how about some part numbers

 

GM white oil pump spring 3848911

GM oil pump screen 12550042

GM oil pump 12555283

Melling Oil pump shaft w/metal collar IS-55E (was in stock at local AutoZone )

 

I originally had a Melling M55 Standard Volume Pump installed and it made great pressure. The only problem was I dropped was dropping oil pressure over 4000 rpm (stock pan).

To fix my problem I ended up getting the same GM pump, spring and pickup as Shoebox and had it blueprinted by my machinist.

It turned out that my pressure problems resulted from the pump pickup being mounted 1.1" off the bottom of the pan (should be .250"-.375").

I decided to be conservative and install the new blueprinted GM pump. I discovered that my machinist had welded the pickup on this pump .830" off the bottom of the pan. Well I got he pickup height set correctly to .320" before installation and have not had any trouble since.

I can give you a smoken deal on a M55 pump but I would recommend going with the GM Parts and having a good machinist blueprint it.

My Melling pump made about 10 psi more than my stock pump but I am still making about 65-70 psi at 6000 rpm. Which ever pump you decide to install, make sure your pickup height is set correctly and have it tack welded in place once it is set.

 

I've been doing some searches on this site and others and apparently a lot of people have had problems with the canton oil pan leaking so I would say go all stock.

 

can most machine shops blueprint the pump and what does that cost?

 

Depends on how much work it needs. Mine cost $70 to have blueprinted but my machinist said that the passages all needed to be cleaned up and the two halves of the pum,p case did not fit together well and needed to be machined flat to each other. Anyway he indicated that it took more than he expected or it would have been cheeper. I would think $70 max.

 

So if you buy a new GM pump then it doesn't really need to be blueprinted right?

So what do you guys think of just using the Melling standard pump?

I've heard so many problems with the Canton Pans. Is there another brand that fits and doesn't leak?

 

so if u get the melling pump, its a good idea to get it blueprinted and if u get the GM one then u are fine?
Which one should i get?

I can get the melling one for 24 bucks, and the GM for 60.

Also should i use the stock pick up or aftermarket?
Thanks
Marcin

 

If your using the stock oil pan,,,,use the stock pump and pickup.

 

As far as 'blueprinting' an oil pump is concerned, it is made out to be more than it really is. However, if anyone wants to label the following steps blueprinting, more powa to ya.

ANY pump assembly, regardless of origin or amount of previous use, should have the gear to cover end clearance checked and corrected to .0020"-.0025". Obviously, if a used pump, check for, and correct any gear scoring/wear on cover.

I do not recommend welding pickup tube to cover. I prefer to (and recommend) welding a small brkt. to tube, and bolting it, to the cover. Exposing cover to unnecessary heat and stress is unjustified, AFAIC. One of those 'monkey see, monkey do' exercises.

Start with a performance pressure relief spring (if available), and from there, shim as necessary, regardless of pump used.

It is a good idea, so consider opening up [pressure regulating valve bypass passage]. Huh? This passage dumps excess oil volume the engine is unable to use, especially, when engine/oil is cold. This oil gets 'dumped' into the area of the pump, that receives incoming oil. If not controlled, this dumped oil can disturb incoming oil supplied to pump.

On the subject of HV pumps, I pose this ?. What was used on 350s reving 8000 grand, in the pre LT1 days? I'll give ya one guess. BTW, they didn't need the larger dia. pickup tube (as LTx engines use) either. You maintain 65-70 psi at high revs, you'll have plenty of volume. This HV craze, to me anyway, is another example of the above, 'monkey see monkey do'. Someone in racing competition (for a specific need or requirement) has/uses one, so I need one too, syndrone. whatever turns your crank, I 'spose.

Also, FWIW, I find aftermarket pump gears to be machined with a bit more precision. By that, I mean you end up with a 'tighter' gear to gear clearance, which by itself, will generate more pressure. I know I've touched on most of this, here, in the past somewhere.

 

OK..HERE IS WHAT I AM GOING TO DO....Good or bad?


Stock melling M155 with the white spring?


Thanks
Marcin

 

Used a melling hv oil pump. All good here.

 

 

I swear by a bone stock GM pump.. No need for a high volume pump.. One car I worked on had almost 600rwhp on a stock pump..I personally know other guys using a stock pump at even higher h.p. levels..

Even Lingenfelter uses stocker pumps..Just make sure it is the pump with the larger diameter pickup. There were 2 different types used in these cars until 1996 when the larger pickup was standard.

 

New pump is always good . Stock or H V ..