I have a fresh built 350 bored 30 over. Cold crank idle oil pressure is 50 to 55 psi. After driving about 30 miles idle oul pressure drops to 15 to 20. Any suggestions
You may not have any issue with that. I had a 71 LT-1 Vette for years that ran 40 to 50 pounds at speed but idled at 10 to 15. Solid lifter motor though, so it had restrictors in the journals. There's another thread on here that has no pressue at idle. Now that is an issue. My response will move you back to the top and like AAA, there will be folks by to help at any minute.
you need 10 psi per 1,000 rpm at operating temps. read Smoky's book " How to Hot Rod Smallblock Chevys"
I don't know if it has anything to do with it, but when I cut the truck off. It sounds like air bleeding off for a couple seconds?
Make sure that you have not over filled the crankcase. Too high oil level will allow the crank to whip up the oil.
Sounds like your within a acceptable parameters to me. I wouldn't be too concerned. It's not gonna carry cold start-up psi once it's warmed up to operating temp, if that's what you're concerned about. Without digging out the old Motors Manual blue bible, I seem to remember GM calling for 10-15@idle, & 35-45@operating temps. Or somewhere's in that neighborhood. I'd drive it.
I agree with RACEMASTER . I bought a used 56 chevy that never had over 15 psi and drove it that way for two years.
Another chiming in that you're fine, probably even running oil a little too thick. The 10 psi per 1000 rpm is straight out of Bob's the Oil Guy as well. They seem pretty smart.
Just discovered something else that don't seem right. With the engine running, it has so much vacum you can't hardly get the oil fill cap off. The pcv valve seems to be free. I even removed it. It has a lot of vacum on the hose. It runs from one valve cover to the other with a t in the middle hooked to the carburetor. Should there b this much vaccum?
I don't think so. Like I said, there's a vaccum line that goes from one valve cover to the other, a pcv valve on the drivers side. Teed into the carb
You need to separate those vac lines down to one with one PVC valve on it. (To make sure. You have two PCV valve's ? ) Then use other valve cover to let fresh air in with a breather or vented cap.
Ok, slow down. The pcv valve is SUPPOSED to go from the back of the carb, (manifold vacuum) with ONE hose to ONE valve cover. The OTHER valve cover gets a BREATHER. Period. No T's ever. The PCV needs to pull air through, not create a vacuum inside the engine.
Your PCM system is a problem for sure. You should have clean filtered air enter one valve cover and travel through the engine by vacuum generated by the PCV valve scavenging blowby fumes and then carried to the intake to be burned . Run a hose from the air cleaner or use a filtered oil filler cap so that clean air only enters and a single nose from the opposite valve cover with the PCV in it . Preferably, the valve should be placed in a grommet at the valve cover. Make absolutely sure that there is a baffle at the point where the valve is plumbed or you will have oil consumption problems. That should cure your air noise upon shut down.