The AMA Grand National Championship Class C rules, introduced in 1933 and revised in 1954, had an equivalency formula limiting side valve, engines to 750 cc displacement, while more modern overhead valve engines could be a maximum of only 500 cc.
Over time, this displacement advantage kept the older side valve technology on the track and discouraged a broader field of competitors.
At least ...
- 0
- 12 Oct 2024