How to Install a High Press Spring in a Small Block Oil Pump

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krazykuda

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krazykuda submitted a new Article:

How to Install a High Press Spring in a SB Oil Pump

Hello folks! Krazykuda here to show you how to install the MP high pressure spring in the small block oil pump. This will work for all oil pumps for the 273-318-340-360 LA engine.

Some people like to run higher oil pressure, and some don't. This is for those who choose to run a little more oil pressure than "standard" stock pumps put out. For those of you who don't buy into increased oil pressure, please move on and not leave any negative comments.

Use this information at your own risk. If not done properly, your oil pump can fail which can potentially destroy an engine. I cannot be held responsible if this is not done properly.


For this thread I will be using the Melling M-72HV high volume oil pump shown below:


View attachment 1714943111

Next you will need the Mopar Performance Spring Kit P/N P3690944:

View attachment 1714943112

Here it is shown from behind so you can see. It only has the spring and cup plug that you will need. It USED to come with a cotter pin, but they "cost reduction" that out now, so you may want to get a spare cotter pin or two in case you can't save the original one:

View attachment 1714943113

Here are a few different angles for the oil pump:

View attachment 1714943114


View attachment 1714943115

Here's the view showing the part that we will be working with. Notice how the cup plug faces inward, not outward like the cup plugs in the blocks and heads. This is important, as putting it in backward will greatly increase your oil pressure (probably WAY too much):

View attachment 1714943116

Here's the tools that we will need. Notice that there is no drill and drill bit shown. You DO NOT WANT TO USE A DRILL HERE! The chips that it generates can cause the oil pressure relief valve to stick and then there will be NO OIL PRESSURE in your engine. We want to punch a hole in the cup plug to keep from making chips that can cause the valve to stick. It only takes one chip to do it...

View attachment 1714943117

I like to get an assortment of screws and washers to handle whatever size hole I end up with and different lengths in case I accidentally drive the cup plug deeper when trying to punch the hole:


View attachment 1714943118

Here's what I use to punch a hole in the cup plug, and then use the hook on the right to help fish out the pressure relief valve:

View attachment 1714943120

Ok, now we are going to move on to removing the old spring....

Ok, now we are ready to remove the old spring.

The first thing to do is to remove the cotter pin. Pretty simple, just straighten the bend at the bottom as shown below:


View attachment 1714943121

Here the cotter pin has been removed. Note the cup plug orientation with the lip facing inward, not outward. You need to put it back together like this:

View attachment 1714943122

Next take a punch or scratch awl and punch a hole in the cup plug. You want to use a medium weight hammer with a SHARP blow. Not lightly as it will just push the cup plug deeper and not make the hole. A quick sharp blow is what you need here. Don't be afraid to give it a good whack, take off your panties and put on a pair of tightey whiteys for this....

Here's what you want it to look like:


View attachment 1714943123

Now get those screws and washers that I showed you in the first post and see if one of the screws will start in the hole. If not keep opening up the hole with the punch/scratch awl a little bit at a time until you can get the screw to thread into the cup plug like this:

View attachment 1714943124

Use one of those split interior trim removal tools/pliers/vise grips to remove the cup plug with the screw and washer. The washer helps you grab under the head easier to pry it out like this:

View attachment 1714943125

Here is how the parts all go together (and the order that they come out). Notice that the valve has a deeper pocket from one end than the other. The shallow end goes into the bore first, and the deeper part goes outward toward the spring side (the spring goes into the deep side):

View attachment 1714943126

Here I am showing the shallow side of the relief valve, this is the side that goes into the bore first, opposite the spring:

View attachment 1714943127

Here is the deeper side of the relief valve that the spring goes into. This faces outward when you assemble it.

View attachment 1714943128

Here's a side view of the relief valve. The shallow part is on the right. You have to keep this hospital clean, any chips and/or dust can make it stick. If it sticks, you will not get any oil pressure. Make sure it is free of dirt, debris, chips, and burrs and that it moves smoothly and freely in the bore when you install it.

View attachment 1714943129

Ok, now move on to the next step of installing the new spring...

Ok, now we are ready to put it back together. You have to keep everything here hospital clean. All it takes is a small chip or piece of dirt to make the relief valve stick - it has happened to me, trust me on this....


First you put the valve in with the shallow side inward and the deeper side outward toward the spring. Use a light oil to lubricate it so it moves freely. Nothing too thick that may make it "sticky" for the first start.


View attachment 1714943132

Then the spring and the cup plug. Remember that the lip for the cup plug faces inward. Here's showing how the parts go into the bore:


View attachment 1714943133

Here I gently pushed them in and just have the cup plug starting to engage the bore. You want to gently tap the cup plug to get it just past the hole for the cotter pin. Go slowly, take off the tightey whiteys and put the panties back on for this....


