[Skip Fix]

How many of you are plugging the oil bypass passage in the filter housing? What does that little spacer fitting for the oil pressure gauge really do besides space out the sender to turn it easier?


Oil pumps Sealed Power vs Mellings. well in looking over 4 pumps I have a few things noted. Two Sealed Powers one that is supposed to be a RA replacement(odd number but that's what Federal Mogul said looks like a typical Mellings/RA IV type) New Sealed Power that came with a rebuild kit(has a M54D tag on it!). An old Mellings M54d (thick plate) a new Mellings (stamped plate). The Sealed Powers both have the thick bottom plates that are completely flat. The old Mellings has the thick plate with a slot cast in it, corresponding to the slot in the stamped plate. I know the Moroso and other racing SBC and BBC pumps have a slot for each gear ground.

Both Sealed Powers have a smoother finish on the sides where the gears ride compared to the Mellings. The new Sealed Power does not have the distibutor drive shaft pressed almost to the bottom of the gear like the others. Both Mellings and RA Selaed Power have an "olive" spring. The new Sealed Power(or Mellings) has a dark green one, all have the extra spring to lower pressure.

Interesting differences and the Sealed Power with the same tag as a Mellings number.

So at idle is the ball seated? Isn't it just a high presuure bleed off and unseats at the high end? So every pump should read about the same at idll til it bypasses?

[Skip Fix]

How many of you are plugging the oil bypass passage in the filter housing? What does that little spacer fitting for the oil pressure gauge really do besides space out the sender to turn it easier?


Oil pumps Sealed Power vs Mellings. well in looking over 4 pumps I have a few things noted. Two Sealed Powers one that is supposed to be a RA replacement(odd number but that's what Federal Mogul said looks like a typical Mellings/RA IV type) New Sealed Power that came with a rebuild kit(has a M54D tag on it!). An old Mellings M54d (thick plate) a new Mellings (stamped plate). The Sealed Powers both have the thick bottom plates that are completely flat. The old Mellings has the thick plate with a slot cast in it, corresponding to the slot in the stamped plate. I know the Moroso and other racing SBC and BBC pumps have a slot for each gear ground.

Both Sealed Powers have a smoother finish on the sides where the gears ride compared to the Mellings. The new Sealed Power does not have the distibutor drive shaft pressed almost to the bottom of the gear like the others. Both Mellings and RA Selaed Power have an "olive" spring. The new Sealed Power(or Mellings) has a dark green one, all have the extra spring to lower pressure.

Interesting differences and the Sealed Power with the same tag as a Mellings number.

So at idle is the ball seated? Isn't it just a high presuure bleed off and unseats at the high end? So every pump should read about the same at idll til it bypasses?

[Tom Vaught]

Quote:

"How many of you are plugging the oil bypass passage in the filter housing?"

I am, as I do not want unfiltered oil in my engine
it is only there for extremely dirty oil filter
by-pass issues. We change oil and filters enough
that it's purpose will never be required. It can
open on high pressure/acceleration modes.

Quote:

"What does that little spacer fitting for the oil pressure gauge really do besides space out the sender to turn it easier?"

About it.

Quote:

"Oil pumps Sealed Power vs Mellings. well in looking over 4 pumps I have a few things noted. Two Sealed Powers one that is supposed to be a RA replacement(odd number but that's what Federal Mogul said looks like a typical Mellings/RA IV type) New Sealed Power that came with a rebuild kit(has a M54D tag on it!)."

Should as Federal Mogal never built any oil pumps
They have always bought from Melling and repackaged.

Quote:

" An old Mellings M54d (thick plate) a new Mellings (stamped plate). The Sealed Powers both have the thick bottom plates that are completely flat. The old Mellings has the thick plate with a slot cast in it, corresponding to the slot in the stamped plate. I know the Moroso and other racing SBC and BBC pumps have a slot for each gear ground."

The old Mellings with the cast thick plates used
the oil slot to pressure balance the gears so that
the gears would not float back and forth between the pump body and the gear cover. The pressure
slot is used on many Gerotor type pumps too.

Quote:

"Both Sealed Powers have a smoother finish on the sides where the gears ride compared to the Mellings. The new Sealed Power does not have the distibutor drive shaft pressed almost to the bottom of the gear like the others."

Save 1/2 inch of steel on every pump and you save thousands of dollars.

Quote:

" Both Mellings and RA Selaed Power have an "olive" spring. The new Sealed Power(or Mellings) has a dark green one, all have the extra spring to lower pressure."

Most springs are color coded not for pressure but for spring vendor. Whether the spring is "Olive"
(light green) or dark green it will still be a
60 psi spring. The second spring in the boxes is
to lower the pressure to 40 psi.

Quote:

"Interesting differences and the Sealed Power with the same tag as a Mellings number."

Same pump, built to Federal Mogal/Sealed Power
specs.

Quote:

"So at idle is the ball seated?"

YES! Unless you have a high restriction after the pump like cold oil and/or a dirty filter

Quote:

"Isn't it just a high presuure bleed off and unseats at the high end?"

At some point the pump will overcome the restriction in the oil system and the by-pass will
open and maintain a certain flow of oil to the
system if the rpm of the engine/pump does not
change.

Quote:

"So every pump should read about the same at idll til it bypasses?"

Not true as even though the pumps will pump the same volume per engine revolution, restriction in
engines will vary due to bearing clearances and
lifter/ cam journal clearances therefore pressure will vary from engine to engine at idle.

Tom V.

[Skip Fix]

Thanks Tom. My 78 TA came stock with the softer spring(there are even specs in the shop manual for what pressure at what rpm) and I could remember watching the pressure drop when cruising when it hit that bypass pressure.

I meant same pressures at idle on the same motor(ie clearances, oils etc.). My current roller motor has alot looser clearances and alot less pressure at idle, maybe 20 when warm, compared to the normal 40 on my tigher clearance street motors.

The early Hilborn unit looks like it will work. All the bolt holes need redrilling even the two center ones. Throttle shafts a little rough so may need a freshening at Hilborn. One more project down the road! Since the stacks point at each other can fit longer ones for torque tuning.

[Skip Fix]

So which pumps do you use Mellings with a plate and the slot, Sealed Power flat thick bottom plate? Or make a groove in a Sealed Power bottom?

[tikiklubracing]

xtra spring is for 301 motor.

When usure ask. BIGGERISBETTER-78 Catalina 400 .060, 3.73 spool, :TH350. 15 yrs in NHRA tech ret. Check em out, www.nhra.com. or www.ihra.com or to find tracks www.chasinracin.com