RE: 4-Stroke Mounting Question
G'day
Welcome to retirement. I have found it has much to offer. And it can be extremely busy.
I think you may have a Vess prop? If it is, it is probably a wooden prop?
Generally I don't use wooden props on four strokes. The greater weight of fibre filled props is of great benefit to four strokes as they only fire once every two cycles and the greater inertia of the heaver plastic props seems to help them smooth out. They can be quite inclined to vibrate as their power pulse is, particularly in larger engines like yours, quite a whack and this can make them vibrate in a less than rigid airframe. I do not use soft engine mounts at all.
Having said that, I generally don't use wooden props as our field is at best rough and it is too easy to break props there.
I'd suggest trying some other props. The Graupner props are really good if you can get them. Master Airscrew are tough and work well on four strokes but the APC are probably the best all rounders but quite easy to break. Sadly, my favourite prop, the Bolly Clubman series, is no longer made. They were really great on four strokes.
Cheers
Mike in Oz