Hi ,I have got a slant 225 ,It is a fresh engine ,rebore ,new pistons ,cam ,head etc.

On start up cold idle 25 psi
Warm,hot idle 25psi in drive
cruising at 55mph 45 to 50 psi
stationary at 2500 rpm gauge showing 45psi
only done about 500 miles since rebuild and not blowing smoke or using oil
Oil pump was checked but not rebuilt.
I have been told oil pressure is o.k but I feel it is a little low.
Any suggestions /comments would be welcomed...
cheers Low62s

Those figures sound fine to me. The general rule is 10psi per thousand rpm. So for example, 2500rpm you should have at least 25psi.

~THOR~

_________________
1984 D100 Shorty Custom
Certified Auto Appraiser - RevItUp Classic Appraisals
President - Cherry City Bombers CC
Part of Tyrde-Browne Racing

Sounds a touch low for a fresh rebuild though. I would consider cleaning out the oil pump pressure relief spring. Do a search on the site to find some excellent directions by Doctor Dodge, the slant six guru.

The pressure readings are OK but I would like to see a little more hot idle pressure... just for "peace of mind".

The good news... reusing a worn factory oil pump with a "known quality" and tested drive gear reduces the chance of OP drive gear failure.

The bad news, a used oil pump has impeller wear that reduces it's ability to make low RPM pressure.

To get higher low RPM oil pressure you will have to rebuild or replace the pump... or use heavier weight motor oil.
DD

Thanks for the information thus far much appreciated,Do you think oil pressure would improve with a heavy duty pressure relief spring.
Thanks Low62s

The releif valve only controls high RPM, max pressure, it will not help with low RPM pressure drop.
DD

DD
Just a thought. What do you think about removing the drive gear from an old pump, and installing it on a new pump?

_________________
Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Charrlie that works just fine.
Frank

_________________
Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered

Yes, many "in-the-know" SL6 engine builders do just that.

During our research on the OP drive gear failure problem, we found that Chrysler specs called out a special "M7" (high nickel content) iron to produce the drive gears.

Aftermarket oil pump makers (Melling & DynaGear) said they use "gray iron"... sourced from the lowest bidder for finished gears.

From that point forward, I stopped using the gears that comes on a new (aftermarket) oil pump. Instead, I swap-on a known, used factory gear or one that I have had case hardened. (carborized)
DD