Re-Rebuilding the 440-493 in a 1970 Charger

[1 Wild R/T]

I found this out the hard way as well when I replaced an hv with std without thinking much of it.
My warm psi is much worse than you report. I put an hv back on it and we'll see how it is this weekend

How loose are your bearings? Oil is getting out somewhere...

 

[furious70]

How loose are your bearings? Oil is getting out somewhere...

I didn't build it. Psi was just fine but the pump body itself starting leaking externally. I thought the same things dog did so I bought a std pump.
Intentional or not, the engine needs the hv at low rpm for pressure.

 

[4406bbl]

First I would temporarily attach a calibrated master gauge, compare it to your dash so you know if the dash is close to truth...
Second high volume pumps have been known to pump most of the oil up into the top of the engine quicker than it can find it's way back to the pan.....

I would not worry too much about pumping the pan dry with a big block and shaft rockers. Powell machine has a u-tube video debunking this for most engines. Even with bearing clearance at .002 I could never get by with a standard pump....you need about 10 psi per thousand rpm. I would not leave it like that, might be fine for cruising but not high rpm gear banging.

 

[1 Wild R/T]

I would not worry too much about pumping the pan dry with a big block and shaft rockers. Powell machine has a u-tube video debunking this for most engines. Even with bearing clearance at .002 I could never get by with a standard pump....you need about 10 psi per thousand rpm. I would not leave it like that, might be fine for cruising but not high rpm gear banging.

Back in the late 70's I experienced it... 383, over 6K rpm's & the oil pressure dropped to the point the idiot light came on & the gauge confirmed it... Shut it down, a minute later fired it up & the oil pressure was fine....

The engine had a Crower 280 duration 500 lift cam & kit, hooker headers, a Torker & a Holley, HV pump & hardened drive... And probably not enough pan...

In the modern day Edelbrock heads have a lot less drain back than OE heads....

If the bearing clearances are loose you lose oil in the crankcase, it quickly returns to the pan... If it winds up in the heads that's when you can have problems...

 

[4406bbl]

You would think on a big block it would be pretty hard with only one cam bearing feeding oil, unless the cam is grooved. Stock pan and thick oil maybe.

 

[RemCharger]

I would not worry too much about pumping the pan dry with a big block and shaft rockers. Powell machine has a u-tube video debunking this for most engines. Even with bearing clearance at .002 I could never get by with a standard pump....you need about 10 psi per thousand rpm. I would not leave it like that, might be fine for cruising but not high rpm gear banging.

It's possible as mentioned, to to run into a lack of pressure at high rpm, resulting from not enough lubricant at the oil pickup point.
Done it myself. My buddy and I could hear my lifters. This was 30ish yrs ago. Found the solution and have never had that occur again.
My daughter now runs and wins with a 6700 rpm 383 w/187 pan.
Have had some race engine failures.. but certainly not from oiling issues.

 

[Kern Dog]

I have a 6 quart Hemi pan, the stock 3/8" pickup and a windage tray. Cold pressure is quite good but drops like a rock once the engine warms up. I'll have to look at the pressures with the engine at high rpms. The 10 psi per 1000 rpms just seems low to me but when I had Chevys, that was common. My first 440 in 2001 idled at a 40 psi number when warmed up and hit 75 as I shifted at WOT. I thought that was high but was told that Mopars with high volume oil pumps give numbers like that. I'm just stuck on that being the standard.

 

[OKDart]

I think you're alright with the stock pump, but I prefer high volume/standard pressure (50-60 psi?) pumps with a 6 qt pan. I think years ago high volume only came with high pressure springs, but now they have both.
I have lost oil pressure momentarily with a stock pan and HV/HP pump. I was at 5-6000 RPM on the highway and glanced at my gauge and it was fluctuating. Turns out I was a quart low, but it got me thinking that there's normally only a quart in the pan at that RPM, and too slim of a margin.

 

[Nxcoupe]

Back in the day, we used to shim the relief spring and it fixed the issue without pulling the pump. Sometimes they would stick and I'd have no pressure in a couple rare instances. Had to pull that piston out and clean it, then it never did it again. They also used to sell stiffer relief springs, but the washers were a dime each. Lol.
Yes, some oils thin faster than others. I always run 10w40 or 50 in the summer on my big blocks.

 

[eldubb440]

has the pressure slowly diminished? or has it been the same since the rebuild?

 

[BSB67]

KD, refresh my memory, since posting about the lower oil pressure, have you switched or shimmed the relief spring?

 

[4406bbl]

I have a 6 quart Hemi pan, the stock 3/8" pickup and a windage tray. Cold pressure is quite good but drops like a rock once the engine warms up. I'll have to look at the pressures with the engine at high rpms. The 10 psi per 1000 rpms just seems low to me but when I had Chevys, that was common. My first 440 in 2001 idled at a 40 psi number when warmed up and hit 75 as I shifted at WOT. I thought that was high but was told that Mopars with high volume oil pumps give numbers like that. I'm just stuck on that being the standard.

