Thread: 406 low oil pressure

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I was wondering if anyone might want to weigh in on an oil pressure issue.
Here's the details:
.030,forged flat tops, dart 215 aluminum pro 1, hyd roller 236/242 .560/.578 108 lsa, king bearings .002 on mains and rod clearances, scat rotating assembly, milodon/high pressure/high volume oil pump, moroso 6 qt pan with baffle and matching pick up.

I measured about 3/8 inch from pickup to bottom of the sump.
When cold, oil pressure idles about 40psi
When warm, it idles about 5-8psi and revs to about 25. No knocks or low end noises and the roller rockers and valve train seem to be getting plenty of oil.
also, I have checked with another mech gauge and it reads the same..
All oil galley plug put in by my reputable machine shop which i have had sucess with in the past.
I was thinking about changing the pump but wanted some inputs or ideas first. Any help is appreciated.

you bearings size are bigger then you think ? what oil and how hot? theres only two plugs that could be left out and you would have no upper end oil so thats not it . so i bet it is in your lower end

I hate to admit it Pat but when I measured the rod clearance, I got .0015 ( plastigauge) with the King bearing. I ordered clevite 1 over race bearings and then read .002 (plastigauge). I'm thinking I should had left the kings in because they were probably really around .002. My lazy a&& won't get a sunnen.
Do you think that I should change the filter adapter first? thanks Pat

I had valvoline 10w 30 race blend but changed to 15w 40 rotella to see what would happen. No difference. 5-7 psi at idle at 190 degrees and revs to 25-30 psi at 3000rpms.

Originally Posted by flanker1970

I hate to admit it Pat but when I measured the rod clearance, I got .0015 ( plastigauge) with the King bearing. I ordered clevite 1 over race bearings and then read .002 (plastigauge). I'm thinking I should had left the kings in because they were probably really around .002. My lazy a&& won't get a sunnen.
Do you think that I should change the filter adapter first? thanks Pat

no you could try another filter i realy think you have more then you think for size all the ACL s and KINGS H bearings are bigger right off the bat i used many and there allways to big. try strait 50 w it may come up and if it will then you know your big .you do not have to buy a sunnen theres others that are not so much $$$ buy your self some mics and a bore gauge

Been there had it happen to me on my 305 build. You have excesive main bearing clearance. rmove the timing cover and tining chain. Grab the crank snout and lift it up and down an pay close attention to the main bearing and you will see it lift up slightly. My crank was supose to be .010 on the main it ended up being .016 and even with a big block pump i had only 40 psi oil pressure and 5 psi idle.Need to pull engine and mic the crank or even stick in some red plasti gauge and see what it come to. I bet the green doesnt even make contact. Sorry man i now check all my main clearances. I use to just check my rods.

as always, thanks for the advice.