lots of good replies and info. I do have to differ on a couple of the posts or at least add my nickles worth (inflation). One mentioned RPM's 7500, keep in mind thats the crank, cams turn at half that. Cars and trucks don't use them? well I've been pulling apart the latest and greatest V6's and about half have over head cams with roller rockers. It's only time before this consept migrates into the V8's. There are a few out there all ready Toyota for one. No worries about breaking the studs then. Oh and then add in the variable valve timing features, now your moving into a down sized engine with the same HP. Throw in some direct inject and you get a few more gains in efficency and HP --- best of both worlds.

Rockers
 

Joe you made much sense and I couldn't agree more. I think with the rollers reducing the side loading on the valve stems, thereby reducing friction and perhaps heat is enough of a reason. That said with the higher lift cams they can certainly be put to good use. As far as any HP goes I would say there are very little gains provided the geometry is correct in both applications. I'll let you guys know this week on a 540.

I do know one thing for sure and that is I wish I was the one who invented them. Was that - Harland Sharp???

John

My .02 is that I have always been told that the weakest link on a BBC is the valve train. That being considered, the "stud mounted" rocker arm system be it stamped steel or roller rockers is technology from the 1960's. The better designed rocker arm system is the "shaft mount" system such as a Jesel or T&D type. The shaft mount eliminates the need for studs, pushrod guide plates, and in some applications stud girdles. So in some cases the shaft mount system is not always that much more expensive than the stud mount system that requires those extra components.

Shaft mounted rocker
 

No debate there what so ever, shafts are better.

the number one reason for them is the valve train in a boat take a beating and are the weak link why do you think sterling engines changes them like socks stock or full blown race motors they are weel wodth the money my 3 cents worth