On John's 4 cylinder crankshafts the flywheel bolt holes just happen to be aligned with the connecting rod journals, so attaching a bracket for an offset center is going to be an easy job. Just measure off one half the stroke length and drill a hole in the bracket with a 60 degree center drill, one for each end of the crankshaft. On stovebolt 6 cylinder cranks like the 216, 235, 261, etc. those three dowel pins that index the flywheel are also clocked to match the three companion cylinder journal pairs. I also have a bunch of heavy steel counterweights to balance the weight of the crankshaft as it's suspended between the offset centers. Yes, I have a good assortment of 4 jaw chucks, and I use them almost exclusively.
On a stroker crankshaft, the shaft is offset to half the desired new stroke, the shaft is machined or ground until the shaft is round, and then it's metalsprayed back up to the desired journal diameter, if necessary and finish-ground. I believe I can offset-grind a 235/261 crankshaft to get an extra 3/8" of stroke, or possibly 7/16", depending on which connecting rod/bearing combination I choose.
Jerry
