|They should all be the same OD regardless of type as per the standards, though cheese head and the button's allen key size is from experiance one size smaller which is a pain. I'm looking at getting a full size cap screws all over the water pump, fan pulley and cam covers, anything a can really, i'm a big fan. I'd even go Torx Button Heads but availability isn't that great.
Tim can you remember the bolt thread off the top of your head and i'll look them up and compare them with the hex head bolt's diameter. ( i haven't got the car here to measure). Generally the dia of a cap screw is the distance across the flats of a hex head.
Last edited on 11-09-2016 08:19 am by qwerty