After reading four pages, it's readily apparent what the rule was made for. It was to exclude the later-model engines, GM and Ford, that were introduced in 1960. (Yes, yes -- as 1960 models! Jeremy Schmidt did the initial drawings for GM for the 230 in 1953, coincidentally the last year of the Flathead Ford, unless you count France, and the fact he was in Germany and did it in metric, which means it could be excluded in Gas Coupe unless it had a flathead motorcycle engine which if early enough (say before 9 A.M.) get a 33-1/3% (or 25%?) discount on displacement. Early entries may allow that to move to 42%, and you can then move up in class because no one remembers how to take one apart any more and measure it (Tuesday only).