The Stovebolt Site Forums The Shop Area Engine Shop 60 PSI oil pump for 56 235 motor?

I was reading on line at inliners.org/ they had a tech tip for doing a full pressure oil filter change over. At the end of the article he mentioned the pressure would be 60 psi when cold and at hwy speeds and 30 psi at idle. Is there a pump that puts out hat much pressure? For my 1956 car motor only a 35 psi was listed. The truck motor was 45 psi.
Thaanks Sharon

35 psi for the car is probably due to the fact it has Hydraulic lifters. The hydraulic blocks have have larger oil passages and divert more oil to the cam and lifter assembly. The trucks would have mechanical lifters. My service manual shows the later 58-62 engines only running at 35 psi also. All the 58-62 blocks were drilled for hydraulic lifters regardless if it was a hydraulic of mechanical application.

I have a 58-62 235 engine that has hydraulic lifters and was drilled out for the full flow oil filtration. It pegs my cab 30 psi gauge. I need to add an inline 100 psi gauge to see what the oil pressure is.

the gauge in the full pressure trucks only goes to 60 psi. I may be wrong, but I am pretty sure the relief lifts at 45 psi. The GMC oil pumps are set at 60 (?) however.

Would it be ok to put a 60 psi pump in my car/truck engine? It runs 25 to 30 psi hot on the hwy.
Thanks Sharon

I don't know if there is such a pump. Your pressure doesn't seem like a problem to me.

Well it's got 3,000 miles on the rebuild. I just won't worry about it. Daily driver just keeps on truckin.
Sharon

yep that's about what they run.

Pumps do not make pressure, pumps create flow. The passages and restrictions create pressure.

Melling and many others sell HIGH VOLUME pumps.. the gears that move the oil are longer giving more displacement per rotation.

So yes, you can get a high flow pump and increase the system pressure. It won't lube any better, and may actully be detrimental as some parts are splash lubed.. to much pressure may alter that.

Typically 20-30% GPM flow increases are what you find for high volume pumps.

Correct, the pressure is determined more by the bearing clearances, or as has been mentioned, a restriction to flow, than anything. The tighter the clearances, the higher the pressure.

There is no high volume pump for the 235 - the factory (and Melling replacement) 1955 pump is the largest, and with some work can be retro-fit into earlier engines.
The pump pressure is whatever the relief valve spring says it is, or less.

GMC oil pumps will physically fit, they have 60 PSI relief settings, and are quite a lot larger than the chevy pumps. You would probably need to fabricate your own oil lines and pickup. I am not certain of the volume, but it appears to be big enough that you might actually get or approach the relief setting. All the old hot rod manuals say to use them for more oiling. But unless you are turning it 5000 RPM it really won't be necessary.

In my L134 Go Devil you can change the relief pressure (and to a point, system pressure) by shimming the relief spring in the pump.

I'd still stay within specs as increasing pressure does not necessarily increase flow.

Someone said CAM bearings can cause low pressure... I believe that its mostly main and rod bearings. Cam bearing generally don't wear nearly as fast as anything connected to the crankshaft.

Also, as noted, using a heavier weight oil will bump pressure up... but again, you really want FLOW... a thick oil may read as high pressure on the gauge, but not be flowing anywhere near as fast as needed.

Stick with 30 weight oil, the book says as long as you read a non-zero number (like 2-3psi) at idle you are good. If it drops then consider new main/rod bearings as they are the real culprit.