Oil Pump thoughts

Which replacement oil pupm would you use?

  • Standard replacement

    Votes: 15 71.4%
  • High Pressure

    Votes: 0 0.0%
  • High Volume

    Votes: 6 28.6%
  • High Pressure and High Volume

    Votes: 0 0.0%

  • Total voters
    21

live4theking

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On my 68 NYer with a stock 440. The engine has not been rebuilt, but I've had the heads off and I've done the timing chain. So, I guess the only factory gaskets are the oil pan, oil pump and fuel pump.

The oil pressure light has never came on unless the car has stalled. I put an electronic oil pressure gauge on the car. Due to the size of the sending unit I had to use a 4" nipple to install it. So, with all this said the gauge indicates about 20psi going down the road and a bit less when idling. Mind you the idiot light doesn't come on. This has me considering replacing the oil pump.

Which would you use and why? Standard replacement, high volume, high pressure or high pressure and high volume?
 
Use a standard replacement on all applications except a performance built engine. High volume pumps have an annoying tendency to suck the sump dry when and engine is cold unless you go to at least a 6 quart pan. High pressure pumps take more engine horsepower to run and have a bad habit of fracturing intermediate shafts resulting in zero oil pressure. You do not need the extra oil pressure or extra volume on a street engine. Use a Melling standard replacement pump, the are the best in the business and be happy.

Dave
 
I don’t think you need to replace it but stay away from high pressure pumps for a streetcar cruiser.
 
I just did this very thing because my pump had a tiny leak due to old, hard o-rings. I went with standard pressure and volume, replacing the old Mellings High Volume. Why? To ease the strain on the pump hex drive. This lazy 440 doesn't need a high volume unit. This did drop my "going down the road" pressure from nearly 60 to 40, which is plenty.

From Rocky:
pumppture.PNG
 
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My vote is Melling oil pump.
I did a standard in the stock 66 300 383 and high volume regular pressure in the 68 Newport hotrod 383.
 
I went with Melling high volume in the ‘70 440 rebuild simply because the builder recommended it. I would have no other reason to do it otherwise.
 
I used a Melling standard pump in the 413 in my 300J. It maintains a steady 47lbs pressure at highway speeds, even in hundred degree weather. The high pressure and volume pumps create excessive heat and wear.
 
There are "high pressure" and "high volume" pumps. You want a high volume pump. Stock replacement is fine. Good Luck
 
At what "road speed" is "going down the road"? How many miles on the motor? How much oil consumption? What viscosity of motor oil? How long since it was changed? What pressure @ 70mph in "2", rather than "D"? Or would it be easier to do 40mph in "1" instead?

20psi @ hot base idle is fine. My old '50 Plymouth service manual states that ANY oil pressure at idle is enough, fwiw.

Unless the clearance between the gears in the pump is too much or they are scored with wear, you might consider putting a washer behind the relief valve spring to raise the pressure a bit?

The old rule of thumb used to be 10psi/1000rpm, but with fuel economy and better oils, that seems to have dropped a bit, over the years. Higher oil pressure = less power to the flywheel = more fuel consumption,, plus strain on the oil pump shaft, as mentioned.

Just some thoughts,
CBODY67
 
, with all this said the gauge indicates about 20psi going down the road and a bit less when idling
Does it ever indicate more? Like when it is cold? If you rev it up to let's say 4000 rpm is it still on 20. Not a fan of electric guages.
Anyway, just use stock replacement. High pressure would be for high rpm, high load, tight clearances. High volume is for high rpm, loose clearances, full groove main bearings(all the time pressure to rods).
A pump may not fix your problem if clearances are loose/worn. They are stone axe reliable. The have more volume than usually needed which is why they are at 50 psi at 2500 rpm.
 
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Just did mine 2 weeks ago on my stock 383. Took apart the stock pump, cleaned it, new seals reinstalled. Running like it should...50psi strong.

I asked the techs at S&K Speed shop the same questions you are asking. They said only change it if you do HP motor work and high volume for street only.

The stock oil pumps on these old big blocks are very high quality in design and performance. Not prone to breaking, provide constant and consistent pressure and can take a beating.

Check it for wear, reseal it, install it and run Valvoline VR-1 10w-30. Happy days... Sorry...lol. that's my choice for oil... Use the best oil of your own liking. But Mopars love high zinc oil... Just saying.
 
Sounds like the guy's have covered all the questions John, I would verify the oil pressure with a mechanical gauge though. If it's indeed low maybe a heavier weight oil. When you did the timing chain was the nylon missing from the cam gear? I don't remember what the oil pickup is like on the big block, but I have seen plenty of oil pickups plugged with nylon from cam gears
 
He has a '68. Do they have nylon gears?
Did 1966 big blocks have nylon gears? When did Mopar start using them?
 
Not 100% sure when they first used the nylon coated gear

My recollection is that the plastic gears first appeared on the 273 in 1965. My '65 chrysler with the 383 had a metal gear as did the '64 413 in the 300. Most if not all 318 poly engines had steel gears. Mopar started transitioning to plastic faced gears with the '66 model year, some engines had them some did not. By '67 nearly had plastic faced gears. On the big block engines the plastic gear can be seen by removing the distributor and looking towards the front of the engine with a flashlight.

Dave
 
Sounds like the guy's have covered all the questions John, I would verify the oil pressure with a mechanical gauge though. If it's indeed low maybe a heavier weight oil. When you did the timing chain was the nylon missing from the cam gear? I don't remember what the oil pickup is like on the big block, but I have seen plenty of oil pickups plugged with nylon from cam gears

He has a '68. Do they have nylon gears?
Did 1966 big blocks have nylon gears? When did Mopar start using them?
Yes, it had a nylon coated cam gear. Not a single bit of the nylon was missing. More and more things lead me to believe this is a 59k miles motor.

As I stated I'm suspecting that the 4" nipple I had to use to install the sender maybe influencing the accuracy of the gauge.

The oil light has never came on so I'm not even sure I'll change it. Just thinking about it.
 
As I stated I'm suspecting that the 4" nipple I had to use to install the sender maybe influencing the accuracy of the gauge.

NO! The nipple has absolutely zero affect on measured pressure. Pressure, NOT flow. Nothing affects pressure, except resistance to flow. And everything affects flow. However, there is no flow in that nipple, just pressure from the oil pump after all the bearings and lifters get their share of that pressure and flow. It's like the inside of a balloon....the pressure is the same everywhere inside, even though the sad-faced-clown made it look like a French poodle....with a 4" nipple for a pecker.
 
NO! The nipple has absolutely zero affect on measured pressure. Pressure, NOT flow. Nothing affects pressure, except resistance to flow. And everything affects flow. However, there is no flow in that nipple, just pressure from the oil pump after all the bearings and lifters get their share of that pressure and flow. It's like the inside of a balloon....the pressure is the same everywhere inside, even though the sad-faced-clown made it look like a French poodle....with a 4" nipple for a pecker.
But the low quality sending unit may be in question. Agreed that trapped pressure is just that trapped, has no effect.
 
He has a '68. Do they have nylon gears?
Did 1966 big blocks have nylon gears? When did Mopar start using them?

my ‘66 Polara had a nylon gear when I tore it down after I bought it. Not sure how it was a running/driving car, but it was.

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