Increased high volume oil pump options

[Will L.]

I looked, but am bad at finding old posts. It has been too many years since I was modifying these oil pumps.
I know the stuff about die grinder work on the ports for under the 4wd adapter/ and the block itself getting the port edges smooth & rounded over.

But I can’t remember or find my notes on the oil pump itself. When you refinish (sand down) the surface of the gear plate or body to tighten the clearance- or refinish the gears to open it up.
But what clearance spec?

What was the shim thicknesses for bumping pressure? I can’t even find where there was different colored springs and where to get them. Apparently 25 years is a bit too long.

Any help is appreciated.

 

[ak diesel driver]

Apparently there are 3 different pumps available now. Standard ,HV,and an even higher volume.

 

[jrsavoie]

I looked, but am bad at finding old posts. It has been too many years since I was modifying these oil pumps.
I know the stuff about die grinder work on the ports for under the 4wd adapter/ and the block itself getting the port edges smooth & rounded over.

But I can’t remember or find my notes on the oil pump itself. When you refinish (sand down) the surface of the gear plate or body to tighten the clearance- or refinish the gears to open it up.
But what clearance spec?

What was the shim thicknesses for bumping pressure? I can’t even find where there was different colored springs and where to get them. Apparently 25 years is a bit too long.

Any help is appreciated.

In.the early 2000s - I believe it was Tommy used an oil pump out for a 1997 or 1998 squirter block on.the engine in the 1996.

 

[Will L.]

Apparently there are 3 different pumps available now. Standard ,HV,and an even higher volume.

Any info on what brand, part number, or who makes it or sales it?

So far Summit & Jegs say no, just these two. It’s important for buyers to knkw the difference on non squirters vs with because the sales people at both didn’t understand the difference- they just say normal or hv and don’t understand the hv was stock for piston oil squirter blocks. Trying to get through to melling next but no luck yet.

 

[Will L.]

Also while I’m thinking about it- Im hoping someone makes a steel retainer piece on the oil pump drives like they do for sbc, bbc oil pump drives.
Does anyone know any secrets like if one of those, a ford, etc will work?
Our lifters btw are same a some fords.
Whats gonna happen at some point is these parts supply willDry up or be only from am general and yall don’t wanna know what happens to the price when that occurs…

 

[Will L.]

Ok, got off phone with Brian in the Melling Tech Support.
They still only offer the two pumps, standard and HV. Then the different pickup tubes for the 2 different pan.

He said:
gear end play spec is 0.004-0.008
Gear : housing side is 0.002-0.005
Tighter the better for increased efficiency & volume.
The plastic guide piece is supposed to come with new pumps but if ever needed part # is
M-55024 And unfortunately no metal options made.

The pressure piston is a one off. The spring for the HV pump is M-77030 and is the brown spring used in the Billet high volume big block Chevy pumps. There is no higher pressure spring made. But remember: high spring pressure doesn’t mean higher oil pressure - that is the point the pump will bypass. The spring pressure in the BBC billet pumps is rated 80-85psi - however speaking to them in the past a guy said he found notes that it holds to 90 psi in our pumps (probably because of the piston design).
So if you are building an engine where you are ok with a lower pressure maximum- you can order softer springs for it and free up some HP.
The general rule of thumb in gasoline HP engines is 10psi for every 1,000 rpm. So theoretically we should never need above 50 psi unless you are in runaway. No way can I condone 6,000 rpm that I once pushed. I had full scatter shields and used it & did damage (all be it minor) to the racetrack from it.

Because we loose pictures here time to time:
M255HV-294S
M= Melling. 255 series pump is 6.2&6.5 engine. -294S is pickup truck pan. -295S is Hummer pan which is slanted from front to sump and holds more oil volume.

If you order a pump without the -294/295 you are getting pump only and no pickup tube.
This is a MISTAKE imo. The tubes are known to come out. Jb weld, braze, make a bracket but always do something to retain the pickup tube because they fail. Remember to remove the piston when welding it. Reuse of the pickup tube is almost a certainty for it to come loose.

 

[Will L.]

Sorry, I forgot the stock part number of
M255294S
This is what came stock in all the piston oil squirter blocks.

The M255HV294S is the one that is 10% more volume and a higher pressure spring.

SO THERE IS 3 OPTIONS
6.2 and non squirter
6.5 with squirter
6.5 with squirter high volume & higher pressure.
Melling has offered the HV pump from the time they made the squirter model.

The maximum allowed pressure spec is 94psi, but is supposed to be 80 psi.

Then this link just texted to me:

Oil pump oddity

So my buddy recently refreshed his 6.5 and we noticed something odd. They show a standard volume pump without a spacer and then a standard volume pump with a spacer and finally a high volume pump which also has a spacer. Turns out the gears on both pumps with spacer are the same and...

www.thetruckstop.us

 

[Twisted Steel Performance]

The M255HV294S is used in the P400's due to the different oil flow in the girdle compared to others.. ... The spacer is machined for even taller gears.. I shim the spring a bit myself...

 

[Twisted Steel Performance]

Normal HV spacer plate & the P400 spacer plate... both spacer plates are the same thickness...

 

[Will L.]

Thanks Chris.

I just realized in post #4 the picture I posted that has the picture. In the picture is some texting notes that didn’t all come through. Please ignore them- it is misleading how it shows up in the pic.

