I have a 572R I purchased new and have run it in my race car trouble free for three years. The oil pressure stayed on zero the last time I cranked it. I have tried three gauges, all zero. It goes to 20 psi when first fired up, but only for 1-2 seconds and then zero. It normally runs 70 psi at 1400 RPM. Does anyone know where I can get an oil flow diagram for this motor, or any late model big block Chevy? Any ideas?