Dennis, I think I have a pretty solid answer to your question. In fact, it was right under my nose. Just had to put 2 and 2 together.
Attached is a copy of the program for my club's very first model contest. The Club was formed in February 1947 and ran the meet in August. All of the then current AMA Speed Records are listed on the cover. This meet and the 1947 Minneapolis AMA Nationals ran on the same dates. Ray Arden only started handing out glow plugs at the NATS and didn't actually start advertising and selling until September. So the records listed are all ignition era. Based on these speeds fuel was coming. One of the "transition" fuel blends I found was 35% white gas, 25% castor oil, 20% nitroethane, 10% ether, and 10% turpentine. After the plug began to be widely distributed fuel consisting of 3 parts methanol, 2 parts castor oil, and 3 parts nitromethane was kind of the standard.
Just a couple more details to put things in perspective. Jim Walker started selling the Fireball in late 1939 or early 1940. Line control was not written into the AMA Competition Regulations until 1944. There were Speed classes and Stunt. Harold DeBolt set a C Speed record of 95 mph with a Super Cyclone powered Speedwagon. For 1946 the rules were changed and for some reason Speed ended up with six classes. It apparently was not a popular change so clubs like the Buzzards combined classes and only ran four. I think the change only lasted a couple of years and reverted back. The other thing about the first rules was the requirement for a minimum wing area based on the engine size. As a result the first Speedwagon had a 200 sq. in. wing. That quickly went away also.
So, the glow plug became firmly entrenched, engines started being cowled in, and Nitro was king. The next two game changers were mag pans and Mono-Line. But, that's for another day.
Topic: Last ignition engine speed records? (Read 225 times)