Ford used retarded camshaft timing for God knows what reason. If you read up on the history of it, some say emissions, some say to reduce cylinder pressure to aid in reducing spark knock. This was certainly true of the spark knock plagued 400 Ford engine. They used the 351C open chamber 2 barrel heads on it. Ford kept trying to reduce the cylinder pressure through dishing the pistons and retarding camshaft timing. Little was known then about quench as compared to now. Had someone had the bright idea to try the 351C 4V closed chamber heads on the 400, that would have solved the problem with quench......and made a 400 monster at the same time. That engine suffered from spark knock issues though, right to its demise in 1982.