Core Plug Sizes and Material

[Robert Leigh]

I would think stainless stel core plugs would be very satisfactory. I imaging that mild steel have normally been used for cheapness. I suspect that modern ones are thinner than the originals because they seem to fail more quickly. I always use stainless studs for securing water joints to the block and head, with stainless or brass dome nuts and fibre washers. This prevents water leakage up threads.