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Discussion Starter #1
Guy's , we may have mentioned this but I can't find it.

I have my motor apart, Specs are in the middle, not high or low side but stock specs on my Scat crank. I am using the Mellings Select 10550 hi volume pump. There was a note in the package that this pump has the Pink pressure spring and regulates pressure to 70 psi. 25° weather start up is close to 80 psi and hot (185°) idles at 60 with 15-40 oil(Rotella). I switched to 5-30 oil and psi drops into the 60 psi range during cold. I had planned to switch back to 15-40 during summer but am wondering if I need to swap pump pressure springs while I have oil pan off ( rear gasket leak on one piece gasket)

The pump includes a black spring to drop psi into the 60 psi range. I tempted to do this before but left well enough alone.

I need some input. Think I should leave the 70 psi spring in or replace it with the black 60# spring.

Dave?? Tim? Anyone else ?
 

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You may gain a few hp by going to the 60. And it won't harm a thing, just make the relief open sooner or more.

If you had 60 at hot idle, you probly had 70 hot cruising?

You thinkin your high oil pressure may be part of the leak?

Did you put a little silicone on the back of the rear main cap at the block joint? Easy to forget. Ask me how I know:)
 

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Don I'm not that far along on mine with the 10552 pump. From your experience I think I'll go with the black 60 psi spring though.
 

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Discussion Starter #5
OK, guess I was thinking correctly by going to the black 60# spring. I was thinking it would be ok to leave the 70# spring and just alternate oil viscosities, but I am used to running the 15-40 oil.

One thing that has caught my eye is the mating surface on the rear main cap to new oil pump. When I pop it on to the dowels with out being tightened down, there is a little "rocking" and that is leading me to think the mating surface on the main cap to oil pump surface , is not perfect.
Now this surface is parallel to the sealing surface of the rear oil pan gasket seal. My thinking is that IF there is a leak at the cap to oil pump surface, it could be shooting a hi pressure ( 70#) stream directly on this deal, thus causing forced pressure on the sealing parting line of the pan and gasket. Possible? So, I remove my main cap, stud, and dowel pins, I will lap this cap to oil pump surface on a piece of glass with fine sandpaper to reveal and uneveness and hopefully make the surface true.

Tim, No I did not add rtv on those pan end seals ,only the corners as I always do, but it getting a new gasket, another new blue main seal and RTV. Good luck for me as winter storm hit this morning after blowing sand for 3 days and I will not be missing any cruising.

I am really not concerned now about oil temp as since I got this motor together and added the rear intake bypass water lines to T-stat adapter, my water temp is lower by 10-15°, so I am good here.

Thanks All for the input, black spring it is.
 

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Tim, No I did not add rtv on those pan end seals ,only the corners as I always do, but it getting a new gasket, another new blue main seal and RTV. Good luck for me as winter storm hit this morning after blowing sand for 3 days and I will not be missing any cruising.
Don, that wasn't what I was talkin bout. I'm saying UNDER the main cap. From about the thrust flange back, and a very very thin layer. It's metal to metal and oil can seep out there.

Good catch on the pump surface.

Does that pump have a deflector on the relief valve? Which way does it blow?

Yeah, I'm taking refuge from the snow after being out in it all day.
 

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Discussion Starter #7
Don, that wasn't what I was talkin bout. I'm saying UNDER the main cap. From about the thrust flange back, and a very very thin layer. It's metal to metal and oil can seep out there.

Good catch on the pump surface.

Does that pump have a deflector on the relief valve? Which way does it blow?

Yeah, I'm taking refuge from the snow after being out in it all day.
Yes, Under and over on the gasket. I got that.

Main cap to oil pump surface had a high spot. Lapped the mount surface , All good and even now.
Discovered I got the wrong one piece gasket, 70 model block with the late model pan. I picked up the narrow seal job.

Relief port must be internal back to suction side as I don't see a port back to crankcase.

Black spring installed.
 
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