 

[MrMarty51]

So a person is rebuilding a non squirter 6.2, or 6.5 if on is made in 6.5, is it wise to use the squirter style pump on the non squirter enjun block ?
Or will the squirter type pump fit the non squirter engine block ?

 

[Will L.]

Well- going higher volume or higher pressure or both adds more load to the oil pump drive & camshaft gears and this of coarse consumes power from the engine.

I hear people say “50 HP LOSS!” But when i was running sbc hotrods I went from stock to hv/hp and never saw a 10hp loss iirc that was a 350. A good friend at same time tested his 427 bbc and saw 8hp loss. And we saw huge pressure increases- like an extra 40psi range.

Then after that we pulled apart the engines and did the rebuilds. There’s a lot that people could and should do to help when rebuilding.
Remember that it’s oil flowing through that helps. That 10,50,90 psi isn’t what helps. 90psi doesn’t withstand hundreds of pounds of force from the piston shoving down the cylinder. Its the oil film wedged between the bearing and the crank, or bearing and camshaft.

You open up the ports to flow better, to flow a higher volume of oil so that cooler oil is against it and carrying away the heat.
Much of the changes I been doing to 6.5 for years is what I learned to do from SBC gassers. Ed smith down in Arizona, Denny Williams of Skull Marine out here, Ed Pink… these 3 of are the guys more well known I learned from how to build engines from. A bit of impact from trading ideas with Gale banks & John Force and two of his guys… one who taught me how to do the nitropropane.

So I don’t leave the oiling systems stock. Stock does ok, most of the time so long as nothing goes haywire. But even a mostly stock engine that I am doing for myself of family- I am opening up the holes from cam feed journal to the cam bearings and cam journal to the main bearings. Of course the bearing holes get it also. Same for wrist pins.
Their larger holes means more oil flows through. That means the oil pump has to supply more- so higher volume. That load is a tiny bit harder on the cam to oilpump drive gears. That’s ok because I make a bleeder cut to feed more oil there too.
I don’t enlarge the oil squirters. But the increase in oil supply and higher pressure means more oil goes through that same size hole thanks to Boyles law. So now more oil gets up to the bottom of the piston for cooling & to the wrist pins.

An example-I drill the 3 middle main cam to main journals to bit G size. Then the bearing to size H which is 50 thou larger so oil cant push behind it and cause a spun bearing. I drill all 5 holes from cam journal to cam bearing same way. All 5 cam bearings can use better oiling. But the 3 mains in the middle have 2 rods they supply while two end mains only feed one connecting rods each. The real is already large than the front because of the way the rear main seal works.

Look in the pic and you’ll see main 1&2 and see the larger drilled hole. Both chamfered but not yet sanded smooth. Pic 2 shows I haven’t yet drilled the cam bearing feed, but will. You can also see I have done 1st stage of cleaning up the oil return passage of flashing and helping the ramping of that path.
I learned never work until way sore- so I stop and start again as needed. Work a bit too uncomfortable and slip up leads to recycling or inventing new cuss words.

But doing everything to really help more oil flow to and through the bearings- makes a big difference in engine life…especially when you forget to check oil level or sustained driving and the engine is running at its upper temperature for a long time.

Running very oil specifications is known as blueprinted. And it really helps so long as no sludge, no debris, no moisture gets thrown in the mix.
More middle of the specification is most common. It helps for a little more abused engine but oil pressure drops a bit. This is when increased volume & pressure helps even more. Now imagine that engine 180,000 miles down the road. The extra oil flow now really helps. Opening up the passages simply allows cooler & cleaner oil.

10 psi per thousand rpm is the rule of thumb for v8 engines. But we run MUCH dirtier oil, much higher compression, much more blow by, so many “experts” would say 80 psi is absolutely ridiculous if not stupid for an engine that will never see 5,000 rpm. I call BS. Fully stock 6.5 running 80psi=no problem imo.

I am by no means a wazoo engine builder. Chris, Nate, many others here have done excellent work and if they or others have different opinions, I say hear everyone out.
But to me- bumping up pump output 1 level is not a bad thing. Advantages outweigh negatives.

I plan to do pics before actually assembling my engine and will post it when done with each area.

 

[Will L.]

Just because the pics are here, a zoomed in pic to teach whoever…

Red arrow where bearing tab goes is never altered. See how sharp the edges are.
Green arrow you can see I “broke” the edge. Basically file off the sharp edge. Sharp edges are where cracks start, and micro pieces chip off and are debris in the oil.

Yellow shows same thing all the way around the main webs, almost the entire engine gets it. Only a few specific locations you don’t do it- but some builders do everything, everywhere.

Blue arrow (at the oil squirter port) is easily and quickly chamfered to break the edge with a large diameter drill bit or tapering bit. Low rpm, 2-3 revolutions of the bit is plenty. Very low pressure on the drill.

Then later some emery cloth or sandpaper folded over finger tip- just put fingertip on hole and twist your wrist back and forth 3-4 times on the holes. The edges just a couple simple wipes over the edge. Think of it as cleaning off the micro corners that is created.
Magical wand theoretically is a rounded over edge so small you can’t see or feel where top turns into side.
Many people don’t even bother with that secondary step. But you can use ten cents worth of sandpaper and do every part if a block and head after the edges are broke in about 15 minutes.

A third party study I read from the late 90’s said removing flashing and breaking edges would have eliminated 15% of failed engines under warranty for gm.