I am running a mix of Goopy 12.5mm studs with stock size studs. I drilled the motor with a 33/64 bit. All studs would slide in place and start to thread fine. However as I threaded all the way I would get resistance and noticed the stock dowels pins were then stuck, binded by the twist from lack of clearance. I dont feel this is good and have not assembled my motor because of this, instead I have spent days and days using sanding bits in the areas that show signs of touching. I will never attempt to drill a motor again but send out to a cnc shop.

So what are your thoughts for those that have studed there own motors?

I really want to make sure I do this correctly since this will be on a 800hp+ semi perpheral motor.