After having my heads rebuilt with new valves I've had two problems crop up after about 500 miles with no issues. The first problem was that RPMs started occasionally randomly drop when at idle, potentially causing a stall if I didn't attempt to use the gas to keep the revs up. The next time I took it out I noticed an unusual slight ticking sound and had to park it.

I pulled the valve covers and at first didn't see any issues, but then noticed that edge of at least 3 of the spring retainers had small indentations. All of them looked like they were very close to making contact in the same way. Prior to the rebuild I had been running the same valve/spring setup with the stock rockers with no clearance issues. My theory is that the grind for the new valves lowered the seat just enough to allow the valve and spring to come up high enough to cause a clearance issue with the stock rocker arms.

Aftermarket rocker arms seem to be on the more expensive side of things and I'm not looking to do anything but deal with the clearance issue. I recall seeing something on the board about someone removing a slight amount of material from the rocker arms (but cannot find it with the search tool). In my case I would need to remove about 1mm from the thickest part of the arm. Had anyone does this, or heard about successes or failures as a result? Will any modification to a part such as this do any more than just proportionally reduce the strength of the part?

 

One other option would be to put spacers underneath the rail that the rockers mount on. This would make the push rods effectively shorter, but the increased height of the spring already requires a shorter push rod when the valve is fully closed. Moving up the pivot of the rocker arm should help even the even the angle and get things back to clearing.

Come to think of it there must be some small amount play in the lifters when the valve is fully closed. If there wasn't you would risk not allowing the valve to completely close. If this is true then moving up my rocker might actually bring me closer to my original lift numbers (right now I probably have more lift than before) Can someone who understands this comment on my ideas?

 

I know that Cartek Performance Engineering has had great success working with/fabricating both stock and aftermarket rockers as used with various cylinder head combinations, maybe give them a call.
908-317-4496
www.cartek.net