Are the 65cc combustion chambers on Speedmaster and Promaxx heads closed or open like on the Edelbrock 340 head?
If they're both closed, is there any difference in the chamber design or is it more of a case of clever marketing of casting variations?
An Edelbrock head requires a lot of chamber work to get as good as a Speedmaster head. Both require work but the chamber on the Edelbrock head crowd the valves. Especially the intake valve.