That is typical of what I experienced since the 70s with melling high volume pumps, I would not be happy with what you have either. It could just need a stiffer spring or the 440 source adjustable oil pump relief plug replacement. Fwiw my hellcat idles at 65-70 cold 45 at 212, 65-70 on the highway and has hit 80 wide open thru the gears with above 200 oil temperature. 0-40 pennzoil, our scatpack runs about 10psi less. I would not be happy with less than 70 with my big block hot at high rpm, I guess mopar agrees with that on the modern hp v8.

 

[Cranky]

@Kern Dog Yup, I would confirm your gauge is accurate and go from there. And you can shim the pressure relief valve to increase pressure some. What weight oil are you using again? If you are using something like a 10w-30, you might up it to a 20w-40. You're in a warm climate and the 10 stuff isn't needed.

 

[furious70]

Shimming might not always do what you want.
Specific to mine at least, low rpm psi needed a lot of help and the hv pump does that without a corresponding increase on cold start and higher rpm. For example mine was running as low as 12psi at hot idle but 80psi on cold start up with std pump. I did not want to shim it in that case.

 

[Kern Dog]

has the pressure slowly diminished? or has it been the same since the rebuild?

I'll have to go back and look at my notes or even through this thread.

KD, refresh my memory, since posting about the lower oil pressure, have you switched or shimmed the relief spring?

I did pull the spring from the last oil pump I had. Posts 798, 831 and 833 I mentioned this.

My reason for suggesting the bypass spring swap was that in the last couple of years we’ve had a couple of builds that got new Melling HV or HP pumps that had lower than expected pressure.
For those builds, swapping the spring solved the issue.

AFAIK, the HV & HP pumps are supposed to come with the same spring, so if they were both supplied with the “correct” spring, there would be no change in pressure from swapping the spring.

If the spring doesn’t get the pressure to the desired point....... then a swap to a HV pump will be required.

On my 383, an original high mileage Mopar pump with the stiff spring provides about 35psi at 11-1200, and 80psi going down the track.

The pressure I am getting now matches what I had back after I swapped in the purple spring. It has not dropped. THIS is the first long drive that I have been on since the rebuild. I had under 700 miles on this engine before this past weekend. I do have the thin oil and mostly drive the car in the Spring, Summer and Fall.

 

[1 Wild R/T]

Thin oil gets oil to all the flow restricted areas quickly so it reduces start up wear & may help fuel economy... But with looser bearing clearances and fully grooved main bearings both of which are commonly used in high performance engines it can lead to low oil pressure... I'd be trying some 20W-50...

 

[PRHeads]

I'd be trying some 20W-50...

Yup

I’ll add that I’d have no reservations about running a HV pump in KD’s combo.

If the thicker oil didn’t get me where I wanted to be, I’d slap a HV pump right on there.

Under 40psi in a performance build BBM at cruise is lower than I’d like to see.

As for cold start oil pressure…….. on a cold start at a “high idle” warm up type rpm(1800-2000ish) my own BBM engines are usually over 100psi during those conditions.

 

[Kern Dog]

Cold start. Barely idling over 1000.

Using this oil.

Warmed up a little bit.

Now at operating temperature. Forgive the blur… the phone was touching the steering wheel and it vibrates a bit.

It drops below 40 but on the road at idle it hovers around 20.
At speed:

Over 50 at 3000 is okay but then….

By 4000 it is maybe 55? It peaks there. Pressure didn’t go any higher when I pushed to 5000 rpms.

 

[Kern Dog]

I bought a Melling High volume pump last night, today I bought this:

I had better pressures before the rebuild. Same specs on the oil clearance of the rod and main bearings. This is the standard volume pump though. I need to change the oil anyway so I’ll do so and report back.

 

[OKDart]

That is typical of what I experienced since the 70s with melling high volume pumps, I would not be happy with what you have either. It could just need a stiffer spring or the 440 source adjustable oil pump relief plug replacement. Fwiw my hellcat idles at 65-70 cold 45 at 212, 65-70 on the highway and has hit 80 wide open thru the gears with above 200 oil temperature. 0-40 pennzoil, our scatpack runs about 10psi less. I would not be happy with less than 70 with my big block hot at high rpm, I guess mopar agrees with that on the modern hp v8.

There’s a video on YouTube where a guy tries to get to the bottom of the dreaded “Hemi Tick”. He found that the Hellcat is the only Hemi using a high volume pump. All others 5.7, 6.4, etc use a pump with thinner rotors and could starve lifters of oil while idling for long periods.