High Volume Oil Pump

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circlepilot

circlepilot

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I have a new (out of the box) Melling High volume M66HV oil pump for my 1965 225 slant six. I installed the pump in my engine, that has a new Hughes High lift racing cam, using the proper bolt torque (200 inch pounds) and moly paste on the gear. The cam shaft is not connected to the crank so I can spin the cam shaft. As the cam is turned it feels as if the cam gear and the pump gear are "binding" in one spot. It is free for about 270 degrees, and then gets hard to turn until it passes that one spot and becomes free again. I pulled the pump and installed the old pump. The cam and pump turn real smooth with no issues. Something else to add. The original pump housing is cast aluminum and the new Melling pump is cast iron, it also has one less bolt hole than the original pump. I'm building this engine pretty much in line with the "Doug Dutra book." His book recommends using the drive gear off of the old pump, as there has been gear failures on the after market pumps. What say you all???
Norm

oil pump.jpg
 
Good thing you found that problem now. Get rid of the high volume pump, it’s not needed
 
Here be da deal der. The slant six doesn't need an HV pump. Not only that, it gets worse. They put such a heavy load on the camshaft gear that many, many gear failures have resulted. Mostly oil pump drive gear failures, but, as you can imagine, when the oil pump drive gear fails, it takes out the cam gear, so you get two for the price of one.

The original slant six oil pumps had 5/8" deep gears. All the aftermarket replacement pumps have 7/8" deep gears, so you're gettin a "better volume" pump with the standard aftermarket pumps. What I've been doing is getting the aftermarket standard volume and adding the big block high pressure spring. They interchange with the slant 6 springs and give a pressure boost, without putting the undue stress in the camshaft and oil pump gear that the HV pumps do.

Lets get @Charrlie_S in on this. He can tell us if I've gotten anything wrong on this, but I think it's pretty much accurate.
 
does the hv oil pump spin freely out of the engine?
have you checked for runout on the hv oil pump shaft and the cam shaft, too?
If everything is running true, and it still binds, I would definitely not use it.
 
rustycowll69 said:
does the hv oil pump spin freely out of the engine?
have you checked for runout on the hv oil pump shaft and the cam shaft, too?
If everything is running true, and it still binds, I would definitely not use it.
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Yes it spins freely, I'll check the run out tomorrow. A lot of what has been posted tonight has managed to make me do some further research. What I have found has backed up the comments with something in common. "You don't need a HV pump to go racing." The HV pump may also be due to my "old school mentality" that has cropped up several times during this build. In the end...a stock pump is in the making, too bad though as the HV pump wasn't all that cheap.
Norm
 
Use old pump and sell the new one...after finding the burr on the gear. Does the new pump spin freely?
 
A high volume pump is not necessary on a slant six. It just puts extra load on the gears. If you feel the need for a hv pump, you probably have excessive clearances in the engine. I have run full groove mains, and a turbo ( which required 1/2 gal oil flow per minute), with 10-30 oil, with no problems. As stated a stock replacement pump or oem for a 81 up pump for a hydraulic lifter slant, is a high volume pump compared to the early oem pump.
 
circlepilot said:
I have a new (out of the box) Melling High volume M66HV oil pump for my 1965 225 slant six. I installed the pump in my engine, that has a new Hughes High lift racing cam, using the proper bolt torque (200 inch pounds) and moly paste on the gear. The cam shaft is not connected to the crank so I can spin the cam shaft. As the cam is turned it feels as if the cam gear and the pump gear are "binding" in one spot. It is free for about 270 degrees, and then gets hard to turn until it passes that one spot and becomes free again. I pulled the pump and installed the old pump. The cam and pump turn real smooth with no issues. Something else to add. The original pump housing is cast aluminum and the new Melling pump is cast iron, it also has one less bolt hole than the original pump. I'm building this engine pretty much in line with the "Doug Dutra book." His book recommends using the drive gear off of the old pump, as there has been gear failures on the after market pumps. What say you all???
Norm

View attachment 1715741964
Click to expand...
I don’t know if Doc covers this in his book, but I learned this from him. And that is to use gear checking paste, same yellow paste used to check the gear pattern on a ring and pinion to determine if the oil pump gear drive is centered on the cam helix. Basically put the paste on the cam drive, install the oil pump, turn the cam to drive the oil pump and then remove the oil pump and inspect the pattern on the oil pump gear. The pattern needs to be centered on the oil pump gear.
 
