Can anyone tell me why I have high oil pressure? I have a 383 Stroker motor with a stock oil pump. I run 10/30 Castrol oil and had 50 lbs at idle and 70 lbs above 1500 rpm hot. I just changed to 5/20 Castrol oil and I now have 35 lbs at idle and 60 lbs hot at 2000 rpm. The only additive I put in is a pint of Comp Cams camshaft break in oil to replace the anti-wear components the EPA made the oil companies remove. Does this give me high pressure? The build sheet for the motor has the bearing clearance so tight I was concerned that I could spin a bearing. The motor is 4 years old now. My main concern is the camshaft and distributor gear wear.
Thanks, 68 Vetteman

 

First off, I would not count on the gage indicating correct pressure. Not one of my gages in my car are correct. I have a Melling standard volume pump with normal spring, not the high pressure spring, and I am pegging the meter when cold, and never goes below 50 PSI. And, what is the harm in high pressure anyway.....? And as I said, who knows if the pressure gage is accurate.....

My clock always wants to go faster than real time.....I guess its cause its a Corvette clock, so I have to back it up every couple days....big deal.

My brand new fuel qage reads empty when there is five gallons of gas left.....how do I know? When its almost of E, I still put 12 gallons into a 17 gallon tank...big deal.

My brand new coolant temp gage shows 150 degrees no matter how long I run the car with my 180 degree thermostat - I measured engine temp at thermostat housing with infared temp tool, and it read 180, so, when it says 150, I know its 180...big deal.

My voltmeter read 16 -18 volts, but my Fluke says its 13.5- 14 volts....big deal.

My speedometer says I am doing 60, when the car is probably doing 57, according to Tire Rack calculator with my different tires....and the radar guns on the highway....big deal.

I have no idea how to know if my tach is accurate, but its about right for a 3.55 differential...big deal.

Once you know the difference between all the gages and reality, its not really important to have accurate gages, and I ain't worried about it.

 

I have the stock gages and my temp gage never goes above 120 on the hottest day with a 160 degree thermostat.

 

Like mentioned before I would replace the gauges to get a real correct oil pressure New Motors can be tight and the oil pressure read higher until the break-in. Which might be as many as four 500 miles I would be very careful about running 5W20 oil up above in the sticky section there's a really good rating of what's in all the different oil brands you didn't say your type of Cam

 

Comp-Cams hydraulic roller cam.
I'll check out the stickey

 

I personally use Valvoline VR-1 racing oil. I remember when I first drove my 383 stroker with a solid roller cam. I was impressed with amount of TQ compared to my hot rodded 355 ci. I use a high vol oil pump, blocked off bypass, along with drilled out block oil restrictors to give priority oiling to the lower end.

What was your cams specs and which heads?

Enjoy your new motor.

 

I just got the build sheet out.
Main and connecting rod clearance is .0025 to.0027.
Cam specs intake-.495 lift, duration 270
exhaust-.502 lift, duration 276
I have the stock double hump "Fuelie Heads" with hardened valve seats
68 Vetteman

 

What is the. 050 cam duration. Your rods are not overly tight causing higher oil pressure

 

Intake 218 Exhaust 224
Lobe Lift .330 .335
Separation 110
Read the stickey for oil. Valvoline VR1 for future oil changes.
Does the Comp Cam break in fluid increase oil pressure? It's pretty thick. I won't need it with the Valvoline VR1 oil.
Thanks

 

In my opinion........ Assembly lube, breakin oil, and filter should be changed after about the first run in or about 30 minutes of first fire up. Then switch to some better motor oil. VR-1 comes in 10W-30 or thicker.

The motors i build get the Joe Gibbs breakin oil. If the CC stuff is like STP thick it could cause higher pressure. I'm just not familiar with it.

 

The Comp-Cam fluid is not as thick as STP but close. Almost the end of the year for driving but after seeing the oil sticky I'll change to the VR1 without any additives. That should lower the oil pressure. Thanks for the advice.
68 Vetteman

 

You indicated that you have a "stock oil pump". But, has your original pump been replaced with a rebuilt unit? If so, the main regulator spring may have been replaced and that could easily be the reason for "high" oil pressure.

If your oil pump is the original factory-installed unit, then the 'high' readings are likely the result of a gauge that reads high. You might want to plumb-in another 'test' gauge to check its accuracy.

Otherwise, the 'tight' main bearings could have less leakage because of their tight tolerance and that could also cause higher pressures than with stock-clearance bearings.

As far as what oil to use in your engine, I think a good brand of 10W30 oil or 5W20 synthetic oil would be best. If you feel the need for adding zinc to the oil (too much is not a good thing either) because you have solid lifters with stiffer-than-stock valve springs, so be it. Otherwise, you don't need to add it, IMO.

 

I use the VR-1synthetic racing oil my pressure pegs the gauge with the high pressure spring in the melling select pump with the 7 qt Milodon pan. I wouldn't be concerned with it being high, I would rather have a pegged out gauge at idle than 5 pounds at idle.I think your likely worried about nothing.I do intend to install new gauges to keep a better eye on things.

 

I have a GM Crate Motor (Fast Burn) GM uses a high volume oil pump. My pressure is 80 when cold and goes to 50 when warm. Don't sweat it high pressure is a good thing. I have 50K on motor, just changed oil pan gasket and everything was fine inside

 

Except that it takes HP to turn a high-volume and/or high-pressure pump when very little is needed. If you think the higher pressure at idle (and above) is better then gas money, so be it.

 

Thanks for the info. I installed a new "stock" pump out of the box when the engine was new. I'm thrilled the pressure is high rather than low. Next oil change I'll try just 10/30 with no additives. If the higher pressure doesn't wear the cam and distributor gear then I'm OK.
68 Vetteman

 

I would not be concerned ..Some people believe 60-70 psi will groove bearings.. Its an old wives tale.. I ve seen bearings after running 100- 120 psi and no such groove existed.. It takes a little extra power to turn the pump..thats about the only downside.. unless your high pressure is due to a clog or restriction somewhere.

 

Had installed a high volume pump in a 327, the clearances were around .003 the freaking gage was pegged during break-in and would not move until after cam break-in where the idle was brought down to around 1,500. Dropped the pan, installed the spring from the original oil pump, now the pressure was too freaking low, dropped the pan again, installed a shim behind the spring and was finally satisfied with the gage reading, so as was already mentioned, the pressure spring regulates gage pressure, the harm of too much pressure is that it stresses the distributor and cam gear. As already also mentioned try a different gage to verify the pressure.

IMHO, if after verifying that there's higher than normal pressure, would pull the distributor to check on gear wear, if it looks like a problem, then would drop the pan and check out the pump's spring.

 

Your oil clearance on the mains seems to be OK but it is the person measuring that might make an error. It could of course be tighter.

That said my blue printed 427ci has some miles on it now, I checked oil clearance many times during assembly and they were spot on for my engine.

It has run for a few years now and the idle is 50psi and anything above 2000RPM the gauge is pegged at 80psi. I am running the "Z28" version of the Melling pump.

 

If you really care about your performance motors you should take the extra steps. Like the "No oil bypass" and if you are running a stock block investigate options to make the mains have priority oiling. Also the use of 7 or more quart baffled pans. Then after motor breakin adjust the oil pressure with the oil weight.

min of 25-30 for hot idle. When you start getting over 70-75 psi it become a terrific load on the dizzy gear and timing chain. The old rule of 10 psi per 1000 rpm is really close to right.