My mate has snapped two pairs of these cranks.There probably good cranks if you were using them for light comp use but i dont know why anyone would bother knowing that there prone to cracking after a short period of time. And no he hasnt snapped any other crancks eccept tensile.
Try not to gap down to the gap , pretend your doing a flat gap , aim for a point you want to gap to on the same level as the wall. That dont really make sence but maybe you will understand.