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Topic Review (Newest First)
09-26-2012 04:02 PM
jeepers creepers Good news,
i put on a new pump (M55 Stock ) and TIG welded a bracket attached to one of the pump cover bolt, oil pressure is pretty good and it doesn't drop too much when hot, got solid 10 PSI at idle with 5w40 full sinthetic.
09-14-2012 07:00 AM
Irelands child Take a wander on the internet - M-55 Melling pumps have been a problem for a while. Yours might not be in that bad batch, but ....... oil pumps are too cheap to worry about a potential problem. A caveat, if you end up with a different brand - unfortunately, that too might just be a repackaged Melling as well but it will probably have the Melling number on it.
09-14-2012 06:21 AM
cdminter59
Oil pump and pickup

Why don't you just purchase a pump like this, with the pickup already welded. Moroso 22124 - Moroso Oil Pump and Pickup Kits - Overview - SummitRacing.com.
09-14-2012 03:46 AM
jeepers creepers Bad news about thepump mods i did, oil pressure is too low wen engine is hot it drops to zero, i'm gonna put a new stock one and see what happens, i'd like to fabricate a bracket for the pick up at this time instead to braze that, brazng is probably better to avoid air be sucked but i guess i can use a sealant while sticking it in the pump.
03-19-2011 05:45 PM
jeepers creepers
Quote:
Originally Posted by lmsport
The difference in spring tension between the M55 and the M55A is not great, but the oil pressure goes up about 15psi. I think you will see more than that. I have put the pan on with a couple bolts and some oil and run the pump with priming tool just to see what the pressure is doing. I expect to see about 70psi on a cold engine with the priming tool and Mobil 1 10-30. As long as you have made a oil groove on the distributor body to spray on the gear mesh location, I think you will be OK.
i'm concerned...
Reading the article of the relief spring, they say that drilling a larger hole by pass passage way is needed to ensure an adequate oil bypass during cold starts and high rev pressure conditions, so can you explain better how does this work because i believe i'm missing something...
03-19-2011 05:13 PM
lmsport
Quote:
Originally Posted by jeepers creepers
Yes, i'll check for flatness and correct clearance after brazing the pick up.
About the relief spring, do you know how much pressure will increase before the piston will be open? i know it sound pretty silly but i'm obsessed about the load on distributor and cam gear, i guess nothing noticeable, can you confirm this?
The difference in spring tension between the M55 and the M55A is not great, but the oil pressure goes up about 15psi. I think you will see more than that. I have put the pan on with a couple bolts and some oil and run the pump with priming tool just to see what the pressure is doing. I expect to see about 70psi on a cold engine with the priming tool and Mobil 1 10-30. As long as you have made a oil groove on the distributor body to spray on the gear mesh location, I think you will be OK.
03-19-2011 05:01 PM
jeepers creepers
Quote:
Originally Posted by ChevelleSS_LS6
I had a sudden drop of oil pressure, to zero. I was running a Fram. Never again! Being that some Wix (or Napa brand, same thing) filters are made in China, I've moved onto Baldwin or Hastings filters. Even purolator is a good step up in quality from fram (compare the two at your local auto part store). I made the choice to spend 5 bucks on an oil filter, it's cheap insurance for a $3500 engine.
i've heard bad things about Fram filters, here in Italy they're common and easy to find, NAPA unfortunately doesn't exist and other brands like Purolator or Wix are hard to find at local autostore, what about Fleetguard? because i can get them.
03-19-2011 04:40 PM
ChevelleSS_LS6
Quote:
Originally Posted by cobalt327
Use a good oil filter, too. The Fram filters have been reported to have problems associated w/pressure loss.

