proper oil pressure
Postmaster
Joined: Jun 2004
Posts: 4,190
Likes: 2
From: Riverside, So Cal
The rule of thumb is 10 pounds pressure for every 1000 rpm. So, at 1000 rpm idle, you should have 10 psi.; at 3000 rpm, 30 psi. I think of this as a minimum, but have heard others say that their engines run less, especially at idle, without any trouble.
When my 351C started running 30 psi at 3200-3500 rpm, I had it rebuilt.
When my 351C started running 30 psi at 3200-3500 rpm, I had it rebuilt.
Fleet Owner
Joined: Jul 2004
Posts: 27,291
Likes: 1,055
From: NM
I tend to agree with Randy, but what's really important is the trend -- if you see it is dropping off over a period of time, it's time to do something!
I've had several cars/trucks behave like this: at steady speed, if I give it just a little gas, the oil pressure drops; if I let off on the gas (use the engine to brake), the pressure increases above the steady-state pressure. Every time an engine behaves like this, it has turned out the main bearings are shot, and so is the oil pump. Chicken or egg, the pump or the mains? Whatever. My '53 F-100 w/223 was behaving that way but pulling 30 psi at highway speed, right up until it threw a rod in Kankakee IL, on the way home from college for Christmas (20 deg. outside), with a nice-looking gal along for the ride...
I've had several cars/trucks behave like this: at steady speed, if I give it just a little gas, the oil pressure drops; if I let off on the gas (use the engine to brake), the pressure increases above the steady-state pressure. Every time an engine behaves like this, it has turned out the main bearings are shot, and so is the oil pump. Chicken or egg, the pump or the mains? Whatever. My '53 F-100 w/223 was behaving that way but pulling 30 psi at highway speed, right up until it threw a rod in Kankakee IL, on the way home from college for Christmas (20 deg. outside), with a nice-looking gal along for the ride...
Postmaster
Joined: Mar 2000
Posts: 3,730
Likes: 13
From: Waynesville, OH
Originally Posted by WALFORD'S 56
I always wondered about oil pressure readings,and think my 56 is odd.I start her up and it goes right to 65 psi.I am thinking wow great oil pressure.Is this a sthing to worry about?
Cargo Master
Joined: Aug 2004
Posts: 2,575
Likes: 36
From: Greenville, SC
My completely rebuilt 292 also runs right at 60, I put a newer pump on it and the new pump has higher capacity and thus higher pressure.
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Postmaster
Joined: Apr 2004
Posts: 3,005
Likes: 2
From: Santa Clarita
The 289 I built for my truck has a high volume pump in it. At startup, I have 70-80 lbs of pressure, at idle when cold around 60 and if it's hot, no less than 40lbs. If the pressure is too low, under 10 lbs, could a sign of the crankbearings wearing out and creating a gap between the bearings and crankshaft.
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Fleet Owner
Joined: Jul 2004
Posts: 27,291
Likes: 1,055
From: NM
High-volume/high-pressure pumps can cause problems! They aren't needed for street engines (even pretty hot ones) and they sap HP. I gave this lecture to my son when he was building a very hot 302 SBF, but he was certain he needed something besides stock. Two weeks after completing the engine, it blew the pressed-in front oil galley plug (behind the timing gears) out, the plug got caught in the timing chain, the crank wiped all the the journals on loss of oil, and it threw a rod thru the cylinder wall. (Note, he claims he was "not racing" -- uh huh). I have heard of other people twisting the hex oil pump drive shaft like a pretzel on cold start-up in the winter.
Imlowr2, if you have a chance, replace that pressed in plug with a screwed-in plug or pin the pressed in one! Or go back to a stock pump, they are just fine for anything under 500 HP!
Imlowr2, if you have a chance, replace that pressed in plug with a screwed-in plug or pin the pressed in one! Or go back to a stock pump, they are just fine for anything under 500 HP!
Postmaster
Joined: Jun 2004
Posts: 4,190
Likes: 2
From: Riverside, So Cal
I had my 351C rebuilt this last spring by a local rebuilder. I asked for a high volume oil pump and he talked me out of it. His explanation was that they require a larger volume pan so that they don't pump it dry at high rpm. He convinced me. Almost all of the internals (including the oil pump) are new, but it is a stock pump.
My perfomance Ford engine rebuilding book also talks about how Rousch builds his motors. He uses stock pump, and tweaks them a little for higher pressure, not volume.
My perfomance Ford engine rebuilding book also talks about how Rousch builds his motors. He uses stock pump, and tweaks them a little for higher pressure, not volume.
Postmaster
Joined: Sep 2006
Posts: 4,525
Likes: 1
From: oh
My 272 was not running for 15 years and locked up.I only have 21,000 original miles and thought that 60-65 psi was unusually high.It is clean as a whistle inside,and I am using 30 weight non detergeant oil.I heard my DAD say that is what the old trucks ran.I looked at your message board and you guys say other-wise!Should I change the 30 n.d.oil and if I do will I get a different oil press. reading? THANKS
Postmaster
Joined: Jun 2004
Posts: 4,190
Likes: 2
From: Riverside, So Cal
Originally Posted by keisha9
well i just went out cruising on the sunny day and i got different readings now.....20 psi at 1000 rpm idle and up to 60 psi when gettin on er' ...
Fleet Mechanic
Joined: Sep 2004
Posts: 1,674
Likes: 2
From: Rowland Heights
How much does filter and oil play on pressure. Talked with guys where engine warms up and pressure drops. Change to heavier grade oil and pressure is better when warm. Will changing to a steel oil filter instead of paper better. Pure Power has some pretty nice filters that last for life. Costly but might do a better job?
