Thanks, John! I really appreciate this kind of information.I don't think it was the best idea to media blast the internal surfaces of the pump. That should be a machined surface for the rotors and not a rough surface like I see in the pics.
Somewhere, in the manufacturing drawings for those parts, there would have been a spec for surface finish and while I don't know what that is, I'll say that the media finished surfaces exceed that spec by a lot. I've had quite a few oil pumps apart over the years. The cover is usually a ground surface for example. When the surfaces get scored or otherwise worn, you start to lose pressure. IMHO, the rough surface will do the same.
You are spending a lot of time and money to get this car as perfect as you can. While the pump will probably work, I don't think it will work as well as it could or as long as it should.
Your car though... and your decision. I just know I wouldn't run it and I've built a few engines over the years.
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It didn't occur to me that the surface structure would be a problematic. I use glass beads as blast media, which doesn't remove metal from the blasted parts; it just mattify the surface.
However, if this is really a problem, I would rather buy a new pump.
Do you have any recommendations for buying a high-pressure or high-volume pump?
The machine shop enlarged these four oil passages, in case that information is relevant.















