By open do you mean bypassing the fins on the underside of the intake manifold or diverting the hot exhaust gases to the underside fins of the intake manifold. A picture would help.

__________________
Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.