ring Mount on a Model IV?

[Wheels]

Has anyone ever put a ring mount on a model IV?
I am going to install a new 80HP Rotax 912 and am considering the advantage or not of the ring mount. Looks like a lot of work and modification and I want to be sure its a good idea.
Any input from experience or guesstamation will be helpful.

[HighWing]

I put a ring mount on my 1992 version Model IV. My intention was to get the baggage sack capacity I lost when I put all the ribs and fairings on the tail of my first IV. Then I had to placard the baggage sack to max 20 lbs. This time, the empennage was even heavier as I had servo controlled trim on both rudder and elevator plus all the ribs, gap seals and fairings as on the first one. I kept pretty good records on the weights I added with the mods this time and figured it to be about 6.5 lbs. at the eleven foot arm. I calculated about two inches forward on the engine CG would give me what I needed. A significant side benefit was the ability to place the oil tank in a more favorable position vertically.

I think the CG might be the major issue. As my intention was to move the engine forward I didn't consider the geometry of doing it at the same arm especially because my intent also included a repositioning of the oil tank. I should also mention, that my ring mount was 100% home brew.

This shows the right side with the oil tank mount aft and below the exhaust stack
11205

The left side with a clear view of the ignition module bracket
11204

The ring mount fuselage side.
11203

The isolator set-up
11201

The custom home brew rubber isolators
11202

[mr bill]

I wish I had seen these mods in time.

[Av8r3400]

You're my hero, Lowell… :o

How much did you have to mod the cowling?

[HighWing]

Hero? I see things done by guys - you included - that fit that description, but me, i think i am more addicted to tinkering than anything else. The cowling was an expected project. I added about two inches to the aft edge of the bubble cowl. But the unexpected part was when I fitted the aft cowl and found that the repositioned oil tank interfered near the bottom. My engine was a used engine and the oil tank had some slight denting at the lower edges so I assumed it was made from an annealed stainless steel, so that problem was managed by doing some body work on the lower edge with a hammer. The hammering worked well, but looked really rough, so some micro and a coat of paint took care of that. I probably have the only painted oil tank in the fleet and it was to cover an unintended glitch.