Lube Failure and Rocker damage

My 39 B has a 1941 (by casting date) CE motor in it. Upon teardown (2 frozen valves from water down the stack, bent pushrod too) it is obvious that there has been a lube failure in he upper end. The rocker shaft is scored and worn up to 1/16". The rocker bearings are worn and in some cases scored. The damage is worse in the front and lesser in the rear, as would be expected by the oil fed from the rear. Lifters were badly worn from lack of lube and will be refaced. Mains and cam bearings looked OK although some grit scoring on #1 main, had crank turned and will get all new bearings. I will inspect the pump but that does not appear to be the issue.

The rocker shaft and bearings are no longer available new, and most of the used ones are getting worn on the shaft and bearings. I could turn the shaft over and end to end but it would still have too much clearance in the bearings for proper lube control. My workaround looks like a piece of slide tubing, .745 OD, and brass fine finish bushings, .755 ID, pressed into the arms. Any other suggestions to prevent reoccurance? I don"t want to go into this again. Tractor is used sparingly, mowing and snow plowing mostly.

I"m wondering

sounds like a loss of oil as you said. Could be the pump, could be excessive clearance in pump/ relief that caused loss of pressure, or could be BAD FILTER.. A few years ago there were some bad filters made that caused the loss of pressure and problems as you have. Those filters were paper and high volumn filters instead of packed cotton, low flow... YOu may not know, but the lube system is very different than a car. Pump puts out a fixed volumn. 15% of that goes thru the compressed filter, cleand and dumped back to sump. 85% of the oil goes from the pump, down thru the cam shaft and distribute by spray to the bearings (and thru the copper line to the top end)... If you have a filter that is BAD and flows excess oil easily, then too much flow goes back to sump and not enough thru the cam and to the bearings. AS you can tell from the above, excess bearing clearances from years of use do not cause drop in pump pressure.

during the rebuild, make sure the end plates on the oil pump are smooth and not gouged. Sand smooth if needed. Make sure clearances are minimal. At startup, make sure you have about 15 psi pressure at the gauge. Make sure you have oil supply thru copper tube to the rocker arm. I think i would buy a "good or decent" rocker arm/ shaft setup off e-bay instead of shimming or copper bushings on the old part. If you reamed out the holes and made a new shaft .030 inch oversize, i might go along with that modification.

B,C, or CA arm will work

http://www.ebay.com/itm/VINTAGE-ALLIS-CHALMERS-CA-TRACTOR-ENGINE-ROCKER-ASSY-1952-/251045287277?pt=LH_DefaultDomain_0&hash=item3a7377156d
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or this one
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I have 3 "good" sets in my parts pile. All of them show shaft and rocker bushing wear to some degree. The bigger problem is the unavailability of rocker arm bushings - if they"re not tight to the shaft oil just runs out the end rather than lubing the shaft and being forced up the rocker to lube the valve and pushrod.

I figured a precision shaft and new brass (not Oillite) bushings, drilled to feed the upper rocker, would be better than another used part that"s already on the path of failure.

I actually thought of rerouting the oil line to feed the shaft directly but that still would leave the clearance problem, would have to flood the upper and starve the cam/mains to get adequate oilling.

Also, make sure the "spear" that stabs into the filter, as you put it on, is still there. Without it, you don't get much pressure!

i have rebuilt 3-4 different B motors and have seen shinny spots on the shaft and small wear on the rocker arms. Seems like it was only a couple thousandths. Maybe im lucky, but i just cleaned them up and reinstalled. Seemed to oil o.k. Some of it might be the end plates on teh pump itself. Smooth plates with very minimal clearance will increase the flow available to lube. As Dave said, the tube inside the filter is the "restrictor" that allows a small amount to blead off thru the filter. I think the tube has 1 or 2 of a 1/8 inch hole in the top. No tube or big hole will cause low flow / low pressure.