Sorry for not being around. Out sick due over spiced meal I cooked. On day 3 and things still tossing and turning but finally improving. I got to go light on that Cumin.

As being over rich usually the extra fuel cools the engine it is going too lean that over heat them.

I have ask my co techs on the forum I manage here and one in Kentucky said he has only seen three engine to fail like Wilbur's. His shop is a lot larger than mine.

Personally I haven't seen any Briggs with thousand of hours on them but what I usually deal with the cheaper non cast iron cylinders anyway. I do have few clients that are approaching the 600 hrs mark. Most the engines I see with a 1000+ hours on them are Kawasaki and Kohler and they are larger ZTRs used for commercial work.

May this will help on the bolt pattern. It is a little heavy on measurements you should still be able figure it out. Meanwhile I got to go back to the restroom to throw up my socks.
[Linked Image from thepowerportal.com]