it was
because the engine was not mounted with rubber and the vibration destroyed
the servos. I didn't notice any shaking on the ground ( except my knees ! ! )
but the servos have alot of play in them, I guess they just weren't strong
enough. Anybody have the same experience with these? The fuse is smashed
up to the canopy but the wings are o.k.!! Anyone need katana wings? I'll
throw in the servos!!!

Craig

Craig
I sent you a PM.

Pete

Pete
I sent you one, sorry for the delay.....I'm computer stupid!!!!!
Craig

Ok with the consensus being hard mounts, do you try to mount the engine mounts to the firewall as wide or as narrow as possible. I have seen threads both ways but I would think wider mounted engine mounts would spread the weight out and help with vibration. Any thoughts?

None here..........boy that was a good straight line if I ever heard one......................

I have never noticed a difference, I usually do mount mine wide though.