396 experts need help

[gmc684x4]

Why such a thick oil ?
Most guys i know run 10/40 or even 5/30

20/50 is a diesel truck oil

Do you have headers?
Are they loose

Have you used comp cam lifters i have heard there fairly noisy

[69 customcamper]

Originally Posted by gmc684x4

Why such a thick oil ?
Most guys i know run 10/40 or even 5/30

20/50 is a diesel truck oil

Do you have headers?
Are they loose

Have you used comp cam lifters i have heard there fairly noisy

I tried 5/30 and oil pressure dropped to 25 when it got warm.

I have cast manifolds and yes I hear a slight exhaust leak which I am going to address this weekend. But that should not make it idle rough as the noise increases or am I wrong ? Bolts are very tight.

Standard melling brand Hydraulic lifters. Started with a chinese brand which I swapped already as at first a few would not pump up.

[weim55]

Is your 50 psi idle oil pressure reading with the engine and operating temperature or cold? What is the oil pressure hot at cruise rpm?

Steve weim55 Colorado

[69 customcamper]

Originally Posted by weim55

Is your 50 psi idle oil pressure reading with the engine and operating temperature or cold? What is the oil pressure hot at cruise rpm?

Steve weim55 Colorado

It is 50 psi weather cold or hot . So cal has not been to cold in the mornings lately. It will go up to 55-65 depending on speed.

[geezer#99]

Originally Posted by 69 customcamper

I tried 5/30 and oil pressure dropped to 25 when it got warm.



Standard melling brand Hydraulic lifters. Started with a chinese brand which I swapped already as at first a few would not pump up.

Nothing wrong with 25 psi hot idle. You only need 7-10 per 1000 rpm.

When you changed lifters did you try to break the cam/lifters in again.
Sounds a lot like a cam getting wiped.
Big blocks are notorious for wiped cams.

[69 customcamper]

Originally Posted by geezer#99

Nothing wrong with 25 psi hot idle. You only need 7-10 per 1000 rpm.

When you changed lifters did you try to break the cam/lifters in again.
Sounds a lot like a cam getting wiped.
Big blocks are notorious for wiped cams.

When I removed the lifters the cam looked fine. Also it is not noisy until you drive it and it warms up . When it got to 25psi It was even noisier.