High pressure vs. low pressure oil pump

[Duke W.]

Re: High pressure vs. low pressure oil pump

Nobody ever said that high volume, high pressure pumps are "detrimental" to small blocks - other than busting a PV if the usual 60 psi gage is pegged (and there are LOTS of complaints about this). However there is a downside despite no benefit.

They pump more oil than necessary on a normal clearanced road engine, most of which is shorted back into the pan, and this will cost power, fuel economy, and increase oil temperature.

So what is the justication for installing them in a restoration engine that will be used like typical vintage Corvettes, most of which will probably never be run as hard as they were in their first life?

Chevrolet didn't find it necessary for full engine life.

Why spend 50 bucks or whatever they cost when they aren't necessary and no more than an hour's worth of work is required to make the OE pump serviceable for the life of the rebuild.

It's like using premium fuel in a seventies vintage engine that was designed for and runs detonation-free on regular 87 PON fuel.

There is no benefit for the additional cost.

If you build hot rod motors and want to use a HV/HP pressure pump, that's your choice, but that doesn't mean that the typical vintage Corvette owner who wants to restore his engine to original specification and doesn't plan on racing it should use one.

Duke

[Thomas B.]

Re: High pressure vs. low pressure oil pump

Melling 10553 -
Check the spring. I bought this pump 2 weeks ago from a large reputable parts house. Web site clearly states "standard volume" and "standard pressure". Started engine, pegged the gage. Box and part clearly labeled 10553. Called parts house, and they tell me Melling now shipping these pumps with high pressure spring installed, and no other spring in the box. Not sure this is true but caveat emptor. Parts house is having Melling ship me a spring and he is sending me a new oil pan gasket and RTV, and promises to correct website. FWIW, avoid my mistake.

[Dan D.]

Re: High pressure vs. low pressure oil pump

Unreal. I bought my 10553 about a month ago - had medium spring installed, high pressure in the box. Melling sent me a 49psi - no charge.
What are they doing. What is driving this. As Duke and Tom Parsons point out, it probably will not hurt the engine, but there are drawbacks, and pegging the gauge on these older cars is not acceptable. -Dan-

[Domenic T.]

Re: High pressure vs. low pressure oil pump

I can't count the number of small blocks I rebuilt and NEVER did I have to but a new pump.

One reason is that when I took them apart I liked what I saw.

Another reason is that I've been given gobbs of good pumps from other guys that buy NEW pumps that really don't need one.

If I need one I have a selection of good pumps to choose from.

I might add that if you go WAY over board with preasure or your bypass valve sticks closed, you can liquid blast the babbit off your bearings.

Extreme case but true.

DOM