Need advice on Oil Pump

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3406pk

3406pk

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I'm doing rebuild on my 72 340 engine out of Challenger. Engine will be basic stock for mostly stock restoration of car for mostly cruising. Going with 70 spec .030" over pistons for 9.4 cr and w stock J heads. Anyway the rebuild kit that I got has the High Volume Melling oil pump. Oil pan is original and only mod to block is that I opened up oil passages to 7/16" per Guitar Jones post. Question is will the HV pump cause problem w stock pan. Car won't be driven in cold weather, only summertime cruiser. Appreciate advice. Thanks
 
Test fit the pan over the oil pump before installing it. It will usually prevent the bottom flange from resting flat on the block (the flat gasket surface without the gasket). It will only be like 1/8" gap. I usually then use a ball peen hammer on the inside lip of the oil pan to bang it and make some clearance for the pan. Trial and error. Pound a bit, then test fit. Pound a little more, then test fit.

I like to get it to the point where the oil pan can rest on the gasket surface of the block without the gasket. That way it will be fine with a gasket.

The melling HV oil pump is a good pump. I've put over 250,000 miles on one or two of them.
 
In my opinion, a stock pump is what you want. After all my years here, many of the "Why do I have this problem." threads are owner caused.

The wheel doesn't need to be re-invented. The wheel works fine the way it is.
 
1968FormulaS340 said:
In my opinion, a stock pump is what you want. After all my years here, many of the "Why do I have this problem." threads are owner caused.

The wheel doesn't need to be re-invented. The wheel works fine the way it is.
Click to expand...

I cannot agree any stronger with this. ^^^^^^

I will add, if you forge ahead with the HV pump, make damn SURE you get the hardened Mopar Performance intermediate shaft, or you will likely make a pretzel out of the stock one.

That said, a high volume pump won't hurt anything as long as you get the heavy duty shaft. It won't pump the pan dry. That's an old wive's tale. They do however take more power from the engine to drive.
 
1968FormulaS340 said:
In my opinion, a stock pump is what you want. After all my years here, many of the "Why do I have this problem." threads are owner caused.

The wheel doesn't need to be re-invented. The wheel works fine the way it is.
Click to expand...


Yeah, but with his opening up the oil passages, it may need to pump a little more oil to fill the extra volume of the holes. The extra capacity won't hurt you, not having enough will....


I've used the HV melling oil pumps for years and have had no problems with them. They are very reliable.
 
RustyRatRod said:
I cannot agree any stronger with this. ^^^^^^

I will add, if you forge ahead with the HV pump, make damn SURE you get the hardened Mopar Performance intermediate shaft, or you will likely make a pretzel out of the stock one.

That said, a high volume pump won't hurt anything as long as you get the heavy duty shaft. It won't pump the pan dry. That's an old wive's tale. They do however take more power from the engine to drive.
Click to expand...



Yes. I always run the heavy duty distributor shaft with them.
 
The HD/HV oil pump is not needed.
 
Yabut................here's the thing..............

It's not just oil pumps..........it's some aftermarket PANS

I bought a brand new Milodon "replacement" pan and the damn thing interferes with one pump I've got, and that pump has countersunk cover screws and appears to be a "stock" pump!!!! This is on a 360 LA.

It really REALLY pisses me off that pump / pan manufacturers cannot seem to get together on this issue.
 
Thanks all you guys for the advice. One of my concerns when engine was running was that oil pressure was low. During tear down I didn't find any real problems where oil was losing pressure unless it was cam bearings. Hopefully with all new bearings and rings oil loss will not be problem. I will pressurize with drill after assembly so can check out before installing engine. I will exchange HV for standard pump. Also good ideas to check pan fit and use HD shaft. Thanks a lot.
 
3406pk said:
Thanks all you guys for the advice. One of my concerns when engine was running was that oil pressure was low. During tear down I didn't find any real problems where oil was losing pressure unless it was cam bearings. Hopefully with all new bearings and rings oil loss will not be problem. I will pressurize with drill after assembly so can check out before installing engine. I will exchange HV for standard pump. Also good ideas to check pan fit and use HD shaft. Thanks a lot.
Click to expand...

Be absolutely certain you get all the plugs back in. One in particular that's "a trick" is a little tiny drive in plug goes up in through the rear main, up in the vertical gallery on the way up to the oil sender.

Here:

http://www.forabodiesonly.com/mopar/showthread.php?t=253707

http://www.forabodiesonly.com/mopar/showthread.php?t=103623
 
krazykuda said:
Test fit the pan over the oil pump before installing it. It will usually prevent the bottom flange from resting flat on the block (the flat gasket surface without the gasket). It will only be like 1/8" gap. I usually then use a ball peen hammer on the inside lip of the oil pan to bang it and make some clearance for the pan. Trial and error. Pound a bit, then test fit. Pound a little more, then test fit.

