Oil pump questions

hotcoupe

hotcoupe

Well-known member
I have a 239 c.i.,full floating rods with 10 k onthe clock. Changed oil today, bearing material in the oil (small, thin flakes), so the motor is coming out. My question is, i have a new Melling M-19 pump, can i use this pump without any adverse effects? I didn't mention, the motor will be completely disassembled,cleaned,new bearings, crank polished or ground, big end on rods checked for round.
Thanx,
Tom
 
One more thing, why are there two oil pressure relief valves? One on the pump and one at the front of the engine in the valve chest.tom
 
The one in the block was the only one from start...the early pumps didn´t have a relief valve in them.
And you can´t take the relief valve in the block away or block it out even if newer pumps have a relief valve since it is lubricating the camdrive.
 
Flatheadmurre, thanx for that info, i was unaware that the early pumps didn't have a pressure relief. I guess i should have been more direct when i asked about the M-19 pump. So . . . Am i going to create a problem using an 80# pump in an application that calls for a 50# pump? Thanx in advance for your response.
Tom
 
The right place for the relief valve is at the end of the system, as in the early blocks. Not sure why Ford changed. Back in the 60's we were having bearin problems, so I added a gauge at the front of the oil manifold, bu drilling a small 1/8 hole in through the front of the block (8ba). THere was a 10/15 lb drop between the two gauges. After you take apart as many blocks as i have, you'll see the front bearings are warn more and fail sooner.
 
The pressure is set by the weakest relief valve in the system so your 80# pump will only reach 50# before the block relief valve opens.
The only thing the shortbody pump changes is that it has a higher displacement so you get some more flow.
 
Do not buy an after market pump from Speedway. I put one in a new build (8BA) and it produced marginal oil pressure. I replaced it with a known good used pump and the oil pressure came back to normal.
 
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