C2 oil loss

[Duke W.]

Hydraulics 101

The oil pump is a CONSTANT VOLUME design. It delivers volume approximately proportional to the speed it is driven. Double the speed and the pump delivers double the volume.

Because the pump is pumping into a hydraulic resistance, pressure increases as pump speed/delivery increases. Once pressure reaches the point where the bypass valve opens, excessw volume is shorted back into the pump inlet. The "normal" pressure relief spring on hydraulic lifter SBs and mechanical lifter SBs up to late '63 should yield 40-45 psi at 2000 engine RPM with fully warmed up oil.

If the pressure doesn't exceed 30 psi at high speed then then there is either a problem with the spring, the pump, or a major internal oil leak.

The standard pump has PLENTY of capacity to deliver the 55-60 psi with the stiffer spring that was used on late '63 to '65 mechanical lifter small blocks.

Duke

[Scott S.]

Re: Hydraulics 101

With Melling pumps, don't they now make 2 different M55 styles? One with "standard" casting, & one with "hi perf" casting? One is supposed to be for mild/stock engines & one for stock Hi perf engines. Is this correct?

[Scott S.]

Re: Hydraulics 101

With Melling pumps, don't they now make 2 different M55 styles? One with "standard" casting, & one with "hi perf" casting? One is supposed to be for mild/stock engines & one for stock Hi perf engines. Is this correct?

[Duke W.]

Re: Hydraulics 101

They offer two basic Gen I small block pumps - "standard volume" and "high volume". The high volume pump has either larger diameter or longer gears. That's the only way to get "more volume" from a constant volume design, but it's NOT NECESSARY for any road engine including OE SHP engines.

For a road engine, even one that will see occasional racing, you ONLY NEED THE STANDARD VOLUME PUMP! Pick the "low pressure" version if you have a SB with a 60 psi gage, and the "high pressure version" if you have a SB with an 80 psi gage.

The high volume pump is ONLY NECESSARY if you have a loose clearance REAL racing engine, and you actually race.

You can buy the correct OE replacement pump from NAPA (Clevite brand) or any parts store that carries the Federal Mogul product line. (Seal Power brand).

There is nothing special about Melling brand oil pumps. They, along with the rest of the hot rod parts industry, want you to think there is, and they have brain washed the masses with advertising for 30 years, but their product is no better or no worse that the OE replacement brands.

My '63 340 HP engine endured some tough use in its first life of 115K miles, which included at least 1000 miles of hot lapping race tracks. When I took it apart the bearings looked virtually new - all with the standard volume, standard pressure (40-45 psi) oil pump - the same one they used 2-bbl. 283s.

Duke

[Duke W.]

Re: Hydraulics 101

They offer two basic Gen I small block pumps - "standard volume" and "high volume". The high volume pump has either larger diameter or longer gears. That's the only way to get "more volume" from a constant volume design, but it's NOT NECESSARY for any road engine including OE SHP engines.

For a road engine, even one that will see occasional racing, you ONLY NEED THE STANDARD VOLUME PUMP! Pick the "low pressure" version if you have a SB with a 60 psi gage, and the "high pressure version" if you have a SB with an 80 psi gage.

The high volume pump is ONLY NECESSARY if you have a loose clearance REAL racing engine, and you actually race.

You can buy the correct OE replacement pump from NAPA (Clevite brand) or any parts store that carries the Federal Mogul product line. (Seal Power brand).

There is nothing special about Melling brand oil pumps. They, along with the rest of the hot rod parts industry, want you to think there is, and they have brain washed the masses with advertising for 30 years, but their product is no better or no worse that the OE replacement brands.

My '63 340 HP engine endured some tough use in its first life of 115K miles, which included at least 1000 miles of hot lapping race tracks. When I took it apart the bearings looked virtually new - all with the standard volume, standard pressure (40-45 psi) oil pump - the same one they used 2-bbl. 283s.

Duke