oil pressure
If you're running a high volume pump, you should be getting plenty of flow to your bearings, especially since you've restricted oil flow to the top end.
FWIW, the Hemi oil spring (PN 2406677) is rated at 75 psi. My DC Racing Manual recommends 50 psi up to 5000 RPM plus 10 psi for each additional 1000 RPM increment of crankshaft speed so your oil system now good to 9500 RPM.
With a 40 grade oil (ie, 10W-40) and a high volume oil pump, I would expect that your hot idle pressure would be well above 20 psi. I get 40-50 psi at hot idle with the original 200k+ mile oil pump in my slant six with 10W-30. Running high pressure with a high volume pump unnecessarily stresses your oil pump's drive gear.
Shimming your oil pump's relief valve spring will not help your hot idle pressure. The oil pump is obviously what generates the flow and the developed pressure is the result of downstream flow restrictions. The relief valve prevents the pump from building excessive pressure resulting from high flow and/or high viscosity fluid friction. See
Engine Wear.
Are you sure that you don't have loose bearing clearances?
All interesting comments. I had synthetic 20w50 in it this summer, I think I might have switched to it too soon, may have some rings that aren`t seated yet. Only about 500 miles and 2 trips down the 1/4 in it , plus some hotrodding. ????
It actually has tighter clearance than I like, about .0022 .0024 when built. I would have preferred .0027 to .003 .
And YES, shimming the oil pump spring DID help my hot , low oil pressure !
I had an adjustable Milodon relief valve in it for a while, and really got it high playing w/ it , and took it out for the currant set up. If I had it on the engine stand to play w/ while running the pump, where I could really examin things , I would still be running it. But kinda scared to mess w/ it , my set up seems to be ok, I`ve checked diff. main and rod bearings a few times and all seems well for now. The low pressure at hot idle still bugs me tho. One thing is, the pressure is read at the back of the block, after it feeds everything in the engine on a big block .
(440/505" wedge) I haven`t tried a straight weight oil tho---------
I owned two hemi`s back in the day, raced one for 14 yrs. , they are set up oiling wise better than the 440 engines, they have dedicated oil return holes, front and back, in the block straight from the corners of the heads, and a 1/2" pick up to start with. We ran hi volume pumps, and really large alum. tie rod tube pan with 9 qts of oil back then, it had .003 clearance straight across the board , from the factory.
The hemis were both spot on in machining from the factory too.
This 1966 block required only .002/.003 decking to blueprint, so it was pretty close too-------------
My biggest problem right now is traction, but at my age , I`m not sure I can get up inside the trunk rear cage struts to tub it , too stiff and beat up now. May just try 10x29" slicks first. ( not that I`m going to race it that much at 72 anyway ! )----------And the beat goes on ----------
