427 BB Chevy oil pressure problem

[ParkerSteve]

Hi gear heads, put them togeather on this.. New to me 427 BB has a issue. At WOT my oil pressure drops to about 35-40 psi and I get heavy oil mist and oil droplets out of my valve cover breather. lower the rpm and oil pressure back to 55-60 psi and misting stops. I'm thinking oil is collecting in valve train area, not getting back to 10 qt pan as quickly as needed. What do you think and what would be the fix, :idea:

[Dragboats]

Hi gear heads, put them togeather on this.. New to me 427 BB has a issue. At WOT my oil pressure drops to about 35-40 psi and I get heavy oil mist and oil droplets out of my valve cover breather. lower the rpm and oil pressure back to 55-60 psi and misting stops. I'm thinking oil is collecting in valve train area, not getting back to 10 qt pan as quickly as needed. What do you think and what would be the fix, :idea:
Could be several things, sometimes it gets tricky finding the problem. What pan do you have? Could be lifter bores worn, crack in pickup which is comon on the milodon standard pick. The extreme marine one helps. I have seen some guys run a # 10 or bigger line from the fuel pump plate to the lowest point in the valve cover to allow oil back the pan faster. Try lowering the oil one quart at a time and see if that helps. sometimes to much oil in the pan and the crank will airate/whip the oil and keep it away from the pickup. Pickup clearance is also a potencial problem. Thats the short list, try lowering the oil level first, then start tearing stuff apart.... Do you have pan evacs? do you have baffels in the v cover breathers?..........

[alien2]

I agree that the crank is probably whipping the oil at RPM.
Just because it's a 10 qt. pan doesn't mean that's the right amount.
If the pan was off and you set it on your bench at the angle it will run in your boat, maybe 12 to 15 degrees or more, and added 10 qts of water I'm sure you would find it is up over the windage tray and that's what causes the problems.
Also, use a good non-foaming oil like Valvoline Racing 40 wt. I don't like the Multi-grade in a boat. Actually, the "W" in 20w50 stands for "Winter" not weight as most believe.
If the motor is in the boat and together try like Dragboats advised, run it a couple qts. low and see if that fixes your problem. Shallow boat pans are the problem, 8" deep and deeper work better if there is room.
An oil cooler is more important than 10 qts. of oil, more oil just takes longer to get hot but does nothing to cool it.
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[ck7684]

I'm having the same problem. Milodon pan on 454. It drops right at 4000 rpm. So far I have dropped it down to about 8 quarts of oil. It still drops but seems to recover right away. I didnt have time to play with it much though, and now the lakes are frozen. I have heard that 7 qts should be run in the 10 qt pan...it's frustrating for sure...

[alien2]

Milodon makes a little plate that goes between the pump and the rear main cap to keep the oil from running up the back of the pan on acceleration.
If this only happens on hard starts or sudden acceleration this might help if you know the pickup heigth is right and at the very back of the oil pan.
Windage problems usually don't go away unless you turn less rpms.
Sounds like you have a different problem if the oil pressure comes right back.
Once you have this problem it's so much work to check for problems with the motor in the boat . . . No oil pressure, No motor, but you'll get gold dust in the oil filter.
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[alien2]

I have a 1978 Cobrajet w/403 Olds that looks just like your's except it's yellow. Bought it "new".
I've had several Jets, but always kept that one. Kids use it now.
I just don't buy the oil return being a problem in a motor that turns less than 6000 rpm . . .
I run Chevys now and sometimes WFO for long periods of time and wet sump with no problems.
Good Luck !