The problem with using anything shorter than a 6.200 rod in this combination is that the counter weight of most after market cranks will hit the bottem of the piston. The best way to build this combination for balancing, longevity and performance is to use the 6.200 or 6.250 rod. Like mentioned before they still do not have a great rod angle. When the piston is at bottem dead center and the crank starts back up you have more side load with the shorter rod and this is hard on the pistons, cyliders and the rings. If the longer rod caused some kind of problem with the piston then we might want to go another way. The piston design with the 6.200 and 6.250 rods is great and the pin does not get into the
oil ring or even close with the top ring down .250 and 1/16,1/16,3/16 ring package. These are all of the reason for using the longer rod in this combination. It has worked for over ten years great and will work great from now on. I like the lighter piston and the ease of balancing if nothibg else. Hell you can make 600HP on pump gas with one of these combinations anyway. Good luck Keith Craft