I usually set my old school Atlas and Kato engines (the fastest on the block) to a top value of 128 and mid range at 98. Slow speed motors get 154/128. If I've got a real rocket, it gets 98/72.
If I do momentum at all, I give it an acceleration rate of 4, maybe 6, then set the deceleration rate at half that.
29 get's set at the factory value, unless I wired the motor upside down, then it gets 35 to reverse the normal direction.
Lee