I suspect these rocker arms are a victim of ZPS (zero pressure syndrome).

How’s this bearing look?  It was a self-inflicted wound.  Who would have thought that a main bearing gets its lubrication from the cam lobes.

Have any of you seen bronze deposits on your clutch spacer?  I’ve had trouble with a grabby clutch that squeals.  I have since corrected those problems by restoring the wave washer assembly, but while figuring out the problem I noted that my push piece o-ring seemed to affect the squealing problem.  When the o-ring wore out, the problem got worse.  Something tells me that the clutch could use a little more oil too.

My engine had reached the point where the power was just too much for the stock lubrication system to keep up with.  What the heck, the stock oil system can’t even keep up with a stock engine, why did I expect it to provide sufficient lubrication for a modified engine?   I also managed to shoot myself in the foot by installing a DR cam without drilling holes in the cam lobes.  Obviously, I did not fully understand the system.  It was time to take a hard look and see what I could figure out.

With engine oil at normal operating temperature (about 200°F), my oil pressure was always “zero” at 1300 rpm (idle), and about 6 to 7 psi at 4000 rpm (freeway cruise).  That’s with 20W–50 Mobil 1.  If you run 10W-40, you can expect less pressure (how do you get less than “zero”?).  As you can see, the stock oil system doesn’t develop a lot of oil pressure.

This is a schematic of the stock system.  There are three main circuits: bottom end, top end, and transmission.  Note that the main bearings are not pressure fed, they get the leftovers.

The pump is driven by a set of gears.  The pump gear is rotated by a drive gear attached to the clutch basket.  As the clutch basket rotates it turns the oil pump.  The diameter of the gear on the clutch basket (30 teeth) is smaller than the diameter of the gear on the pump (35 teeth), so the pump turns slower than the clutch (0.86:1).

A view from the outside of the engine case shows the location of the various oil circuits.  I grabbed this photo from someone else’s old post.  Can’t remember who posted it, but they did a nice job.  Whoever you are, thanks very much.

You can see from this excellent markup, that the stock system has three flow circuits, bottom end, top end, and transmission.  Don’t be fooled by the description “to tranny”.  Yes, the oil in this circuit goes to the transmission (also to the clutch), but it doesn’t lubricate the gear mesh.  It lubricates the idler bearings inside the gears.

The filter is housed in the clutch cover, so the oil supply to the filter runs directly into the clutch cover.   The oil supply out of the filter is directed into the end of the crankshaft to supply oil to the bottom end, and into the channel that runs fore & aft along the top of the engine case, where it connects to passages that supply the top end and the transmission.  There is a .071” orifice in the transmission supply.

It has this cool plug (green arrow) at the end of the main oil passage.  That plug presents all sorts of possibilities for measuring pressure, hooking up a cooler, supplying oil to specific components, etc.  I like that plug.  But remember, this is a crude lubrication system.  If you take oil from that passage, you will be robbing oil from the other circuits.  Oil pressure will diminish rapidly because you will be adding a 4th circuit.

The .071” orifice in the transmission oil circuit looks inviting too.  Make the orifice bigger and maybe you can help the gears.  Same problem.  If you start messing around with that orifice, oil pressure will change.  Make the orifice bigger and pressure will go up in the transmission, but down at the bottom end & the top end.

Oil enters the filter housing and surrounds the pleated filter cartridge.  The port circled in red is where the oil comes into the filter cavity.  The port circled in green is where the oil exits the filter and branches out into the three separate circuits.   The small hole circled in yellow is not an oil passage.  It is a threaded hole used to mount an oil seal retaining plate on the inside of the clutch cover.