I would be a bit suspicious of the pump pressure relief valve, it may be stuck open. I would also replace the oil filter before any more testing just cause of the low money and ease of doing it. Pre oil the filter of course.

GOOD TO SEE that certain are FILTERING OUT excessive usage of smilies

I guess that the charge of 1$ EACH for the over usage of 5 per post is being followed !!

Could it have snapped the pump drive hex off with the 20/50?

It’s a fresh rebuild on my ‘70 440. When I got it back, on cold start the pressure goes up between 80-90 PSI, then slowly drops as the oil warms. And once fully warm the pressure never got higher than around 43 PSI no matter the RPM & at idle it would drop to around 13 PSI. These were mechanical gauge readings but the factory electrical gauge was similar. Slower to respond but similar readings. I replaced the mechanical gauge with a new Autometer gauge with same results. This was with 10w40 oil, the engine builder, a relative, suggested trying 20w50, which I was skeptical of but tried it anyway. With the engine pre-warmed & the 20w50 warmed to room temperature I got ZERO pressure! I let it run just long enough to know that the pressure wasn’t moving either needle. He then suggested undoing the coil wire & cranking the engine to look for pressure ( a practice that I have since read is taboo). Again, zero pressure.

Unless some of you have better advice my next plan is to manually spin the pump & see what the pressure does, although since it won’t be getting warm I have to question whether I can get an accurate idea from this method. Opinions on that?

My presumption is that it’s a weak pump but it’s a new one, so....... Again, opinions? My engine builder is eight hours away so it’s not convenient to take it back or have him come to me so I need to try & figure this out myself. But before I pull the distributor & intermediate shaft out I would like some wiser heads than mine to weigh in. Wondering whether to just replace the pump before any other action or proceed with manually checking for pressure?

Any thoughts would be greatly appreciated.

Thanks.

If you bent a pushrod and threw a lifter out of it's bore you will lose all oil pressure. Pull both valve covers and make sure all the pushrods and lifters are in place.

I had that happen to me, I think I torqued down the rocker shaft too quickly on a filled lifter. Not like I was winging it up to high RPM or anything, heck I was leaving the doctor's office with my daughter when I lost oil pressure.

I also had a very small chunk of casting flash break off in a 360 and get caught up in the oil pump, locked it up and snapped the end off the drive. Not even sure how it made it past the pickup screen.