OK, I've been busy the last couple of months with motorcycle stuff, bike week, a number of other trips etc... Finally getting back to stage 2 for the little GLH. I did send one of the motors to Bob Mattes and got it back a while ago. Ordered up some Merlin drop ins for it and finally got a chance to run it this week.
First I have to say Bob's work is excellent. He not only custom built the head, but shimmed the bottom and top of the cylinder to get the port timing correct. The backplate mount is a real nice piece of machine work as well. I had sent him a stock venturi as well as one I had opened up, which he chose to work with. He also added a brass thrust washer behind the drive plate to reduce wear when using an electric starter and included a nice, larger spinner that is machined to fit inside the hole in the APC props, eliminating the need for bushings or fuel line to take up the slack. As a last touch he installed a machined ring over the plastic where the venturi bolts on to keep it from splitting. He then ran the motor with an APC 4.2X2 and sent me the specs both with the Merlin head and the Nelson. He recorded 25600 on 40% and said expect 2k more with 60%. Not bad.
So the first thing I did was enlarge the prop slightly to fit the spinner. The first run on the bench with a 4X2.75 gave me a bit over 22k. I then ran one I had trimmed another 1/4 inch from BUT also remounted the engine to the stand as I had noticed some vibration just mounting it with 2 small wood screws. A tip for anyone using the TD 020 motors- make sure your firewall is perfectly flat and use BOLTS, not screws. This I had done on the motor currently on the plane and it makes all the difference in the world. The next run gave me 26900 on the bench using just 35%! And this is on a motor setup to run 40-65%. I am also using little red caps for bladders as Bob recomended and can say they give very consistant runs. Next step will be mounting on the plane and finding space for the bladder.