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I had a sudden drop of oil pressure, to zero. I was running a Fram. Never again! Being that some Wix (or Napa brand, same thing) filters are made in China, I've moved onto Baldwin or Hastings filters. Even purolator is a good step up in quality from fram (compare the two at your local auto part store). I made the choice to spend 5 bucks on an oil filter, it's cheap insurance for a $3500 engine.
03-19-2011 04:32 PM
jeepers creepers
Quote:
Originally Posted by lmsport
FWIW, the plug will change the static spring tension resulting in a higher pressure to open the regulator. Make sure the cover and body are still flat. I use some 300 grit paper on a mill table or a piece of glass to make sure the covers are flat. The end clearance on the pump gears should be no more than .002".
Yes, i'll check for flatness and correct clearance after brazing the pick up.
About the relief spring, do you know how much pressure will increase before the piston will be open? i know it sound pretty silly but i'm obsessed about the load on distributor and cam gear, i guess nothing noticeable, can you confirm this?
03-19-2011 04:15 PM
V8&4spd The HV pump will fit into a stock oil pan. From what I can see the HV oil pump pick up will be deeper into the oil pan.
03-19-2011 03:41 PM
lmsport FWIW, the plug will change the static spring tension resulting in a higher pressure to open the regulator. Make sure the cover and body are still flat. I use some 300 grit paper on a mill table or a piece of glass to make sure the covers are flat. The end clearance on the pump gears should be no more than .002".
03-19-2011 02:16 PM
jeepers creepers Did some work today, as i said before there was a new oil pump and pick up as well on the shelf so i've decide to make the mods to get a better hydrostatic balance and keep the stock one wich is in the engine right now.
The grinder i've used is great but the bits not that much so the grooves aren't perfect for sure , i just hope they work.
I've grinded also the casting flashes ,wich on the pick up inlet were very bad, i believe the flow should be better now.
The roll pin has been replaced by a threaded plug and the bypass hole enlarged and the tiny plug replaced with a bigger one (1/4" NPT), unfortunately the wall was thin so i had to braze it up .


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03-19-2011 11:36 AM
spinn
Quote:
Originally Posted by MouseFink
As I mentioned before, stock volume oil pan should never be used for racing even though some claim to be able to get away with it.

Who told you this . A stock 5-6 quart pan is fine. Tack your pickup that way it is full suction. The pump is a personal matter.
03-19-2011 11:31 AM
MouseFink
pan volume

I never said a HV pump can "suck a pan dry" although it is possible.

The theory is that at a sustained engine speed above 4500 RPM, the engine has about 3-1/2 quarts flowing through it. If your oil pan only has 4-1/2 quarts to begin with, the remaining quart of oil in the oil pan becomes critical, especially with solid lifters and no oil restrictors in the lifter bores. The stock oil pans are limited to 4-1/2 to 5 quarts of oil because it is difficult for the factory to design a high volume oil pan for a street driven passenger car. That is one reason the factory did not equip high performance cars with HV oil pumps. The GM Corporate Office insisted that all high performance cars had to be driven on the street. The exception was the 409 Chevrolet and the 421 Super Duty Pontiacs which were equipped with a modified stock pan that was welded and extended deeper for 8 quart capacity. Notice how high the front end is on those cars? That is partially for oil pan clearance. This is not a problem unique to Pontiac engines. As far back as 1965, Chevrolet used "edge oriface" lifters with their famous 30-30 fuel injection cams. Those lifters had the oil feed hole on the body of the lifter rather than in the oil groove. I used those lifters in my '56 and '59 Chevys in 1966 through 1969. I have even heard that before 1965, drag racers put pipe cleaners in the pushrods to restrict oil flow to the rocker area. That was before roller rocker arms were introduced an many engines that were so equipped burned up the rocker balls.

I have proven that a HV pump can suck a pany nearly dry with my '69 Firebird 400 street/race car. I was using a Melling high pressure 455 SD oil pump and about 6000 RPM, the solid flat tappet lifters were rattling downb the return road. That was because the stock 4-1/2 quart oil pan was nearly empty at 6000 RPM and the acceleration was pushing the remaing quart of oil in the pan up the back of the oil pan and away from the pick up. When the engine idled for a minute, the oil pan began to refill and the lifter noise went away. I spun out rod bearings on two occasions before I decided to install an aftermarket 7 quart oil pan. I finally switched to a hydraulic flat tappet cam and used Melling JB-951R limited travel (RA-IV) hydraulic lifters. I had no more problems oiling after that. The Crane hydraulic lifter cam and Melling JB-951R limited travel hydraulic lifters were good to 6300 RPM, just like the previous solid lifter cam. I also quit driving the Firebird 400 like it was a 327 Chevy.

Unfortuantely, driving the Firebird like it was a Chevy was the only way I could beat a Chevy.
03-19-2011 09:49 AM
cobalt327
Quote:
Originally Posted by MouseFink
...a Melling +25% higher volume Melling Select oil pump should never be used with a stock volume oil pan. The Melling (+25%) HV oil pumps are considered racing oil pumps for engines with wider bearing clearances.
Why? Please tell me it's because "it'll suck the pan dry!"
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