Exactly, time and set-up, are what's costly.
Tom, you are the first I've seen even mention expansion rates, so I know you must have a handle on it. Those were lessons hard learned by a lot of us older guys when doing BBK kits on VW's back in the 60's & 70's. The amount of magnesium in their aluminum alloy was wild, with expansion rates, specially on racing(drag) engines. Where a full warm up temp and beyond, often wasn't seen until the engine shut down, and started equalizing. It was about then, we found heli-coils to be our best freind on the cylinder studs, as they gave a wider footprint in the soft alloy cases, and acted as a heat sink medium, or step between the alloy, and plain steel VW stud. They work quite well on GY6's too, same reason.
Later man, I'm sure anyone needing your services will get excellent work, done by a knowledgeable Mechanic.
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kliff
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