Why wasn’t what explained. That the chambers that I usually Dont have to touch on a Speedmaster head was unmachined. Or when I went to do the final valve job I found the intake valve guide to be .0025 to big. Their guides are usually fitted better than Edelbrock heads. It cost my customer a little time (on a set of heads I did past my race season cut off date) it cost me out of pocket money for work I do pretty cheap compared to others. Head porters learn daily just like others.