The carb fasteners don't get torqued all that much. I think maybe 10 ft. lbs. which is a good hard twist with a screwdriver. In reference, a spark plug with a washer is torqued to 15 ft. lbs.

There is a Loctite product that is not as agressive as
the regular Loctite. It is designed for use on something
you might want to disassemble someday.

Andy the Toothed or serrated washers combined with your Girlies Nail Polish applied liberally to the threads will more than hold the Carb Intake Bolts . As for the Muffler I would use loctite it will ensure no bolt loosening . I would suggest that due to thermal cycles the threads are beginning to become a loose
fit class , which if you keep tightening will eventually strip out. The loctite will still allow fastener removal when req'd .

Use Loctite 242 (blue)

Well. I used the star washers and tightened the screws as tight as I dared. I ran the beast for about 10 minutes. When it had cooled down I was able to wiggle the muffler. I found some blue Loctite in my stuff and will try it tomorrow. I'm thinking of drilling the screw heads and safety wiring them together.

Andy , Loctite will suffice , but if your really bored safety wire them . As i said the threads are apparently shot , it's routine on many exhaust manifolds on small engines where what you have continued to do makes the problem worse . Proper lock washer or thread locker would have prevented this , but that hindsight lol . If all else fails you will have to drill out your block and retap the holes over size. Old Blowers are notorious for this problems . That and Helicoil for the Spark Plug Threads.

I blue loctited the screws this afternoon. I cleaned up the screws on a wire wheel yesterday. I ran the ngine for about 5 minutes before removing the screws and gooping them with thread locker. There were no lock washers on the muffler when I found this engine. The screws tighten up fine, there is no hint of stripping up to 25 foot lbs or so. If I have to re-tap, what size do you recommend?

I did not mean to imply negligence on your part for the lockwasher issue Bro ! But many people continue to overtighten Fasteners . In a perfect world every fastener has a proper Torgue Sequence and Load. The Intake Manifold of the Carburator was the Serrated Washer Cure that I was referring Too. Loctite was the Cure for the Thermal Cycles that the Muffler Studs are subjected to. As far as having to tap out the Threads I really don't think you will have to if you actually could torgue them as stated. If you ever have to drill and tap refer to a Tap & Drill Chart . Drill to the next closest size over to the Original and use the appropriate tap from the Chart. I love Old Machines & you will too if your have enough patience and Common Sense..All th Best let us know how you make out Bro !

Heh heh. Sorry, I was feeling feisty. I'm just a shadetree hack, but I've been hacking for 50 yrs. Plan C is to run 8mm coarse thread bolts into the 5/16, The bolts' pitches are quite close. 5/16" = 7.9mm So an 8mm is a tight fit. I've done this before in steel drilling out sheared 8mm bolts. I didnt have an 8mm tap, so I tapped the holes with 5/16. With a little oil and some patience, I chased the holes with 8mm bolts.

Hey nothing wrong with Shadetree Hacks Dude ! Some off the best ideas have came from some of my Buddies who are back yard mechanics ! It never surprises me , what a little common sence and patience can provide . Sounds like Your Ole Ariens has a good home all the Best ..Ty !

I must have fixed real good. It hasn't snowed since I loctited the muffler screws.

Andy: I hear ya Dude , isn't that the way it always goes lol . :)