Sometimes when a new "better idea" comes along, it takes a while before we find out why it wasn't common practice all these years.
Many of you may remember previous discussions of dressing ball-check seats, and the burnisher approach. I have been evolving my sump ball-check burnishers in several ways, and even attempted to avoid compromise to the point of subbing out some of it to real live machinists and welders. Yet now, after tooling up to assure low cost as well as quality control by doing it all in-house, I find that the seats are not always concentric to the pump's threads.
No wonder my sloppy prototypes produced the best results.
Although I do not solicit folks to send me pumps, one presumed WLA body has presented genuine concerns with dressing techniques. The casting was phenomenally hard; It cut more like "chilled" cast iron than steel... and believe me "cutting" was a last resort. Even stroking the gasket surface upon a stone made it "sing".
The pump arrived filthy, semi-polished and half-primered, and the bypass frosted in securely.
Upon cleaning, arthroscopic inspection revealed enormous pitting in the primary sump ball-check.
My diamond-dressed piloted stone quickly displayed the concentricity problem.
It was actually worse than the general pitting, but for one enormous crater right on the seat.
With nothing to lose, I spent time on fashioning a 29/64" counterboring endmill from drillrod to take the seat surface down from the top to produce a flat surface, and sharp edge to the gallery below for a place to dress the new seat. At this point it became apparent that the gallery bore was several thou off center from my pilots.
Whether this is a WW2 fluke, or other models and vintages of H-Ds share problems, or even if some occasionally have been in a fire and then buried in mud before cleaned up for ebay,.... The application of burnishers has its cautions: For as I attempted a go at it anyway, not only did the hard casting mar the burnisher badly,... it chipped the casting instead of forming it!
Ultimately the seat was refinished at the expense of another stone and burnisher, and some finesse, but lowered .060" in the process.
After having applied my burnishers to a few dozen OHV pumps, a few 45" motors on the bench a decade ago, and a pre-'41/post-'51 pump or two in my reference drawers, slight marring of the burnisher's ball required many uses, as the castings have been malleable.
Destroying one in a single use is an extreme example, but now calls for serious reconsideration.