When I fired up my 454 for the first time over 10 years ago, I couldn't get it to run whatever I did. Huge backfires and massive flames out the carb. Tried all afternoon!!
Turned out I had wired the plugs as per Ford or Daimler V8, my only V8 experience up to then. When I made a phone call and found out Chevys were different, it started first turn of the key...
Chris