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Kinda of recommended by forum discussion and most red blooded Americans:0.05mm/0.002" intake0.10mm/0.004 exhaust
I don't know where you heard that, but it's way too tight. Most people use .006 and .008 on that engine, AFAIK.
My US-spec Vintage manual recommends the tighter clearance. I expect it had more to do with passing emissions, but it also keeps the valve noise down. That said; I find that the 2valve Big Block runs a little better with the looser, �world� settings.
.004.006