In reviewing the video for Saturdays test I realized I have a seal problem.
The first short test:Video
The second long test:Video
If you look at the very bottom end of the motor on the first run there is a minor leak/spray where the throat seals to the outer aluminum. On the second run this is a huge gushing torrent until the copper throat gets hot enough to seal. (You can also see where this leak seals up on the chamber pressure graph)
The seal is is a a 1/8" 0.139 nominal high temperature o-ring.
The mechanical details are shown below. The pressure is about 350 PSI not trivial, but not huge either.The clearance between the copper throat and aluminum outer closure in almost zero. The motor was assembled with a rubber hammer its very tight. Its quite clear that the seal failed after the first test. Any ideas on what is wrong?