Here's a bit of info I learned today and I will add to the engine instructions.

When attaching the prop if you use a thick prop and/or spinner backplate measure how much thread is left on the bolts. The prop bolts must engage the hub at least 1/2" or you run the risk of stripping the threads.

If your prop. backplate and any washers leave to little of teh screw protruding out the back you must replace the bolts with longer ones. I have longer bolts here, they are 5mm x 45mm, or you can get them from Microfasteners.

If you strip the threads on one bolt, stop. You may be able to recover from it with longer bolts in all 6 positions.

TF