Hey all I have an os .40 that uses two screws to mount the carb to the engine, and I was wondering if it would be safe to use a tiny amount of thread lock to keep them from coming loose. Also one seems to be slightly stripped out, but I can get it tight, I'm just worried about it coming loose during flight and causing a vacuum leak.

Clean the screws and threaded holes well with acetone and use red loctite. If you ever need to remove them, apply some heat on the screw with a soldering iron and they will break loose.

Yes, use Loctite on those screws, and in this case I agree with speedracerntrixie to use "red" Loctite due to the partialy damaged threads. For normal general assembly screws or nuts "blue" is usually recomended because disassembly can done with normal tools and no heat. I use Loctite on all critical bolts and nuts; engine mounts, muffler mount bolts, wheel collars,etc. I some times use loctite plus a lock washer, just making sure it dosen't fall off!! It works, so use it. As already pointed out the parts must be clean and oil free for it to work.

The blue locktite will do the job just fine, assuming you have good threads. All that locktite does though is keep screws from turning on their own. It's not a fix for bad threads. If you're confident that the threads are still good enough to hold, the blue locktite will keep the screw from vibrating loose just as well as the red will. But if your threads are bad, it's a simple process to drill and tap the hole up to the next bigger size.

If the threads are too buggered - step up 1/2 mm on the screw diameter and tap it - same pitch count. Used this approach on an OS 46 LA that was  aggressively over tightened by previous owner.

Thanks all.  I will have to track down a tap set.  Sounds like the best thing to do.</p>