Loose engine again.

The Pathfinder that had brass inserts instead of "T" nuts to hold the engine down got removed and I made an aluminum plate that held the enigne and was screwed to the wood motor mounts. Even though I used 6 screws to hold the thing to the plane it again loosened after several flights. I considered several fixes and bit the bullet and drilled through the nose. I replaced the bolts that held the engine to the plane with 4-40 bolts and nylon insert lock nuts with a jamb nut on top of that.I drilled through the plate and the wood motor mounts and cut away the balsa on the other side of the fuselage so I could put more lock nuts on the other 4-40 bolts. I flew it this morning and things went well. Except for some dirt that got through the filter and into the spray bar causiing a lean condition. That ws cleaned up quickly. Yesterday, along with the Pathfinder, another of my designs had lean engine run. That was on the ground and I stopped the engine and went home. I found a piece of dirt that came out with the needle valve. There isn't enough room to put a filter in the fuel line inside the plane so I decieded to run the fuel line outside the fuselage with a filter in the line there. I flew that one too this morning and it went well also. The fuel filters I use are take apart to clean and some how I lost the filter screen in one of them. That one has been in the parts box for a while now. I asked about filter material on a forum and got a good answer. As it happens I bought a reusale coffee filter year ago and use it to fliter my fuel when I make a batch. The answer I got reminded me of the filter and I used a paper punch to get a usable filter piece. I fit right in and I installed the filter on one of the other planes. The new Pathfinder is coming along and I'm finishing the wing now. Lots of sanding and then covering with paper and dope. I have to do some work to the nose area so it blends with the prop spinner. Good old trusty "T" nuts on this one.