The Stovebolt Site Forums The Shop Area The HiPo Shop Excess oil pressure in 66

I have a 66 c20 which I put a refurbished 350 crate motor in. Not a performance motor, just a bone stock 4 bolt main 350 with dual exhaust and a quadrajet. My stock oil pressure gauge reads from 0-60psi. I have about 5000 miles on the motor. Since day one, the oil pressure when on the freeway or any mid range rpm is over 60psi. At idle it is about 30psi or higher. I broke the motor in with 10-30, did my first oil change with 10-30, and my recent and last oil change I switched to 5-30. Seemed to make it a bit lower at idle but just the same at higher speeds/rpm. My question is...is that normal? To me that seems way high. I'm not sure what the truck originally came with as far as the motor, so I thought maybe I have an oil pressure gauge suited for an inline 6? Any help would be appreciated.
Thanks much.

I had a 260 ford that ran like that for 120,000 miles. I'm not sure if the two engines equate, but for what it's worth.

thanks. Yeah, I guess it's better than the other extreme which would be low oil pressure. My concern is that I don't want to damage the engine, blow oil by the valves or something along those lines. Not really sure how it could adversely affect the motor.

Have you ruled out the gauge? When I put a 350 in my AD, I replaced the gauge and it pegs out, cheap repop!

thanks for the reply. I guess it could be the gauge, not really sure. Are there different gauges for different motors or are they all the same? It is definitely the original gauge, but not the original motor.

You don't say what kind of sender/gauge you have but if it's the newer total electric then I would look at making sure they are a matched pair. Different oil pressure senders vary output with the same amount of oil pressure. Case in point, my 350 motor runs, of all things, a Jeep sender due to my odd OEM (Packard) gauge. One size does not fit all. You can test your gauge with a variable resister and then hunt down the right sender. Good luck.

I think newer engines run higher pressures. The V-6 in my '97 runs in the 50-60psi range at idle...It took me a while to get used to seeing that.

cm

Put a direct-reading gauge on it and confirm that your dash gauge is accurate. It's not uncommon for a small block Chevy to run those pressures, and it won't hurt a thing. It probably had a Melling high-volume pump installed when the engine was built, or some other high performance item. It's possible to put a lower-pressure relief spring in the pump, but the oil pan has to come off to do it. Other than consuming a tiny fraction more HP to drive the pump, there won't be any ill effects to more oil pressure. It definitely will not cause leaks or high oil consumption.
Jerry

Hotrod, please enlighten us 'grasshoppers', what is a "direct reading gauge"?

It's one that installs into the oil passage instead of a sending unit, and reads oil pressure through a flexible tube instead of sending an electrical signal. On a smallblock Chevy, the pressure port is right beside the distributor. I've discovered a bunch of inaccurate electric sending units, but they generally read too low, not higher than normal, or they are slow to indicate pressure changes.

One of my competitors on the dirt track put so many washers behind his oil pump relief spring that the load of turning the oil pump would stall the engine. When he got it started and floored the gas, the pressure split the side of the oil filter. He had the relief valve jammed down tight so there was no way to relieve excess pressure.
Jerry

I wish I had your problem. I'm almost zero when hot at Idle.

I wouldn't worry about your Oil pressure. I put a new Stewart Warner sender & gauge in my rebuilt 327. I get around 80 psi at start up running 10/30 Oil. After warm-up she idles between 20 & 30 psi. Running on the highway its usually around 60

YOu have more than enough pressure but if its ever low I've always hear that as long as a chevy has at least 10lb per every 1000rpm's your good to go! ...just thought I'd throw this in

66 uses a direct reading gauge. I doubt they are accurately calibrated, esp after 45 yrs. Mine pegs when cold also, & my engine has many miles. I'd worry about something else.

what oil pump is in it?
hi flo/hi pressure????????