whack needs the sides of the mouth to expand as the wh is pronounced and the ck is short as the mouth resumes normality.

Now, how to pronounce "owr" as in the Black Country "owr kid"? Well ignoring the Brummie upstart derivatives that bear no emotional connection with "owr die-alect" it is nearer to "Ah" and "a when verbalised, than "our" as in hour, but if yoh doh spake it rarght they doh understand yoh.