ORIGINAL: Safebet
jb86:
I set the engine from the drive washer to the firewall just as the instructions said. I had to shim it out 1/2" in order to make it work. It is a J-3 GP and the engine
is a Saito 56. From memory (and that can be bad) I think it was 5 1/8 or 5 1/4 inches. I know it measured just what was called for. The cowl is pressed tightly onto the
nose, so I can't push it any further back.
I have decided to find or use a 1/4" pc. of laminated plywood with some 80 - 120 grit sandpaper glued to each side for holding power. I think the wt. of
the shim will be negligable.
Thanks for all responses. This is a great forum.
I'd check my measurements again, if it were my plane. It would be easier to remount the engine than it would be to take that shim out and remount the cowl.
Moving your engine forward or aft even a little bit will make quite a difference in the CG. The weight of the shim itself won't make much difference, but the leverage of the engine being too far out or too far in will matter.
Double check the measurement from the firewall to the drive washer, just to be sure. It doesn't make sense that GP's instructions would be that far off.