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BBC M77 Oil Pump

11K views 52 replies 20 participants last post by  shovelrick 
#1 ·
Im pulling the new M77HV out of my new 489 and installing a new M77, it came with a black spring (high pres. ?) I think I should take the pump apart and clean any casting crap out of it with a stone or dremel? and install the black spring? never opened an oil pump anything I should watch for? TIA, rick
 
#2 ·
I just check for any sharp edge and deburr with a 3M pad or 320 grit paper. Check so the pressure relief valve moves freely, take out the plunger and clean it. Use the high pressure spring.
Check end play, clean it and fill it with some oil.
 
#7 ·
The spring is what controls the pressure. Just about any pump will make pressure with enough spring in it. A HV just gets there earlier. It helps low speed pressures and with looser clearances. A regular one will do fine.....but all the hype about a HV being an issue is just that.

You don't want to run around at low speeds in bypass mode all the time..it should climb as RPM climbs. If it's near pegged at idle and maxes at low RPM a smaller pump will help....but that's usually not an issue with most BBC that are built without super tight clearances.


JIM
 
#8 ·
So Jim are you saying to leave the black high pres. spring out of the M77 and just use the spring that came installed? it's a freshly pro built engine but I don't know what the clearances are, I have an M77 HV SP pump in my 454 with 22,4xx mi. and it idles 30 psi and about 60 cruising so I originally thought the same pump for this engine would be a good choice but reading threads it seems like the M77 with a higher pres. spring is the way to go??
 
#9 ·
it's a freshly pro built engine

If that is the case why are you even messing with it ? Is there a problem ?? At some point in time you have to trust the guy that built the engine for you.
 
#11 ·
Hi Bill, the builder did the machining, align hone mains & cylinders and assembled the Mike Lewis rotating assembly then I did the rest

I still dont understand why you are changing the pump ?
 
#13 ·
I dont know how you can "think" that without knowing exactly what the clearances etc are in the engine.


I know most guys don't seem to be fans of HV pumps but one thing I have learned over the last bunch of years working on Mercruiser marine big blocks is that almost every one of them has a M77HV pump in it and they run just fine that way. Every one I have freshened up or done from scratch gets that pump.



Without knowing exactly what your pro builder did I guess I just dont understand why you would second guess him unless you were actually having a problem.


Just my opinion,
 
#14 ·
Bill I put the HV pump in without asking him what I should use, dumb on my part, I did ask a couple weeks ago and he said "Well if you're the kind of guy that likes to see a lot of pres. on the gauge it's fine" but then after reading a good amount of threads it seems like everyone uses the regular pump with a higher pres. spring ??? so I bought the M77 that came with the black spring, 2 actually, the M77HV is bolted to the engine now but the pan isn't on, I really don't want any problems with too much pres. if that's even possible ?
 
#15 ·
Bill I put the HV pump in without asking him what I should use

Ok, I thought he had installed that pump. Can he not tell you what the clearances are in the engine ? Tough call without knowing.



Unless they have changed something the M77 I have on the shelf comes with an extra blue spring for Corvette applications. I am pretty sure the blue spring is the higher pressure one ? It definitely is in the pump I have. Its been sitting there for a while so they may very well have changed the color of the springs.
 
#17 ·
I too have seen some of the the discussions suggesting the HV pump is "too much pump" in many cases. This after years and years of "hearing" that the HV pump was the way to go for "high performance" use. Is there a selection chart based on clearances or some other way that Melling provides to help choose which pump? Guess I will check their website.
 
#18 ·
From the "bible" how to Hot Rod BBC, the oem oiling system is perfectly mint. So I would go ahead with the swap to the non HV pump.

I ALWAYS take a pump apart, as I was taught, to check the castings for good machining, sometimes ball mill some channels, and then ALWAYS check end play, which is easy to check and reset even for guys like us at home. ( I wont ball mill any channels on my own at home - that was at a shop as an apprentice) THis is important especially for a USED pump. End play affect pressure/volume flow.

SO pull it apart, get your feeler guages ready and make sure its 100%!

