Ted,



Could you elaborate re: your reasoning for NOT pressurizing the shafts? (In my case, I was always afraid that oil would flood the valves if not directed straight down the pushrod/drain holes).



Michael,



Do you know the ID of the smaller drain tubes you installed?

6 VOLTS/POS. GRD. NW INDIANA

This is what I did on one of my motors. When doing a valve adjustment and valve cover replacement. A friend of mine that has/builds all kinds of motors suggested that I take the rocker shaft return line and pinch it down to pressurize the rocker arms. Well what I ended up doing was accually reducing down the return line with a much smaller one so it somewhat pressurized the rocker arms. I had very good oil pressure before, like 30-32 lbs at idle. After that it went up to like 40-42 lbs. I was really surprised what a differencce it made and how much quieter the motor  was, but I suppose the adjustment helped a heck of a lot too.

                                           Michael

Michael

Sandy Valley, NV

Here's my two cents worth.

 

I have drilled the additional oiling holes in the valley only to be surprised how much oil is actually thrown up out of those holes under full throttle.  I had a clear cover over the valley while dyno testing which permitted me to observe what was happening in this area under throttle.  There’s obviously enough oil to the camshaft without the additional oil holes in the valley but there is some crankcase pressure relief taking place which would allow oil to flow to the back of the block easier and drain to the crankcase via that route.  Without the additional holes, the only pressure relief from the crankcase is happening from the two small holes at the front of the block and the distributor hole cavity.

 

Although I haven’t seen it happen, the potential for cracking a block down its middle is intensified in a high horsepower application when drilling the valley with a multitude of small holes.

 

I’m also in favor of grooving the block in the center cam journal so that the three oil holes are interconnected.  The cam bearing then just presses in place over this modification.  At this point, it’s just a simple matter of putting a restrictor in the rocker arm pedestal to control the amount of oil going to the rockers.  On the race engines, I’ve experimented with as small as 0.062” while on street drivers I’ve had this restrictor as large as 0.110”.  I still use the oil drain back tubes on the shafts to allow the oil to free flow through the system rather than pinch off or block the tubes and pressurize the shafts.

Lorena, Texas (South of Waco)

I'm curious what the current general consensus is re: pressurizing the rocker shafts, and drilling/grooving the block valley. I've heard a lot of pros & cons over the years, and wonder what the pro builders do for a street motor? (Verne Schumann is a fanatic about both). Worth the trouble?

6 VOLTS/POS. GRD. NW INDIANA