This video shows the firing order/interval of the Ford GAA, GAF, GAN engine.
This is an odd fire engine, thanks to the flatplane crank and 60 degree bank angle inherited from the V12 it was based on.
The firing interval of this engine is R1 120º L2 60º R3 120º L1 60º R4 120º L3 60º R2 120º L4 60º
My limited research suggests that the GAA, GAF and GAN were all fairly similar, and were used in the following vehicles (tank spotters feel free to correct me in the comments)
GAA: M4A3 Sherman, M10A1, M7B1 Priest
GAF: M26/M26A1 Pershing, T28/T95 Super Heavy, M45
GAN: T23, M4A3E2
For this video I paused at ~800 RPM as this is a likely idle speed, 2200 RPM as this is peak torque, 2600 as this is the speed they were governed too before going to high RPM and back.
