Several years ago I rigged up something pretty simple to check for where I was losing oil pressure. I pulled the timing chain cover off. I made a little plate that blocked off the passages at the front of the block, and rigged up something to connect a garden hose to the oil pressure sender port. Then I just hooked up the hose and turned on the water, leaving cam, crank, etc in place. I wasn't too worried about the water causing rust or anything because I was about to disassemble it all anyway. Come to think of it, I might have also blocked the mains by putting a little plastic wrap on the bearings and setting the crank back down on it. That kind of rings a bell, I bet I did that.
In my case I had a surprisingly large hemorrhage between the #1 cam journal and the bearing. I say surprising because the cam bearing wear didn't look too bad to my eyes, but it sure did leak like a muther. Not much water leaked from anywhere else. That experiment is what convinced me to start using better quality cam bearings and trying to use a cam with no groove on the #1 journal. It also led me to replacing just the #1 cam bearing the next time I saw some wear there (when I was swapping cams again), which then led to something like a 5 psi increase in idle oil pressure.
Another guy here in Houston had his machine shop do essentially the same experiment after losing 3 rebuilds, and they found a big leak between the block and the #1 cam bearing. They bored or honed his block and put in oversized cam bearings (no idea where they got those!) and he finally got a motor that lived.
It was a real easy test to set up. The little plate I made to block off the front of the block was real thin stuff, I just cut it out from some sheet metal, and used a little RTV when I bolted it on. It doesn't have to seal perfectly, though I think mine did.
John
Keep us posted..Thanks..
