Dennis,
This is the other Eric that I think you were referring your question to. I was attempting to build and fly this class back in around 1998 when I saw an article or message by Eric Williams about the planes. I had a couple of Fox 35 stunt engines and had become sort of disenchanted with them as a stunt engine so when I saw this speed event I thought I would try my hand at it. I cant remember all of the rules but one was a stock Fox muffler, another was 10 percent fuel, exterior bell crank, at least one wheel landing gear. The engine had to be all Fox 35 stunt but you could modify the Fox parts anyway you wanted to. Not being much of an engine man and no machine shop experience I only modified the crank by enlarging the size of the induction port, opening the crank case intake port size as much as I could with out grinding through it, and carefully polishing everything to get rid of any stress marks left by my Dremel tool. I cant remember what prop I used but tried quite a few probably in the 8/6 or 7 and 9/6 or 7 size.
You could build any type of plane as long as the engine wasn't cowled in, it had to be a profile. I had flown quite a bit of Rat back in the early 60s so that was the type of plane I used. The best I ever did in speed was around 95+/- mph. The Swan brothers who lived in Clovis CA also, saw me flying my plane so they built one to and they were turning over a 100 mph which I could never reach. The engine failures that I experienced were the pistons breaking in the area of the pin which may have been caused by not enough break in time. I know I had a lot of crackling which I thought was pre-ignition and I cant remember whether I tried adding head gaskets. I think the Swans just got tired of messing with the Fox 35 and concentrated on flying stunt. Bob Swan is still flying stunt in the central valley in CA. Eric