I believe people who are building a car and want more power always go to HI volume everything. That’s just what you do, right? They don’t know why. The old saying more is better, well it is not better at all.

you don’t need 80 lbs oil pressure or 20/50 oil in everything.

It’s directly related to bearing clearances, if you don’t know them, then what?
 
Charrlie_S said:
A high volume pump is not necessary on a slant six. It just puts extra load on the gears. If you feel the need for a hv pump, you probably have excessive clearances in the engine. I have run full groove mains, and a turbo ( which required 1/2 gal oil flow per minute), with 10-30 oil, with no problems. As stated a stock replacement pump or oem for a 81 up pump for a hydraulic lifter slant, is a high volume pump compared to the early oem pump.[
Click to expand...
I have .0015 on the rods and .002 on the mains, end play at #3 is .002 and my end play on the rods vary between .008 and .012.
 
rustycowll69 said:
sounds good except for crank end play. I don't know the FSM specs, but as a machinist, 0.002" seems too tight.
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These are the specs I'm working with. I believe I'm interpreting it right...#3 main bearing is the one with the "flanged inserts." I guess you would say I'm right at the minimum clearance at .002, however I took that measurement without "tapping the crank" a little with a dead blow. But I'll check it again.

end play.jpg
 
Regarding the HV oil pump...It's not "cut and dried" about using the HV pump vs a stock pump, but just for "s**t's and grins," I pressed the gears off both the new pump and the old pump and swapped them out. Reinstalled the HV pump with the old gear...turned the camshaft and it was smooth with no sign of binding. Go figure! Bad quality control on the new Melling HV pump???
 
Probably a burr on the new gear then
I chipped a couple of teeth on my original oil pump gear in taking it off. I have a new std volume cast iron body, pump sitting here for mine. It's new but old stock, still 6 bolt mount. I also have the original pump housing cleaned up like new, after the dunk in the ultrasonic cleaner. I have a new Melling rebuild kit for the original one, that's probably older than the engine itself (and that's a 74!) Just missing the woodruff key/ but the original pump as built by Mopar / as well as the New one (sealed power brand I believe) don't have a woodruff key in them! I also have a NOS Mopar oil pump gear sitting here too. No key slot. Would it really hurt putting in the kit and not assembling it with a key? My son works at a steel mill,and he went thru every woodruff key they had and couldn't come up with the right one.
 
I've seen several different pumps, but I haven't seen one with a key. something I have noticed, while researching all of the information about slant six pumps is...there doesn't seem to be any aluminum case pumps out there for sale, like the one on my engine. All the ones for sale are cast iron. No big problem, but where did the aluminum case pump come from...is it factory? I'm also looking at pump repair kits also.
 
The OE slant in the 83 D150 had an aluminum oil pump body. And I pulled a slant from an 87 D150 at the local pull a part and it had an aluminum oil pump body.
When I rebuilt the 83 slant I put a cast iron oil pump on it. That heavy truck will never know the difference. I put the aluminum body oil pump on the slant in the 68 Barracuda that I drag race. Saves a few pounds.
Concerning the NOS oil pump rotor shafts with keys in them. I also have found those on NOS slant oil pump rebuild kits purchased on e bay. Measure the diameter of the shaft and the ID of the gear. If there is a thousand or so of interference it will be fine. I have that same condition on the oil pump currently in use on the slant in the 68 Barracuda. I had found the shaft without a key and the shaft with a key to be the same diameter. But measure your stuff so you know what you have.
 
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On my original pump when I dismantled it there was a busted ear on the pump cover, split in the middle of a bolt hole. I was able to get a new cover (new/used) from slantzilla, a regular on the other site. It had some light scoring on the inside, where the old gears had rested against them, was able to have my kid take it to work and get 98% of it out with a shave of a few thou. Just a wee little bit left, what looks right in line with the shaft itself. No scoring within the original case on the pump walls behind where the outer rotor would ride with the replacement kit it'll be more than fine.still not sure whether I'll use it or the replacement Sealed power cast iron one I have. Weight wise since the engine is destined for a truck, I ain't worried about that last ounce of lightness.
 
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