Or the compression's going to be really high :)
Actually as this is about vibration, has anyone ever had experience with the Ballancemaster rings. They are used on Harleys to smooth out the vibes and also to ballance truck wheels tailshafts clutches etc.
On the Harleys they machine a ring in the flywheel and they glue it in, what it has is a plastic ring containing an amount of mercury, from what I've read it makes quite a difference, and if I can get one a suitable size will try it in a 90deg A65, which are pretty smooth anyway, but it would be nice to get ballance shaft smooth without the ballance shaft and performance loss.