I like to get it to the point where the oil pan can rest on the gasket surface of the block without the gasket. That way it will be fine with a gasket.

The melling HV oil pump is a good pump. I've put over 250,000 miles on one or two of them.
Click to expand...

I wasn't aware that a modification had to be made to the stock pan to use a HV pump. I am sitting on an American made Melling M-72HV and the heavy duty intermediate shaft that I am planning on using. If this is the case I guess I will have to buy another pump.
 
Oklacarcollecto said:
I wasn't aware that a modification had to be made to the stock pan to use a HV pump. I am sitting on an American made Melling M-72HV and the heavy duty intermediate shaft that I am planning on using. If this is the case I guess I will have to buy another pump.
Click to expand...


Yeah, we had to do that when we built Cliff's 360. :violent1:
 
3406pk said:
Thanks all you guys for the advice. One of my concerns when engine was running was that oil pressure was low. During tear down I didn't find any real problems where oil was losing pressure unless it was cam bearings. Hopefully with all new bearings and rings oil loss will not be problem. I will pressurize with drill after assembly so can check out before installing engine. I will exchange HV for standard pump. Also good ideas to check pan fit and use HD shaft. Thanks a lot.
Click to expand...

If you are concerned about oil pressure, you can buy the high pressure oil pump spring from Mancini and install it in whatever pump you decide to use. Use it if you wish.


Also on the low oil pressure thing. check that there are two plugs behind the camshaft rear thrust plate. I had an engine that the machine shop left out these two plugs, it would start with 20-25 psi cold, then drop down to 10 warm. It was these two plugs that were left out that caused the problem.
 
The only time you really need the HD shaft is if you run the pressures really high like 80psi hot. As long as the pump pressure valve is working correctly it should blead off extra volume above the preset pressure. I personally have used the stock pump drive with HV pumps on my oval track race cars turning 7k plus and never broke one that's in 20 years of racing. I would run what you have and if the pressures are high when hot run a thiner oil. A little more oil running over them valve springs will help cool them and make them last longer.
 
Oklacarcollecto said:
I wasn't aware that a modification had to be made to the stock pan to use a HV pump. I am sitting on an American made Melling M-72HV and the heavy duty intermediate shaft that I am planning on using. If this is the case I guess I will have to buy another pump.
Click to expand...

My stock 340 pan clears M-72HV with no issues.
 
My 360 pan did not. It required a hammer.
 
I question the clearance on my pan while building my engine, the 340 pan I have has a slight bump, obviously factory in it right where the pan sits.

Yes I have also had to bend clearance on a 318 one time.
 
Oil pressure is more a function of clearances than the pump. You said you had low presssure - what were the clearances or were they checked? If you found no big wear on the beaings they clearances chould have been carefully checked to figure out if there was a problem.
IMO - use a stock pump with the HP relief spring from MP. With factory clearances you will have more than enough oil volume for them. There is no real change in volume when you drill the passages - it's only if the clearances allow more oil to bleed out that you will need more volume.
If the clearances are larger: .0025-.003+, or sustained high rpm, a higher volume pump is the ticket but pair it with a proper pickup. The factory pickup is the restriction on the Mopar oil system. Also - if you use the HV pumps - use the MP hardened drive. IMO you're more likely to twist the gear on the shaft than shear the hex end but the MP ones have pinned gears in addition to the tapered and hardened hex drive.
 
This has been really interesting and I now have some good tips for assembly. Thanks again. I took pictures and made diagrams of all plugs in oil passages. My memory is not good after 3 months since disassembly. lol
 
[ame]http://www.mellingengine.com/Portals/5/pdf/pdf_catalog/high-volume-pumps.pdf[/ame]

interesting read from melling
 
Stock pump for me, no need for a HV unless clearances are on the hi side. My stock idles at 25 psi and goes to 65 psi hot.
 
I haven't had any issues with the HV pumps cleaing a pan - but I use a factory cork gasket. That adds a little distance too. If you use just sealant instead of a gasket that might be why they hit.
 
I've had problems with HV pumps clearing the pan even using cork gaskets. Some HV pumps have recessed bolt heads while others have standard bolt heads that stick out. Those are the ones I always have trouble with. I'm with Moper on the pressure thing. As long as the bearing clearances aren't real loose a stock volume pump should do the job. Way back in the 70's when Mopar Perf. was Direct Connection they put out a memo that said unless you use a larger i.d. pickup the HV pump doesn't gain you much. The last few yrs. I have used stock volume pumps in everything except one race engine I built for a guy that had real loose bearing clearances. My 408 has .002" on the rods and .0025~.0028" on the mains. A stock volume pump in it runs 28 psi hot pressure at idle (800 rpm) and 58-60 psi by 2000-2200 rpm and that's where it maxes out
 
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