I see that the one you tested was a Centuri one from 1973.

That may have been one that was actually manufactured at Centuri. I don't know when they shut down their machines (which had only been running two or three years), but I bet they didn't want to do the post-process drilling that Estes did, and that's what led to the development of the deep-pintle motors that Estes eventually adopted.

By the way. I haven't completely confirmed this, but I think you can usually tell Centuri manufactured motors by their labels. they had crisp printing and the motor designation was in reverse on a dark band. On later Estes manufactured Centuri motors, the motor designation band was just normal printing within a couple of borders, and the general look of the printing was a bit smudgier (is that a word?). The problem I still have with this is that the mini motors were printed the second way, and they were definitely not made on Estes machines (they had the longer casings and the partial graphite clay).

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Roy
nar12605