Do you have a gen4 or gen 6 block? They take different adapters.

If oil is 20 50 the only way switching to a different 20 50 will change anything is if oil is diluted by fuel/contaminated or its foaming and new stuff has better properties

It's a mark IV style Dart block...:)

Don't have much dilution... A/F ratio runs high 12's to 13.0 cruising @ 3500 to 12.5 WOT.. :)

I had an engine that was overfull and aerated the oil.
difference in that was the engine had to sit for a while 'till the air got out of the oil before the pressure would come back up...
This one will come back up after a few seconds at a lower RPM

You may need a oil pan with a kick out and better baffle's in it. 4.250 stroke can whip up the oil on a straight side pan.

So, I changed the oil to Valvoline VR1 20-50 and the filter to a Wix racing 5122R. Took it out today..
Don't have exact readings as my dash gauge is off a bit and my buddy dropped my "work" digital gauge in the lake.. (started working again now that it dried out.. phew....)

However, the pressure WAS dropping on the dash gauge once I got over 5000 RPM.. Oil temp was steady at 150 degrees measured at the oil pump outlet...

Cut the filter open AGAIN.. no big flakes this time but it was a little sparkly (maybe 3 hrs run time)

SO, now I need to decide if I'm throwing the stock engine back in and tearing this one down AGAIN or throwing some boost at it and run it 'till it pops... :cool:

Guess on a positive note.. If I HAD the blower installed I wouldn't be running over 5000 RPM all too often. :grinser010:

If you have run it some and changed the oil, after the 1st time seeing metal is not good...

So here's the deal.. Sorry if it's a little long winded.....

When I got this engine together, I fired it up in the garage before heading to dyno.. I cut the filter open and found a substantial amount of metal in it..
I figured, no biggie.. left over stuff from assembly. Put another filter on it and ran it some more.. STILL a bunch of metal.. Started investigating and found my timing chain was TOO TIGHT and it wiped out the lower portion of the cam bearing and my front upper main..

When I was assembling the engine I noticed that the timing chain seemed tight.. I had to start the sprocket on the cam dowel and rotate the engine to walk it up on the nose of the cam to get it on.. I contacted the manufacturer (Rollmaster) and was assured that was normal for their timing chain sets. Well, OBVIOUSLY they were WRONG.. It would appear my timing set was mis-boxed and was for a line honed block.. Rollmaster makes the gears slightly larger for line honed engines to take up chain slack.. UNFORTUNATELY they do NOT mark the bigger gears in ANY way.. :angry-smiley-055:
(have a cheap Comp chain on it currently)


So, anyhow, I had vacation and dyno already all scheduled so I replaced the cam bearings, rod bearings, and mains. Cleaned everything best I could but didn't completely disassemble the engine.. I then went to dyno... Made GOOD power.. Engine ran GREAT !

I installed it in the boat (less blower) Ran it for a couple outings but STILL kept finding metal in the filter.. I pulled the engine, COMPLETELY disassembled it.. Inspected and found where some debris had gone through the bearings, but did NOT find a source of the metal.. Cleaned EVRYTHING thoroughly !
Flushed the cooler and lines with mineral spirits 'tll not a single speck of debris came from it..

I installed the engine back in the boat.. Went out and managed to break the gimbal ring and spin the boat at 85mph.. Pulled the engine from the Corsa, put a stocker back in then Bought a Velocity 290sc and just got done installing the engine.....

I've run the engine now maybe 10 hours in the Velocty.. Changed the oil 3 times... First filter had a couple brass & a few steel flakes with some fine shavings. Second filter had a couple steel flakes, fine shavings but no brass. 3rd filter had less run time.. NO flakes but is STILL sparkly looking...
AND am dropping oil pressure above 4500 - 5000 rpm..... but it comes right back up when I back out of it..


I'm involved in this hobby 'cause it's FUN.. :Whatever:

I had this problem last year with oil pressure drop at high rpm on a pair of 489s. Mine was anything over 4800. Ended up being a windage issue.

So, how did you fix it ?

Changed the miloden pickup to a mercruiser. Also had truck pan last year. This year running 8 qt mercruiser with windage. My problem was most likely the pickup.