Re: 74 Lotus w/ minor/micro cracks in piston sleev
Oddly, I have this in one of my own. Back when I first saw it, in '75, I was in abject panic. Thought of delaminating, overheat damage (tho I'd never boiled it), poor casting due to lower than necessary temps to keep iron from "folding" when cast... the engine had done 80K to that point, we were befuddled. We're talkin' metallurgists, N.D.T. Nuclear Grade Inspectors, MetalMites all, here. Concluded there was aught to do but have it bored +.010, inspect and reassembled it. Ran it for 11 more years, nearly 100K, and will repeat the process again. Still suspect "folding" as the answer. The "cracks" are quite "tight" here. Evident, but it doesn't ~seem~ to matter to the overall running. It may allow a somewhat premature ring wear but not that I've noticed with a relatively stock engine ("SE" cams).
I've been into many, MANY kent engines in my time and only now have I heard anyone else with this, almost forgotten it! I'll check engine number and report back. Mebbe there WAS a batch run at temp's too low for homogeneity. Fascinatin' ain't it?!