jimbote
Certified Volkswagen Nut
IIRC back when I did my BSM delete the chips were def of a cast iron nature...at least it drilled like other castings....I thought you meant an ES2 Norton thumper. you might have used a flat ended tap instead of the standard, although it might be hard to find, or break a tap in the middle and remove the taper, so not having to drill as deep. I would imagine the block is cast steel rather than cast iron, as you would have been able to tell the difference when you were drilling it by the chips.
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