Bonjour,
I could make some progress in disassembling by engine. I’m now at the level of the oil pump. Installed is the “Melling high volume oil pump M84AHV”. What are your experiences with that pump?

Brgds

Hartwig
Original Post
My experience is to go with a stock volume oil pump because I was told by a Pantera mechanic that the high volume pump will put too much strain on the distributor drive gear and that oil pressure is over rated. I am not saying this is necessarily the best advise just my experience. Good luck!
The only reason to go with a high volume Oil Pump is if your engine is SEVERELY WORN. As mentioned it puts unessecary stress on your Distributor and Cam Gears. If you can maintain 10Psi pr 1000rpm it is sufficient. Best use a standard pump but blueprint it i.e. check that all tolerances meets Ford's specifications (I will find them for you) and use a 5w-30 or 10w-40 Synthetic Oil for best flow and optimum lubrication. Flow keeps your Bearings alive.

A rebuild Engine will have no problem keeping Oil pressure at 70Psi from below 3000rpm warm with 5w-30 Synthetic Oil with a standard Pump that is verified for correct tolerances. Btw even a new Pump should be taken apart and checked before installed.
Ford Oil Pump Specifications:

Rotor endplay 0,001-0,004 Inch
Radial Clearance 0,006-0,013 Inch
Shaft to Housing Bore Clearance 0,0015-0,0029 Inch
The stock OEM 351C oil pump has higher volume than the oil pumps of other Ford engines. So the Melling "high volume" oil pump is actually "extra-high-volume". The standard pump should be enough. A high volume pump will only serve to pump oil in the wrong direction, such as the valve train and the cylinder walls, unless steps are taken to prevent this.

You may ask why is a double high volume oil pump even sold? Because the 351C lubrication system is problematic. The Ford specification is 60 psi hot oil pressure, from 2000 rpm and above, +/- 10 psi. If your engine cannot maintain at least 50 psi "hot oil pressure" from 2000 rpm and above, it is because the "leaks & clearances" in the engine are over-taxing the capacity of the standard oil pump ... which was already a high volume pump ... this cannot be argued.

I have found installing a high volume oil pump simply creates a possibility for additional oil burning by throwing additional oil on the cylinder walls. If a person is going to install a "high volume" oil pump in a 351C, they must take steps to control where the oil is flowing, otherwise there is no guarantee that the additional oil is helping anything. Without taking any additional steps to control the oil the additional oil supplied by the high volume oil pump shall flow to same place that the wasted oil is already flowing. BUT, if you take steps to control where the oil is flowing, the engine may not need a high volume oil pump at all. The high volume oil pump issue is like a dog chasing its own tail.

Ford installed a "high volume" oil pump in this engine as original equipment because it had a lubrication problem. It couldn't make enough hot oil pressure. I have written over and over and over about the subject. What the engine really needs is tappet bore bushings. The bushings resolve the problem properly. With the bushings the standard pump supplies more than enough oil. The hot oil pressure shall be at the top-end of the specification (70 psi). The rod bearings shall be supplied with enough lubrication.

351C lubrication

There is an easy way to fix this, it cost $400 USD.
Last edited by George P

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