400 Connundrum

[scoot439]

I have a 400 that I aquired in a failed project that I bought right and put in my Demon. The problem is that when it gets up to operating temperature it 1) starts having a noise from the middle of the motor sounding like a bad waterpump bearing grinding and 2) the 40 PSI @ idle and 65 PSI @ 3500RPM goes to 10-15 PSI @ idle to 35 PSI @ 3500. There also doesn't seem to be getting enough oil to the rockers. I dumped the oil expecting to find metal, but found nothing but cam lube.
I have pulled the intake, valley pan and cam out expecting that the #4 cam bearing was suspect, but its fine. It has a mild Comp cam and lifters, 30W Valvoline and 6-7 heat cycles over about 3 hrs of run time. I'm running out of ideas. I've thought a bad oil pump relief valve might explain the oil pressure problem, but not the noise. Any other ides would be appreciated.

 

[demon seed]

Are you running a factory oil pump or high volume. If it's HV your pressure for a new build is way low and if it's a stock pump it's a little low. I'd drop the pan and check all the main and rod bearings especially the thrust.

Terry

 

[green1]

Thrust bearing? Try moving the crank

 

[scoot439]

Stock pump and thrust play is barely noticeable. This was a new motor that was part of a project that I bought for about .20 in the $. When I swapped pans I checked the bottom end clearances and they were .002 and the cylinder walls looked freshly honed so I'm sure the bottom end isn't the problem.
One thing kind of nagging at me is the lifters. These Comp lifters (on left) is noticeably different than the old MP one the right. I wonder if this could be the problem?