Reworking the 273 Adjustable Rockers
I guess I'm not sure I understand the need for this mod. At no time do the rockers get "full oil pressure" unless you change the method of oiling the top end. In factory oiling the holes line up to expose the shaft to operating pressure for a few degrees out of 360°. I'm guessing something like 15-20°? So what's felt is a pulse which is then dispersed over the whole shaft because the oil pressure is leaking out the shaft and the sides of each rocker.
I wouldn't use these rockers for "big springs" or "big rpm". And if I was building for those, I'd probably be swapping to pushrod oiling.
I have run this type of rocker with 280 on the seat and 750 over the nose. It is the W-2 rockers but other than the bushing, they are the same.
Once you get past about 2500 RPM, there is almost constant flow to the rocker shafts, because the time spent with the holes lined up is short. There are pulses for sure, but as the RPM's go up, the pulses get shorter. As long as there is pressure in the system, when the oil hole in the shaft and the oil hole in the rocker lines up with the hole in the shaft, it will pressure feed the cup and ball with full oil pressure. That is another reason to run a HIGH VOLUME, HIGH PRESSURE PUMP. You need all the volume you can get, and the pressure helps get the oil out of the shaft to the cup and ball.
I have successfully run 360 pounds on the seat, almost 900 over the nose and made power past 8500 RPM. And almost never hurt a pushrod. It cost me almost 20k dollars and several years but I got it. With ZERO help fro MoPar. I actually had a lawyer draw up a bill with documentation and pictures of the issues, and how (at that time) brand new rockershafts were incorrectly drilled. They used the "race only" clause to screw me but all I really wanted was a PUBLIC tech bulletin acknowledging the issue and the correction for it. But they don't care.
Most guys don't need pushrod oiling.
I was at PRI about a 15-18 years ago and I happened by the Jesel booth. There was well known engine builder there who I met in person a couple of times, and talked to him on the phone many, many times. After we all were introduced, I was let in on the conversation. And the discussion was how to ELIMINATE pushrod oiling in Comp and Pro Stock engines and trying to use a system (highly modified) that was close to what Chrysler had used. Those guys don't care for PR oiling but they are better with the devil they know.
AFAIK, they looked into the non pushrod oiling deal, but not sure what came of it. It's possible the whole thing was not worth the effort.
EDIT: I also wanted to mention that most of the time, in situations noted above, I put a fairly big groove in the number 2 and 4 cam bearing journals. This helps, especially over 8000 RPM to keep oil upstairs.
