IH 2400, can't get oil to rocker arms

I have just rebuilt the gas engine on my IH 2400 tractor. It runs good but no oil gets to the rocker arms. I popped the head back off, spun the engine with the starter, and saw oil coming up the the port in the block. I blew out the holes in the head and the rocker arms and still couldn't get oil. Next I plugged the oil pressure relief valve and started the engine. The gauge went past 100 lbs. and pegged. Oil just barely dripped from the rocker arms. So I pulled the front head bolt where the oil port is, flipped the tower out of the way and blew air down the hole. With the side cover off I could feel air coming up out of the sump. Everything must be clear, right? I started the engine and still no oil. So today I built a top oiler for it, plumbing it into the tap where the line to the oil presure gauge goes. Must have put too many holes in the tubing I used for the oiler, I was pumping so much oil up there it couldn't drain fast enough and started running out of the vent tube. Tomorrow, if I find time, I can close off some of the holes in my home made oiler and probably make it work but I'd really like to find out what the real solution is. Any ideas? Thank you.

Not familiar with this engine, but some of them oil the top end through one of the cam bushings [2 holes]. If this is the case, are the holes correctly aligned?
Alternatively, did you use RTV sealant on any surfaces where it may be plugging an oil passage to the top end?

Not familiar with the 2400, but I suppose it is an industrial version of the 240. The 240 uses the C-123 engine. That engine gets oil to the rocker arms though the center stud that holds down the rocker arm assembly. The stud is drilled to deliver the oil from the pressure side. So maybe someone replaced the stud with one that is not drilled. That has happened and has been discussed before here on the forum. I had one tractor that had a bad center stud. Stud not available from IH as I recall. I had to get a stud from NAPA and drill it myself.

The 2400 is more like the 464. The oil comes up around the front stud. But thanks for trying to help. Rick

Didn't use RTV sealant. I like that copper spray gasket sealer I get from NAPA. The cam bearing theory sounds promising. I'll try to find out if that is how the oil is sent up through this model. The cam was installed at the machine shop, they said it required a tool I didn't have, and they are usually pretty good with this stuff. But anybody can screw up now and then. This probably means the cam bearing isn't getting oil either so my top oiler isn't going to do anything for that. I won't be able to get to it for a few days but this seems like the most likely approach. Thanks, Rick