[100IH]

With no arrow indicating front, it might not matter. On the mod. A, many were slotted on one skirt, those had to have the skirt oriented correctly. I don't remember which way, but if the machinist installed the rings and piston and rod assemblies he no doubt was familiar with the issue. I must add that I agree with the post about not advancing the spark to the full stop position. I go with just enough advance to get satisfactory performance, more is not better, just hard on the crank & bearings.