There's also a basic difference in the intake manifold. Chevy uses the intake manifold to seal the lifter valley. Pontiac does not. This causes the chevy to always run hotter intake charges than the Pontiac.
In essence, there are two basic firing orders for standard "90 degree" V-8 motors. Then, there are what are known as 180 degree V-8 motors. These don't sound right at all.
