Quote Originally Posted by Chaz View Post
Which produce a "slopabout" thread engagement ...

Plug manufactures know their plugs are going to be used in many different length's as well as used in both , aluminum and iron heads. And removed / installed .. hot and cold, so they purposely make them undersize. (measure for yourself)

Hardware stores sell you a D7 (read the tap) which produces a nice wallered out hole right from go ..

Chaz = thinkin, a 14x1.25D1 is the correct "plug tap"

https://www.mscdirect.com/basicsof/taps
you missed my pun...
PS thanks for the tap specs i didnt know about the tolerance differences.