35fountain

Not a good weekend for me, First a power steering pump and now a broken pushrod ball...I heard a loud tapping noise while just getting off of plane. Remove cover and noticed # 3 exhaust valve rocker very loose. Remove rocker and the little ball fell out in my hand. WOW lucky it didn't fall into the motor. I just installed these rockers 3 weeks ago because they got hot and changed to a burnt color from using the wrong chrome valve cover last summer. I put on covers without drip rails and the rockers were starving for oil at high rpm's. The rockers are comp cams steel with roller tips. I set lash @ 0 and the 1/2 turn more with the Mercruiser adjustment sequence. example : TDC firing #1 you can adjust rockers 1 int 1 ex etc.. then turn 180 degrees firing at # 6 and adjust rockers on another bunch of cylinders. Installed a new pushrod today.. set lash @ 0 and 1/2 turn more.. replace valve cover.. sounded quiet. Cruising at 3200 rpms and when I got back to my home port A rocker tap again. Not sure yet if it was the same one.
I decided to replace all pushrods, arp studs and locking nuts.. What is causing these rockers to loosen @ 3000-3500 rpms.. rockers, balls, nuts are new except for the pushrods that may have gotten hot from the no oiling issue. Engines are twin 509 490 HP Dyno mild crane cam 531 lift 236 duration, emi exhaust msd ignition locked out at 34 degrees. I have this boat 5 years. It originally came with regular stamped steel rockers. I upgraded to the roller tipped when I did a valve job last year.
Any help would be appreciated