One step at a time. Gently tap it in a little at a time until you can just install the cotter pin. Be careful not to go too deep as this will increase the spring pressure and thus the oil pressure also. The new spring is enough, that's all we need, we don't need any more.


View attachment 1714943134

I like to use a socket close to the outer diameter of the cup plug to drive it in without affecting the "fit" by distorting it with a sharper pointed type driver...

My 11 mm 1/4" drive socket worked well.


View attachment 1714943135

Here's a top view showing that I have the cup plug just deep enough to put in the cotter pin:


View attachment 1714943136

Side view of above:


View attachment 1714943137

Here it is with the cotter pin in place:


View attachment 1714943138

Now bend the cotter pin (Sorry it doesn't show in this pic, but it is bent).


View attachment 1714943139

I like to mark the pumps with paint pen or something permanent so I know that I have the high pressure spring installed so I can keep track of them.


View attachment 1714943140

Here is a chip that fell off during our process. This one is much bigger than needed to stick that valve, all it takes is a sliver or small piece of dirt. I've seen many stuck oil pressure relief valves in my days and it doesn't take much to do it.

View attachment 1714943141

That's all there is to it. You have to make sure that you keep everything clean and get all the parts together correctly (not backwards).


That's all folks...





Here's some info that we added after some discussion that may help you:

Ok guys & gals, here's the scoop:

Mopar Performance:

Both the standard and high volume pumps come with the "stock" spring.

If you wish, you can increase the pressure with the high pressure spring kit P3690944 and it is applicable for both standard and high pressure pumps.

The high pressure spring kit is designed to target 75 psi oil pressure (it may vary from one engine to another).

The Mopar tech guy does not know who supplies the MP oil pumps if it is Mellings or not.

He also can't tell me how the Melling spring compares to the MP springs.


Mellings:

They use the same spring in both the standard and high volume oil pumps.

Their spring target runs 72 psi on a standard pump.

It will be 2-3 more psi in the high volume pump due to the increased volume will add some pressure.

He can't tell me if they supply the MP pumps or not.

He can't tell me how their spring compares to either Mopar spring.


My conclusions:

If you run the Mopar oil pumps and want more pressure, use the high pressure spring kit.

If you run the Mellings oil pumps, you don't need the high pressure spring kit, as they are within 2-3 psi of the MP high pressure spring target....



So that is the best that we can do to answer the pressure question. None of the manufacturers can tell us for sure..... :banghead: :banghead: :banghead:


Side note:

The summit racing site states:

Melling high-volume oil pumps give you an additional 20 to 25 percent of much-needed oil volume for your performance application. For those of you who need added pressure, many pumps are supplied with a high-pressure spring where noted.


What is this mark and where is located?

How do we know what we are going to get when we order it?

How do we know what we get when we open it and look at it? What are we looking for?


I think that this is wrong. How can they randomly make them one way and then change to the other on a whim? Doesn't make sense. They should all be consistant/the same...

Here's the page with the listing from Summit:

http://www.summitracing.com/parts/mel-m72hv



I think together we can figure this out.

The Mellings guy told me that they cast their part number in the housing near the mounting face. I found it on mine on the outside of the part of the housing where the pick-up tube goes in. I have a picture of it below.

If anybody has either the standard or HV Mopar Performance pumps, please look for the marks on the housing for each and post back (with pics if possible - I want accurate provable info to pass on - get the part number on the box and housing ID like shown below).

View attachment 1714970170


Read more about this article here...
 
Last edited:
Very nice Karl. You are a true asset to the site. Thanks.
 
Great info there !! Now what about us Big Block guys??. Just kidding, I know how. LOL
 
That's a great "how-to" Karl,
C
 
One thing I'll add - the HV pumps already come with the HP spring... The standard pumps are the ones that need it.
 
Very nice write up.

Have the same question though.

Is this necessary on the HV Melling pump ?
 
Very nice write up.

Have the same question though.

Is this necessary on the HV Melling pump ?

moper said they come with the HP spring. I've never seen one that did OTHER than the Melling HV pumps MP used to sell marketed as high pressure and high volume. MP would take the Melling pumps, disassemble and clearance them then install the high pressure spring package and rebox them as MP HV/HP units. Used many of them through the years. If the regular Melling HV pumps had the high pressure springs in them, it's news to me. Evidently Mopar Performance didn't think they did.
 
moper said they come with the HP spring. I've never seen one that did OTHER than the Melling HV pumps MP used to sell marketed as high pressure and high volume. MP would take the Melling pumps, disassemble and clearance them then install the high pressure spring package and rebox them as MP HV/HP units. Used many of them through the years. If the regular Melling HV pumps had the high pressure springs in them, it's news to me. Evidently Mopar Performance didn't think they did.


