The gross HP of the SD-220 is 100, and the net HP is 90, both figures measured at 3600 rpm…which is also the maximum recommended rpm.
Original spark plug recommendations were AC 45 Commercial, Champion J-8, or Autolite N-7, gapped at .028″-.032″. Ignition point gap is .018″-.024″, dwell angle 31-37 degrees, with initial timing set at 2 degrees BTDC. recommended valve clearance setting is .018-.020 HOT. These specs are from the CTS-11 factory technical service manual for L-series trucks.