Finally stopped my engine vibration problem

Having built several Shoestrings, I have had nothing but vibration issues. I exclusively use the Fox .35 with these airframes. I have discovered that the Shoestring is prone to vibratory issues resulting in extreme vibrations that have broken glue joints and shook the lines all the way to the handle.This loses airspeed, rpm's and patience. I'm no stranger to the Fox .35 and I have dealt with pretty much every problem one could experience from using them. I have attempted to add weight to cranks, grind material from the piston. This plane which I recently built was essentially useless trying to run the Fox. The engine rpm's were so radical you could not hold the plane long enough to adjust the needle. I have done a shotgun blast through the entire engine pinpointing, adjusting, lapping and polishing you name it. My last attempt was placing 1/8" steel plates under the engine lugs and really cinching the engine down. That helped a bit but the engine runs were horrid and the flights were non flyable. It's very difficult to harm a Fox but after the dozens of burn down runs I gave it, I was pretty skeptical that I had done some damage to it. My buddy Dan Banjock however suggested that he wanted to try something a bit different on this. He made this spinner which internally has 3/32" ball bearings that run in a groove inside the spinner nut. I figured what the heck lets try it. Well today off to the field and I have to say it's a good thing that I didn't suggest eating my hat. This darn thing was amazing. It worked like a charm. Put it on and the engine needled well and flew well. Take it off and it was back to square one. We used some light silicone grease on the balls and flew this thing all day. This was indeed a very cool fix for something that wouldn't work. Dan saw something remotely like this in a ad from a 50's Air Trails magazine. He made it yesterday and I can't wait to do some more experimenting with this in terms of size, balls, weight etc.  You can't run uniflow on a plane that's foaming the fuel. My first tests were using the chicken hopper on standard vent which worked well. My last few flights were on uniflow which pretty much worked flawlessly with the exception of going lean immediately on launch. Necking down the pipe will fix that but I could also launch slightly richer.


 Here's a picture of the engine with the lugs padded underneath.

A common problem here on profiles is the vents become placed in turbulent air due to the cylinder head mounted profile. It's very imperative to get the vent into clean air. For now I just extended the vent using a piece of fuel tubing to fly it. It will be hard piped into my engine cowling next.

Back of spinner nut
ball race side of spinner.

       All I can say is it works and I couldn't be happier. Ken