The shaker pumps work great. They can be mounted on the engine or the firewall inside or outside. The only important issues are the centerline of the pump must be at least 1 1/2" from the centerline of the crank and the pump must be mounted somewhere radial to the crank. That is to say as the engine shakes from side to side (not front to back) its motion will make the shaker inside the pump shake side to side (not front to back). They really are easy to mount and use. I have ran them on engines from 70 size to 180 size both 2 cycle and 4 cycle. I usually mount mine on the firewall under the engine but once when there wasn't room I mounted it on the inside of the firewall and it worked fine.