Dumb question. what are the letter definitions in relation to the dimensions? (R*F* W* etc) :confused:

http://www.edelbrock.com/automotive_new/mc/manifolds/race_ref_dimensions.shtml

Not that dumb a question ;)
They are rarely used by most unless you do some hefty port mods ...

R = Bolt hole (to the manifold) centerline to port Roof
F = Bolt hole (to the manifold) centerline to port Floor
W = Width of port at manifold gasket surface
H = Height of port at manifold gasket surface
CH = Carb mount Height
CA = Carb mount Angle

Thank you!