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Mmm. I question the assumptions made here. Firstly that the alloy head will be at or near the stud temperature. The welder current flows through the stud and block – how rapidly does it reach bright red? What transfer of heat takes place, in the time available, into the head which is itself a large heat source and a good conducter? So is it correct to just look at the differential expansion rates – if that were true then the head and its corrosion products would expand away from the stud without any pressure and close back onto it with cooling.
Secondly, is it reasonable to imply that Doug Kephart’s detailed report amounts to just a doubtful claim? He did do it and unscrewed all the studs. If not then what would have been the the point of his articles?
And rather little preparation in fact. No soaking in diesel for months for a start.
Cutting through the studs as recommended aint so simple either. If a milling cutter does the job for the peripheral studs what about the inner ones? A band saw runs the risk of damage. And you also end up having to get the studs out, by drilling and tapping presumably.
Doug Kephart’s engineering knowledge and experience is second to none, as any reading of his many articles about his Douglas and Scott bikes would confirm. He got a bit of similar stick from doubters before when he first published his rebuilding – a – Brum series in Yowl. Nobody said they had tried the welder trick and found it didn’t work.