The info is below. EXCUSE: I was working in poor light. I thought the base nut that holds on the screw/stud as the holder for the rocker assembly was the nut to loosen to allow changing the settings. I turned the top nut above the rocker for adjustment. What was happening is the screw/stud was moving because of the allen screw. I thought the stud was one piece and the allen screw part of the stud. I did not notice it was an allen screw. I saw the top as flat and the top of the stud - a major mistake.
After putzing for a number of hours I could get adjustments but not within the range of the spec. I posted on another forum and got the info below. That cleared up my mistake and the valves were adjusted in a few minutes.
BTW: I almost posted several days ago about this engine related to your posting several months ago about making a "Frankenblower". You mentioned possibly strapping on a V-Twin.
The one I worked on was a Kawasaki 15hp and it's wicked powerful. It was on a Scag 36 inch walk behind. I had never used one before so did not know the controls. Muscling a 13hp snowblower around is no problem and I thought the Scag would be the same. The Scag is 530lbs and it moves where it wants to even with yanking on the handlebars which can only be done for a very short time. It would make a wicked powerful snowblower.
I put a new 11hp OHV engine on an old Ariens 824 body. That body could take a 13hp. It was older so the rakes were turning at 100 or 110 RPM so not so fast. The 11hp was new so full compression and running at 3600 RPM like the 8hp but a big difference in distance because of the power. Wet EOD was no problem. Given how much more powerful the 15hp twin is it would probably do average snow 50-60 feet without much of a problem on that body. It would probably do the same with wet snow.
The twin’s smoothness was impressive. I could not get a tach reading off the handlebars or body. I had to go on top of the cowling to get vibration. Great engine.