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High oil pressure

Dan

Dan

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I am using a melling M-63 hv oil pump in my 383 and I think 90+ psi cold and 70+ hot is a little high. Is there a different spring that can be used in the relief valve that will give 15 to 20 psi lower pressure? Stock pump was 15+ idle to 40 psi hot. The reason I want too lower pressure is that I blew the O ring out of a supposedly good brand filter.(not a Pharm) lol.
If not I will go back to the stock pump.

Thanks..
 
If you have an extra spring cut a small amount off the the and have it face the cap on the pump. Good Idea?
 
Trim the spring. I've cut a 1/2 coil, twice. Pressure is still a little higher than I would like. Start by cutting one full coil. Put a piece of sheet metal between the coils to spread and protect them. Use a cut off wheel. Dremel might be better as it's smaller. My pressure is now down to 55/60@idle, 75-80@7000 hot with 5W30. I'm going to cut at least another 1/2 coil.
Doug
 
Dan said:
I am using a melling M-63 hv oil pump in my 383 and I think 90+ psi cold and 70+ hot is a little high. Is there a different spring that can be used in the relief valve that will give 15 to 20 psi lower pressure? Stock pump was 15+ idle to 40 psi hot. The reason I want too lower pressure is that I blew the O ring out of a supposedly good brand filter.(not a Pharm) lol.
If not I will go back to the stock pump.

Thanks..
Click to expand...
I'd go back to an OE style pump that puts out the correct flow and pressure, I'd find it hard to believe that the engineers at Chrysler got it wrong. The reason you blew the o-ring out was because the pump tried to achieve it's flow goal, couldn't and built severe pressure in the filter. Everything after the filter was restricting it's flow capability and unfortunately the filter acted as the weakest link. Forget cutting springs - the last coil wrap is formed flat to fit against it's mounting surface and channel the compression evenly across all coils. You may or may not get away with cutting it but just look at the way valve springs are designed to seat squarely. Besides, who wants to guess at oil pressure sustained by cutting a pressure relief spring. Sounds down right cheap and redneck unless your engine is of no value - how much does an oil pump cost anyway? Are you sure there isn't something else going on here like a partially plugged oil gallery just after the pump? A lot of people aren't aware of how much stress is put on that small tab at the pump and gear on the oil pump drive rod that runs some of these high pressure/high volume pumps. Snap that or chew the gear up and it won't just be a replacement oil pump you're paying for. Many pumps require a different type of rod and gear composition to drive them, after all they are a positive pressure pump with little to no fluid slippage.
 
Last edited:
I've cut springs and added shims to get the pressure where I want it on old and new engines. It works fine no issues ever.
 
Yatzee said:
I'd go back to an OE style pump that puts out the correct flow and pressure, I'd find it hard to believe that the engineers at Chrysler got it wrong. The reason you blew the o-ring out was because the pump tried to achieve it's flow goal, couldn't and built severe pressure in the filter. Everything after the filter was restricting it's flow capability and unfortunately the filter acted as the weakest link. Forget cutting springs - the last coil wrap is formed flat to fit against it's mounting surface and channel the compression evenly across all coils. You may or may not get away with cutting it but just look at the way valve springs are designed to seat squarely. Besides, who wants to guess at oil pressure sustained by cutting a pressure relief spring. Sounds down right cheap and redneck unless your engine is of no value - how much does an oil pump cost anyway? Are you sure there isn't something else going on here like a partially plugged oil gallery just after the pump? A lot of people aren't aware of how much stress is put on that small tab at the pump and gear on the oil pump drive rod that runs some of these high pressure/high volume pumps. Snap that or chew the gear up and it won't just be a replacement oil pump you're paying for. Many pumps require a different type of rod and gear composition to drive them, after all they are a positive pressure pump with little to no fluid slippage.
Click to expand...
 
The cut end of the spring goes toward the threaded plug. Yes it works w/o failure. This is the "Sounds down right cheap and redneck unless your engine is of no value"
Home built 9.02/151@3350lbs.
Doug

E33.jpg
 
Dan said:
Is there a different spring that can be used in the relief valve that will give 15 to 20 psi lower pressure?
Click to expand...
Isn't that going to open the relief valve, thus bypassing the filter and if so, isn't that a bit counter productive?
 
wagonman said:
The OE pump should have one of the red ones, Correct??
Click to expand...
OEM was red. aftermarket may be blue, pink, black, etc, but they will yeild 50-55psi. stock reds were 45psi. i use an HV pump with a stock type spring on one of my engine, works fine.
 
My motors run 70 psi hot 50 - 55 at idle, some people say that's high but I ran my 340 to 7600 and never had bearing problems. People also tell me I only need 45psi hot any more than that is just wasting HP.
it's not a sbc.
 
brian6pac said:
My motors run 70 psi hot 50 - 55 at idle, some people say that's high but I ran my 340 to 7600 and never had bearing problems. People also tell me I only need 45psi hot any more than that is just wasting HP.
it's not a sbc.
Click to expand...
the problems isn't bearings; it's breaking the intermediate shaft and at least eating up the shaft's bushing. HV pumps with high pressure springs are only practical for bottom end bleeders.
 
.003 on mains & rods, always run MP shafts and have never broke anything. 340 4 spd in 70 cuda 11.80 115mph 7600 rpm, built motor in 77 ran it at the track & on street for 30 years. Went trough it about 5 times and the last time was in 2005 still had the original bearings I put in in1977 and the looked like new. Clevite 77 babbitt.
 
Dan said:
I am using a melling M-63 hv oil pump in my 383 and I think 90+ psi cold and 70+ hot is a little high. Is there a different spring that can be used in the relief valve that will give 15 to 20 psi lower pressure? Stock pump was 15+ idle to 40 psi hot. The reason I want too lower pressure is that I blew the O ring out of a supposedly good brand filter.(not a Pharm) lol.
If not I will go back to the stock pump.

Thanks..
Click to expand...
What weight oil are you using ?
 
Remember, oil pressure is simply resistance to flow. Rule of thumb is 10 psi per 1000 RPM. More is not necessarily better.
 
Ranger16 said:
Remember, oil pressure is simply resistance to flow. Rule of thumb is 10 psi per 1000 RPM. More is not necessarily better.
Click to expand...
exactly! pressure is not an indicator of flow/volume; the opposite.
 
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