GMC Repair: ignition timing, good old time, gmc 3500

Question
What is the ignition timing for 1977 GMC 3500 with 400ci.

Answer
Hi
Best I can discover is 5 degrees at 12-14" vacuum.
I would suggest maybe trying your local public library
or if you can find a real good old time mechanic
My books just dont go back that far.
Sorry I was not able to help you more than this.
Good Luck
Paul