The bolt in place:
There just isn't 1/6 turn space with an open end wrench.
I also tried 5 different brands of box end wrenches, none fit.
Quick trip to the hardware store for a 1/4" x 20tpi x 3/4" length socket head cap bolt and washer.
Ground off the end of my only 3/16" hex L wrench. Something I didn't want to do but... There is just 1/6 turn space for the hex wrench. A pair of needle nose pliers got a little grip on the serrations on the bolt head to get it turned in most of the way. Then finish with the hex wrench and a cheater bar to get it tight.
Ran out of light and heat so I called it quits for the night. and then, it hit. 5 inches of snow over night. I'm not done with this 1962 PowrKraft snowblower engine tune up so the newer Cub Cadet got the call to clear the driveway this morning.
I now see on the www there are Briggs hex wrenches. 3/16" and with longer and padded handles. I'm guessing Briggs made a switch to hex socket bolts for some engines due to this inaccessibility problem.
The Stanley Yankee ratchet sideways screw driver doesn't quite work as the head just takes up too much space. Can't get the blade centered in the slotted bolt head.