Hi Basil I'm building the Sealion and in ETW's writings he stated case hardening the cam and that if you were worried about distortion get it hard chrome plated. I was like you very weary of the distortion so I looked at hard chrome plating but you get a change in dimensions as you are adding material.
I took my cam to a specialist hardening company to get their views on it and they agreed that distortion was a possible outcome. But the good news was they did Tufftriding which was stated by them to be a better alternative to hard chrome plating and because it is done in a salt bath at around 650c as opposed to case hardening at around 950c the risk of distortion was a lot lower and no change in dimensions.
So that's the way I went and the cam slid straight in the bearings and rotated just the same prior to being treated'
The rockers I case hardened
Paul
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