[C10 - C90 Bill]

Well, I found some of the conversations we had, but it really didn't tell us much useful info.

Info on the 503 is still hard to find out there. About the only thing I could find from a couple of different sites:

503 CDI firing order 142635 Spark gap .030 points .022 Timing 6 degrees BTDC. Timing mark is on the flywheel. Valve lash, intake .012 hot, exhaust .020 hot. Head bolt torque75 / 80 foot lbs. These specs are for a 1955 but are most likely the same as 53, if not they will be close.

The 502.7 (8.2L; 4 9/16" x 5 1/8") GMC inline six was more numerous than the 426 inline six.