Greg Dillon
Active Member
I don't know if this is common knowledge but I'll share this bit of info for those of us using this engine. I'm overhauling an H2AD for my RV9A-so far the expensive parts(other than the cam and 2 lifters) are still at new specs-crank, rods, case halves. I was cleaning the valve gear parts at work (I'm a diesel mech) and one of the foremen noticed that the rocker arms looked like Ford 351 C parts. My wife works at an auto parts jobber store so I asked her to bring home a new rocker arm and pedestal for a Ford 351 C --lo and behold the parts were identical . In fact the aftermarket (Sealed Power) rocker arm looked better! So I ck'd the Ford Motorsports website and found that aluminum roller rocker arms can be had that will bolt up with no mods to 351 C heads. I'll be getting a pair of these to test fit-if they work out they could possibly reduce valve guide wear due to less scrubbing action putting side loads on the valves. The big question is whether they will fit under Lycoming valve covers. If not the Sealed Power rocker arms would be a much lower cost replacement for the $25 ea. Lycoming branded rockers. Looks like Lycoming used their head and went with a proven part from a car engine with untold millions in use for their aircraft powerplant. Now if I could just find out who made the lifters for them($160 each ) I had the undamaged lifters refaced by a machine shop that wasn't afraid of 'Aircraft Engine' parts. Not so with the cam-the welding shop freaked when they saw it was a Lycoming cam--oh well-anybody have a yellow tagged cam for an H2AD? Greg RV9A N4603X (res) (EFI)0-320-H2AD