Bill You'll no doubt want to pelt me with rocks or something for being a total nit-picking smart ass after this :) Because it uses rockers the PRV is (strictly speaking) a "cam in head" design. A true OHC should operate directly on the valves, via bucket tappets or somesuch. Cheers Steve Abbott --- In dmcnews@xxxxxxxxxxxxxxx, "content22207" <brobertson@xxxx> wrote: > One correction after re-reading the original post: > >PRV heads are conventional construction, albeit overhead cam rather > than overhead valve. > > Bill Robertson > #5939 >