As far as I know the HV Mellings and MP are just the "stock" spring. You have to buy the high pressure spring and install it in the HV pumps. I've been doing it for years...


The guys at Mancini never stop me from buying the spring when I get a HV pump. Art and Tony would have told me if I didn't, they wouldn't do me that way and they knew their parts. They worked there for many years, and the guys today don't either.... I swear that there have been months that I've spent enough in there to cover their electric bill. LOL!

We need to research and find out for sure....
 
We need to research and find out for sure....

I just spoke with Renee at Melling, since they're 20 minutes from my house, I thought I'd give them a jingle.

Melling DOES NOT sell the Melling M-72HV with a high pressure spring. They sell the standard volume pump with a relief of 72 and the HV with a relief of 75.
 
That's what I thought. Rich Ehrenberg sells....or used to sell the MP high pressure/high volume pumps I talked about. I bought my last one from him about two years ago.
 
I just spoke with Renee at Melling, since they're 20 minutes from my house, I thought I'd give them a jingle.

Melling DOES NOT sell the Melling M-72HV with a high pressure spring. They sell the standard volume pump with a relief of 72 and the HV with a relief of 75.


Then they got two inquiries about this today.

Thanks for checking Bruce!
 
Yup. The ones I am talking about from MP are discontinued. Rick Ehrenberg used to sell them. They were both high volume and high pressure, just like I described. I don't know why they gotta quit makin all the good stuff.
 
Then they got two inquiries about this today.

Thanks for checking Bruce!


I kinda figured, he said "you're the second person to ask that today". I asked him if it was Karl he spoke to and he said he thought so, you got the same person I did, lol.
 
Many thanks Karl. Your time and efforts are greatly appreciated. This site has helped me more than than any single source partially due to those going the extra mile to truly help.
Darrell
 
Many thanks Karl. Your time and efforts are greatly appreciated. This site has helped me more than than any single source partially due to those going the extra mile to truly help.
Darrell


You're welcome.


Collectively, we have lots of knowledge here and good people who help each other out. That's what makes FABO the best site for Mopar info....
 
Hey all. I know this is an old post but will always be relevant. Why can't I just use the 11 mm socket on the back of the cup trick and tap it in further into the housing and then install a washer between the cup and the spilt pin?
Cheers
Tony
 
I just spoke with Renee at Melling, since they're 20 minutes from my house, I thought I'd give them a jingle.
Melling DOES NOT sell the Melling M-72HV with a high pressure spring. They sell the standard volume pump with a relief of 72 and the HV with a relief of 75.

Does a 3psi varience constitute the difference between a std spring and a high pressure one?

Sticking to the premise of providing information...
The stock spring will relieve pressure at an indicated pressure of about 55psi. That's regardless of the size of the pump's vanes... A higher volume pump will reach that point much earlier than a std volume unit because it's displacement in one revolution is 25% larger. So it's basic physics. What we interpret as pressure is resistance to flow within a system. The relief valve, being right within the pump itself, will be instantly exposed to any rise in output, and subsequent rise in pressure. Because of that, all HV pumps come with a spring that is a bit stiffer than a standard pump relief spring. Just as Bad notes above. If they didn't, the pump would open the bypass at a much lower rpm, but at the same pressure as a std pump. That's why when you take a worn engine and stick in an HV pump you get 60psi of presssure when the old pump had 35.

From another perspective - look at the relief springs themselves. The resistance in any spring is a function of the material, wire diameter, and number of coils (length). The one in the stock HV pump has 13.5 coils. There is no picture of the two springs side-by-side, or a standard stock output relief spring, but I'd wager the overall length of the MP one is a little longer, because the MP one has 14, and the stock one will be shorter, made of smaller diameter wire, and have a different number of coils. The two Karl shows are very similar which also jives with Bad's Meliing representative's comments.
 
Man ! What an informative How to, and with pics. Takes all the second guessing away and written in a way that makes it a good learning experience. The follow up information is also awesome. It certainly helped me out and answered a couple of questions that I had about my own pump. All of the feed back was really good, and it made this a great read. Thanks Guys! Glad I'm on this site.
 
Hey all. I know this is an old post but will always be relevant. Why can't I just use the 11 mm socket on the back of the cup trick and tap it in further into the housing and then install a washer between the cup and the spilt pin?
Cheers
Tony
this is my first time reading this & that crossed my mind also!
 
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