401 Oil problem on start up

[dwg86]

I have got about 400 miles on my rebuilt 401. It's been about 6 months since I started it last. Well the weather got warmer today, so I charged the battery and started it up. It took a long time to build oil pressure. About as long as it does after an oil change. Once the oil pressure came up it was good(about 80 psi). It always has high oil pressure cold. Once its warm at idle its about 45. At cruise running down the road its about 60-65.
Because of all the problems with flat tappet cams wearing, I am running diesel oil 15w40. I know this may be a reason for the high oil pressure. I am going to change to Valvoline VR1 10w30.
I am running a napa gold oil filter, I can't remember the part number but it's whatever napa calls for the 401. Is this the filter I should be using? Is there a different napa filter or brand I should be using? I remember something about an anti drain back valve in the oil filter that should be used on the AMC V8. It always takes a little time to build oil pressure, but this time it took too long.
A little more info on the oil system installed on my 401. It has an 8 quart milodon oil pan with dual external lines. Mid wear plate installed in the oil pump, internal oil line, and an external line feeding extra oil to the dizzy gear.(I know there are different opinions on the internal and external oil lines, but I built this engine a few years ago). Any help would be greatly appriciated.

[jeepsr4ever]

If it were me I would ditch the dual lines. The dual lines split the suction and then bottle neck it at the pickup. This creates less suction on start up. It is a problem alot of people have had. It could also be that your oil pressure bypass was sticking but I wouldnt be hesitant to blame those dual line.

[AMX69PHATTY]

Maybe just for fun, also try an AC Delco PF24 Oil Filter to see if it makes any difference.

[dwg86]

Maybe just for fun, also try an AC Delco PF24 Oil Filter to see if it makes any difference.

Does that one have the anti drain back valve? Have you had the same experience and that oil filter cured the problem? Just curios.

[AMX69PHATTY]

Yeah, both the Napa and AC have the drainback valve. It's visible through the circle of holes around the perimeter. It's a rubber or silicone disc inside the holes, have seen them as pale red and black in color. But it seems the AC turns off the oil pressure dummy light faster than the Napa filter, for me at least. I had started using the Napa filter from what I read here, but it seemed to take a couple few seconds to turn off the dummy light, where the AC does not. At least for me anyways. I have been running Roptella-T 15w40. And there are 2 different Napa gold filters, the long one and the short one, and the long ones I got did not appear to have the valve, but the short ones did, but they still took longer to turn off the dummy light. I don't know if it would be the same way for anyone else or not.

information believed accurate, but not guranteed

AMC V8 Oil Filter info

NAPA ..... = #1049 = Long = PH11 ( no does not have drain back )
GOLD ..... = #1258 = Short = PH25 ( yes has anti drain back )

FRAM ..... = PH11 = Long
............. = PH25 = Short

AMC ...... = 944345 = PH11
............. = 996900 = PH25

AC ........ = PF-31= PH11
............ = PF-24 & PF-30 ? = PH25

STP ...... = S25 ( AutoZone )

WIX ...... = 7, 17, 51049 = PH11
............ = 4, 51618 ?, 51258 = PH25

CHAMPION . = OF22 = PH11
................ = OF06 = PH25

CHRYSLER .. = 2196909 = PH11
................. = J3215877 = PH25
-----------------------------------------------------------

[dwg86]

The boys wanted to take the "big jeep" to the ball game. After the oil got warm the oil pressure came right up when starting. I think some of my problem might be the oil. Oil pressure was way to high. I have to wait for the temp to get to 180 before I can drive. I started driving it before it got warm, oil pressure hit 100 psi at one pointe(autometer mechanical gauge). After the engine got warm it idled at 60 psi, running down the road at 80psi. It has a good size cam in it so I have to get rpms up to shift(oil pressure close to 100) . When I was running 10w40 I didn't have this problem. I bought a case of 10w30 Vr1 oil I'm going to try. This oil is suppossed to have 1300 ppm zinc and 1400 ppm phospherous(good for flat tappet cams).

Oh yeah on more thing I remember, I put in a high pressure spring in the pump from Sharps Supply, when I built the engine. I think I may still have the old spring from the new pump kit. But before I change it I am going to try the thinner oil.

[ironman_gq]

your bypass plunger could also be sticking. when you go to change that spring make sure the piston moves freely in its bore.