Im attempting to drill EFI bung holes in a cast iron or AL slant six intake. Im cutting them 45 degrees off the runner and I dont have a mill, only a bench drill press. Im thinking maybe the hole saw with a long pilot bit would reduce the chance of bouncing the bit off the runner when started, but I have had less than good results with hole saws and metal. I think the last hole saw I had was tweaked as the cut was not uniform, seemed to wobble on the mandrel, ended up just holding the piece and letting the hole saw move it side to side as it found its groove. Also would a bi-metal hole saw work on cast iron? Im leaning toward the hole saw but if anuyone has a better idea, Im game. Its going to be a 3/4 hole to epoxy (in iron) or weld (in AL) my AL EFI bungs. I have seem posts where the guys just drill a 3/4 hole and lean the drill over and let it cut down to 45 but that seems ghetto and I need these to be inline fairly accurately. Thanks.