It should be possible to set up a drilling jig on an engine block similar to the "deep hole" drilling procedure used for drilling the hole in a rifle barrel blank. It involves a long guide sleeve and a relatively small diameter drill bit to make a pilot hole (maybe 1/4" or so) followed by a series of larger bits with a pilot shank, or a special drill bit that is pulled, not pushed through the original hole. The setup time for the first block would be considerable, but the rest of them would be a pretty simple operation.
Jerry
