I use these with zero problems ever. How big is your oil pan,does it need to be hot to screw up? I'm running a 14 qt off shore pan and -12 hoses. When I ran stock hdwr and a stock pan my motor would carry 60 psi and drop to 45 at wot after a few minutes but it sounds like your problem may be more sudden or does it intstantly,Smitty

I actually saw a 15 psi increase on my old 502 from just changing everything to bigger stuff without even getting into the motor so even though the new/bigger parts can't "create oil pressure" the stock size fittings OR ANY ONE FITTING THAT CAUSES A RESTRICTION can definately reduce oil pressure. I would assume the pump bypass is forced open from too much restriction in the hoses and reduces available gpm's of oil to the system. I have been told my oil system is overkill but I used all-12 hose and even used full flow fittings at every turn and limited the amounts of steep bends any where I could. Anywhere you had the choice between a 90 degree adapter and a straight adapter with a 90 degree full flow hose end I used the hose end,Smitty

Another question-did your motor always do this since built or is it something that started happening afte x number of hours of run time. You mention 15 hours of run time,were you able to hold it at wot BEFORE 15 hours and it held 60 psi? Did you change the oil pump when you had it back apart to check the bearings. Re-reading everything I would think if everything was fine at one time and you verified all the clearences are still the same and nothing was damaged that your oil pump bypass is now opening or more oil is going thru your lifters or something. Was there any other changed along the way or is your oil running hotter? Did you give it more timing at one point?Smitty

Thats what Im using.

I started losing oil pressure under acceleration after I tested a set of props. I ran the motors up to 6000 rpm, after that I noticed the oil pressure dropping. The other motor is identical and has no issues.

I have a hp 500 cooler and I do have a stock adapter at the block. The outlet side has been drilled out and I run -10 lines. I do have a 90 in the outlet. My second motor is pumped the same with no issues.

Just a thought, did you check the distance from the bottom of the pickup to the pan floor... I was directed that way once, so it seems it is important..

Dick

Not to beat a dead horse but I to had the exact same scenario, lost pressure with increased rpm, changed filter and sender, took care of
it, sure it was the filter.

Tried hp4 filters, guess with my luck I could of got 2 bad ones.

3/8 from bottom.