Kelley

I just changed from Mobile 1, 10W 30 to Shell Rotella T 15W 40 in my ’66 327/300 and my oil pressure skyrocketed. Before the change it always pegged the gauge at 60 when cold but would back off after it warmed up. Now it pegs the gauge whenever there is any load on the engine, cold or hot. Once it is warmed up it will idle at 15 psi but go immediately to 60 when I take off
Should I be worried about running this much pressure?

midyearvette

your numbers sound a little weird to me. 15 at idle is a little low but if it responds as you say, should be no problem. the issue is you really do not know the pressure with a pegged gauge. i would try to verify it with another one to see just how far above 60 you really are. the 40 wt. could be doing this.
if you are still running the canister filter, too much pressure can implode some of the brands out there, spin on ones should be ok
all in all, i don't think you have any worries, just a weird pump or pressure spring. stock oil pumps are all that's needed for 99% of the builds...jmo....

Westlotorn

Sounds like the oil pump by pass is stuck in a partially open mode. At idle hot it lets too much by, at speed it does not let enough go by. Idle should be at least 30 PSI hot.
This is just a guess, not exact science. Keep us posted.

Jebbysan

Sounds to me like like you run a HV or Z28 pump like everyone does and when the oil is cold the resistance is enough to peg the gauge.
Then when warm the bearing clearance is such that is bleeds off the way it should.....
15 at idle is fine......10 psi per 1000 is a rule of thumb. it is not so much how much overall pressure there is but how the needle sweeps when you rev it.....a nice quick even sweep is perfect....a slow pathetic climb is trouble.
I run 15w40 flavor of the week....Delvac,Rotella whatever in my 327....when cold it will peg the gauge but quickly evens out to around 35 at idle then 18-20 when warm. This is acceptable to me as the rods on this motor were set at .015...mains .002-.0025
I never run a HV or Z28 pump unless it is a race motor.....just not needed.
On a 560 horsepower 383....a HV pump costs 7hp at 6600 rpm....dyno proven with my own eyes back to back....7 horsepower more than your lawn mower....

I personally think you are fine....but if worried switch back to thinner oil....all that happens when the pump over pressures is it bleeds off through the bypass.

BTW: I see the gauge almost peg at 60psi at 6000 rpm.....perfect

Peace,
Jebby

Pop Chevy

Jebby, I hope you just missed a 0 on your rod clearance ! yikes !

Jebbysan

I did! Typo! .0015 was where they all fell....


Jebby

Kelley

I drove the car tonight and after warm up it actually idles at about 20 psi rather than 15. As I accelerate the pressure increase is nice and smooth, about what you would expect. But still goes all the way to 60 every time

I have owned the car for 6-7 years and drive it regularly. I believe someone before me has done some engine work on it. It currently has side pipes (that I installed) and I rarely ever go out that someone doesn't comment on how the car sounds

I'm picking up the impression here that the 60 psi may not be a problem

Jebbysan

It is not....have fun

Jebby

Westlotorn

With a Stock Pump, .002 Rods and Mains, good cam bearing fit we used to see 40-45 at idle on many small blocks, Sealed Power Engineers used to teach that a well built engine will have enough pressure to open the oil pump by pass by 500 RPM.
With Performance bearings the bleed off would drop the pressure, they have much more clearance at the bearing parting lines causing excess bleed but also allowing for good flow at very high rpm. A high volume pump would fix that though.
I agree that 60 PSI is good, but I don't like to see pressure drop off at idle. Even though GM says all you need at idle is 7 PSI. My old Suburban with a stock 350 is still working in my neighbor's carpet business, I put new main and rod bearings in it at 150K because it developed the GM front main knock, my neighbor bought it from me at 170K and now has 300K on it working in his business, at 300K it still has a solid 40-45psi at idle with the original stock pump. I did use .001 under Main bearings to close the clearance up on the tired old crank. This engine is not a Corvette and never see's over 4,500 RPM and I know that makes a difference on rods and mains set up.

Westlotorn

Federal-Mogul has used sintered Rod and Main bearings for over 25 years, they do out perform the cast bearings in all the OEM tests. Now with modern pushes towards Zero Copper, Zero Lead and zero Tin the newest bearings are all aluminum enhanced with silicon and are far better than mixes than were made in the 70's.