[A Snake]

A funny thing happened on the way to performance.

When Ford went to the Med riser, several things changed from the old low riser. The one you can't see with the intake on the engine is the port height. The ports are actually bigger on the low riser....at least visually. What changed on Med Riser is the floor of the port was raised about 1/4-3/8" to increase air flow. Same thing as "D porting" did for Chev heads. It is not a good idea to use a low riser manifold on med riser heads for this reason.

The mis match at the bottom of the port will create turbulence and disturb proper air flow. In short, it will steal power and give the owner fits trying to sort out why the engine falls on its nose at mid to upper rpm. Yes, the engine will run.....just not right.

Al