I used to make the kits for the Speedmaster heads until bad things started to happen, and ONLY on the Speedmaster heads. I'm sure I did yours prior to that knowledge and experience. Keep an eye on the bolts that they are staying tight.
I have a brand-new set in the shop that looked like they had been corrected by Speedmaster when I took them out of the box, but after a closer look, they were incorrectly machined as well. Maybe @SSG Karg can chime in. He saw them firsthand. I think they came from the 2020 Black Friday sale, so they hadn't corrected them by that point, and I doubt they have yet.
These are just a few of the pics I have of damage caused by this issue. The end results of the bolts or studs working loose.
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