wrench87 I had used 1 set of cork gaskets for 14 years. This is too long, 10 years is fine. My gaskets where glued to the valve covers and a small spot of sealer to the spot where the intake manifold and heads meet. Nothing else. IMO and racing with Erson rockers for 7 years, .080" oriface is a safe size. I have seen .060" and blueing of the pushrods and cups of the rockers them selves. How much
oil in the heads is not just about the rockers. There is alot of heat produced from the valve springs going up and down at 200-400 cycles per minute and this is low rpms. I flood my heads to the bottom of the pushrod holes. I have had no failures or blueing. If you are using pushrod oiling than .060" would be ok for rockers.
The limit on the cork gaskets was push beyond normal and did cause a small
oil fire at Hasteings race track. No damage to car, only 1 wire was repaired. I would still run cork over rubber because of the height differents at the intake to head location.
If you are getting leaks from valve covers or any gasket that is under a low pressure area of 2-4 psi like valve covers, I would take a pressure reading to findout what is going on inside the motor. Start with the PCV valve first and check breathers in valve covers. Too much blowby of the rings could cause leaks, have seen this with the new low tension rings and not using the power to help seal them and breakin on the cylinders. Any other questions, ask and blame Jim. Rick L.