Received a bunch of NOS crankpin nuts. Fair amount of dirt accumulated in the thread as of a result of the location where found. Wanted to confirm the type of thread that these are most likely to be...BW, BSF or else. They are 3/4 x 19 ID. About to order tap and die to get them cleaned out. Anything else I should look out for, some taps seem to have a different thread vs what was made back then.

Thanks for your comments.

I had ordered these from Less, but for some reason no action there. So had to go to the other corners of the earth.

email (option): unpob@yahoo.com

Why don't you just soak them in paraffin and bead blast them, or just clean them with a wire brush on a bench grinder the wire brush would just about get into the thread.
I have a few good used ones if you asked!

email (option): davmax@ntlworld.com

Hi Henri...I think you will find the thread is a BSC (British Standard Cycle) thread...60 degree included angle, 3/4"o.d.x 20tpi. The 20tpi as opposed to the generally used 26tpi form was used on some larger sizes...Ian

Just a thought Henri...if you have a scrap crankpin you could grind a couple of slots along the threaded part with a small disc cutter and turn it into a tap..a bit crude but it would probably do to clean out the nut threads...Ian

Thanks Dave for that suggestion, already did it and scraped the inside of the threads on the nuts, but no dice. Even ran the crankpin on the wire brush, my number one tool. Hate to work with the bead blaster, stuff goes all over and makes the floor really slippery.

email (option): unpob@yahoo.com

Thanks for the info on the BSC Ian, will see first if I can obtain the tap and die. I think some of the threads on the crankpins were squished, in English, compressed...and the die combo might be best.

email (option): unpob@yahoo.com