Big cam issue??

[Ricochett]

I have a 427/390 motor with the 063 heads! im going with a 639 lift roller hyd cam, and i was told that!,The valve guides need to be cut down! why would that be needed??? have anyone ran into
this before?
Thanxs Ricochett

 

[Hib Halverson]

A cam with .640-lift may require the valve guides be shortened.

What's the rest of the camshaft specs?
What rocker arm ratio?

 

[Ricochett]

Big Cam Issue

Hib

The cam specs Duration@050 inch lift 236 int. / 245 exh
advertised intake duration 335
advertised exhaust duration 339
Exhaust valve lift 639
Intake Valve lift 625
lobe Separation ( degree ) 112

Stock rocker arm ratio of 1.7

The cam is a Rolller Hyd. cam Edelbrock # 2261