Therefore, a stock Chevy firing order of 1-8-4-3-6-5-7-2 becomes 1-8-7-3-6-5-4-2. To understand how this is done, you need to know about companion cylinders, which are the pairs of cylinders that ...

Found a great chart floating around the web from MSD Ignition on common firing orders for some of the most common Ford, Chevy and Hemi engines around.