I'm new here and figure my question has been asked a million times, so I apologize. We run a 302 cu in (010 casting 350 w/4-blt mains, .60 over bore, forged 3" stroke crank, 6.125" rods, comp cams .535" lift cam, "906" Vortec heads, comp cams bee hive springs, chrome moly push rods, guide plates, screw in studs, comp cams stamped steel roller tip rockers, enlarged push rod holes) in a modified dirt track car. We've run this engine in about 20 races so far with no problems to speak of until now. Since the heads were professionally prepared, we didn't do much other than check the push rod length and set the lash. The engine turns 7800rpm and will probably do even more. First problem noticed was valve spring shims being broken and squeezed out from under the springs. While investigating this we discovered the roller tips don't seem to line up with the valve tips when in the open(ing) position. Everything I have ever read about these heads and rocker arms is to use self aligning rockers and no guide plates or guide plates and regular rockers. What really brought it to our attention was when we tried to fit aluminum roller tip rockers with a trunion mount on stud. The rockers will not line up with the valve even with no locking nut installed. What shall we, can we, do? What causes the shims to break? This engine has been running like a scalded cat and holds its own with much larger engines with 4 bbl carbs.
It sounds to me like the valve springs are bouncing off their seats causing the spring to spin, and then the valve is not being controlled by the spring any-more. I haven't had much experience with Bee-Hive valve springs at high RPM. One other thing comes to mind. Are the valve spring pockets much bigger then the valve spring? If they are this could also cause the valve spring to spin and move around and cause your shims to crack. Check the key ways for excessive wear. When a valve spring bounces uncontrollably it beats the key ways to death. Then you can drop a valve. I'm sure your using at least 7* or 10* retainers and locks. But it can still happen...Good Luck and let us know what you find.Bob