I am having what an odd oil pressure problem with my 350. It is a marine application, with vortech heads and a hydraulic cam. It’s the standard marine set up rated at 300 hp. I am not sure of the cam specs but do know the engine was dynoed with the cam and made 300 hp with no symptoms. I had the engine rebuilt two summers ago(rings, bearings, pistons, gaskets) and have about 80 hours on it since rebuild. At idle I have 40 lbs of pressure, under power at 4,000 rpm and at operating temperature I usually have 50 lbs – 60 lbs. At some point during operation I lose nearly all oil pressure, drops down to 2 -3 pounds. I have an electric oil pressure sender and have removed my electrical sender and used a mechanical gauge to confirm oil pressure. The mechanical and electric readings were within a couple of pounds of pressure. I initially thought I had a bad oil filter and changed the filter. After changing the filter the oil pressure returned. I again used the boat and had the same symptom reappear after only an hour or less of use. I limped back to the dock showing 2-3 lbs of oil pressure. The engine was running fine otherwise, no misses or backfiring, so I don’t think the problem was or is in the distributor gear. As soon as I tied up at the dock I changed the filter again and started the engine. With the new filter oil pressure returned. I used the boat again this weekend for about an hour and was under full power for quite a while and kept a close eye on the oil pressure. I was turning about 4,000 rpm and had about 50 lbs at operating temperature, 160 degrees. As soon as I powered down to cruise in the oil pressure dropped to nearly zero. I turned the boat off and let it sit for 10 minutes. On restart I had 25 -30 lbs. I don’t understand how I can have an intermittent oil pressure problem which seems to be centered around the oil filter. I have tried several different brands and each, Wix, AutoZone, NAPA have produced the same results. We cut open a couple of the old filters and saw some of the pleats leaning on one another but generally the filter media looked ok and not visually collapsed. I changed the oil and filter right before the most recent problem. The oil is still clear and looks visual fine.

Is it possible I have a problem with my oil pump or should I be looking elsewhere? If elsewhere, where? Is it possible I have a bearing problem? If a bearing problem how can that be exhibiting the symptoms I describe?