PS if you're going to tack the inlet onto the pump DO NOT CHANGE SPRING until after, risk of heat treeating the spring.

PS, I 'm quite certain MJ used a higher pressure spring in my new engine, as I did in the 427. Both come up to 50+psi cold start. But seem rather normal at hot idle afterwards. 35-ish. One SFT one HR, And a little + psi while stealing a pony or two, aint a bad thing for either's longevity.
 
#22 ·
I called the shop today but got no answer ( its normal busy guy) so Im going to open up the M77 clean and smooth it, put the black spring in and put the new M77HV in the temp want adds here on TC for a discount price, put the pan back on, adj the lifters, put the manifold on and get ready to dyno 👍👍😀
 
#24 ·
Last time I dicked with an M77, I wasn't impressed with the oil path out of the pump. I sunk a 1/2" drill bit through the outlet to open it up. (Rough-cast, slightly smaller than 1/2")

This was several years ago, but this was the "new" style M77, metric bolts and (I think) powdered-metal pump gears.
 
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#25 ·
The Pink spring is the high pressure one- 70+ Psi
The Black one is about 60 psi
Purple is about 52 psi


A stock pump with a high pressure spring will work fine usually unless clearances are loose. Will still work, you'll just have lower oil pressure at low speeds.


My engine has clearances of .003"+ on rods and mains and solid rollers with pressurized oiling. I'm also feeding two turbos. I use a HV pump and actually have a couple of shims behind the spring to make a little extra pressure. Might give up a little power but I like it. Idle pressure is around 25-30 psi....8000 RPM is right around 80 or so.


I always remove the cover and sand the housing down to achieve .0005-.001" end clearance.



JIM
 
#27 ·
60lb is blue :)
List of Melling springs
 

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#28 ·
If you pull the pink/purple spring out of the M-77 HV pump and put into the std 77 you'll have a std volume HP pump. This spring is the 70# piece.

We've been selling those purple springs for years, we buy them a hundred at a clip (photo below)!

Thanks, Gary in N.Y.

P.S. Long before my good friend George (Richmond) retired from Melling we tried hard to have them offer this combo as an "M-77A" pump ready to go. They opted to offer up an asst'd spring package instead?
 

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#29 ·
So take the spring out of the M77HV pump and put it in the M77 and I'll have a better pump for this fresh 489 ? its a hyd roller cam with a roll master torrington bearing timing set , everything is new except block and its been torque plate and align honed
 
#30 · (Edited)
Hi y'all,

This is all good stuff. Discussions of oil pump, HV or std etc. I also have the full
performance library from the Chevrolet Power 3rd ed. thru Chevrolet Performance 2013
and most of the after market books on the subject, etc. From Gene's posts #18, #26
all the literature says GM stock oiling system is rock solid.

Here is what the authors have to say:
"Lubrication, the stock system works for you if you leave it alone."
They continue, "Chevy's stock oiling system is darned near
impossible to improve upon. Leave it stock and take advantage
of the enormous investment in development that GM put into
it in the first place." (ibid.)

Regardless, the follow on in pages show the L-88 pump and gears,
along with the Melling Hi Volume pump and how to modify them.

However, one thing rarely mentioned or seldom discussed is changing
the opening point of the blocks oil bypass valve. Going to a higher
flow/higher velocity pump also requires delaying the operation of
the bypass valve to ensure the engine has a clean supply of filtered
oil and not most of the oil not going through the filter.

Some where, not sure where there was discussed adding an additional
spring or washer inside the bypass ensuring oil flows through the filter
and not bypassing it, except in and emergency clog situation.
At least something to consider.

Good luck with your configuration,
God Speed!

PS - My three BBC all have the Melling HV oil pumps, I'm including the above for reference
if anyone cares to read it.




Fisher, B. Waar, B. (1971) How to HOTROD Big-Block Chevys. Chapter 13, Lubrication, p111.
Published by HPBooks, a division of Price Stern Sloan, Inc. Los Angeles, California. U.S.A.
 
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