oil pressure inline 250

[samstheman]

I have a new rebuilt chevy 250 inline 6. decked Clifford cam and valves and Clifford machines redid head 4 barrel headers runs and starts fine. Motor might have 5000 miles on it. Im running straight 30 weight oil at cold start idling pressure is around 18 and idle a little higher than normal revs to 42.
When normal operation temp oil pressure down to 8 to 10 no noise idle is around 700 and would rev to around 38 pressure. Does this sound right should I change oil to 20x50 im in SoCals 70 to 85 deg most days to increase pressure or leave it alone.

['68OrangeSunshine]

I run my 292 L6 in Arizona, where we have an even wider temperature range than Calif. I always run Valvoline Racing 30. My oil pressure is about the same as yours, 15 - 40 PSI, depending. I have Clifford headers, Offy intake, Edelbrock 1404 500 CFM 4V carb, HEI, Crane cam 260H. Thirty over bored. 1.84'' Intake valves, 1.5'' Exhaust.
It idles at 750 RPM, Shows 180*F when at operating temp, Indicates 17.5'' Hg. Manifold Vacuum. Purrs smooth after warm up.
Without seeing it, smelling it, and hearing your L6 in person, your indications, as provided, sound ''nominal.''
Keep the straight oil. Old tech works best in old tech.

[samstheman]

Thanks for ur reply. But doesnt my pressure sound to low at oper temp below 10 at 750 rpm idle.
No noise and seems to run fine and guage is accurate. Does urs run at 18 at idle when all warmed up ??

['68OrangeSunshine]

Mostly, I don't pay much attention to the OP gauge. I'll start it up later and make some observations.

['68OrangeSunshine]

Hi Sam,
I had to run a letter to the post office, so I made some notes of gauge indications:
Start Up: 650...RPM/OP...38PSI/VAC...15''Hg/H2O...130*----Odo...718.4
Running at 50 MPH/2100...RPM/ OP...45PSI/VAC ...10 to 15/H2O..180*
Idling at PO -- 900...RPM/OP...45PSI/VAC...18''Hg/H2O...185*----Odo...722.1
Home--700...RPM/OP...35PSI/VAC...17.5"Hg/H2O...190*---Odo...725.6

My oil pressure seems to get up, and stay up. I do have a high volume oil pump. I know everybody advised against it, but I got one anyway, and it has not given me any problems in 16 years.
Oil Pressure Gauge is a Stewart Warner 2-1/2'' mechanical.

[samstheman]

Thanks for the complete rundown very complete ty. Mine I think is low now I need to find out why. Or just put a happy face sticker over gauge and forget about it. Thanks again for the complete info perfect.

['68OrangeSunshine]

Originally Posted by samstheman

Thanks for the complete rundown very complete ty. Mine I think is low now I need to find out why. Or just put a happy face sticker over gauge and forget about it. Thanks again for the complete info perfect.

That might be normal for a stock regular flow oil pump. I din't know. Unless the OP gauge is pinned or pegged at either end, it's probably OK.


Nice valve and lifter covers. What carb do you run?

[D13]

My old sixes went many a mile on 10psi at idle. The old oil pressure light had a 5psi threshold. If you have a stock volume pump, 15 at idle would be good.

The drive for the oil pump is not the best. The experts recommend not running a high pressure pump due to the distributer gear wear.

['68OrangeSunshine]

Originally Posted by D13

The drive for the oil pump is not the best. The experts recommend not running a high pressure pump due to the distributer gear wear.

I think I have a bronze gear there now. I have had to shim the HEI distributor. It was a Chinese ''Assault Racing'' unit and had a dud module out of the box. No real warranty, so I gutted it and replaced all components with the best I could get. That was 12/2016. So it's been OK for now.