This is the E3238 7/16" x 20 tpi engine nut as fitted to many Norton engine bolts. It has the correct 'reduced head' and greater depth than other commercially available nuts of this thread/size - and is CNC made specially by us for fitting to Norton engine bolts, but in stainless steel.
Note: the thread for this nut is 7/16" x 20tpi UNF profile. This is almost identical to the original 7/16" x 20tpi BSC thread, but with a fractionally different tooth profile. I recommend if using these nuts with original bolts you buy one nut and try first. If bought with our corresponding bolts they are a matching pair. Unfortunately original BSC taps in this size are no longer available.