Do I need a small base circle cam?

[Rannos]

At what point do I need a small base circle cam in a 6" rod 383. The cam I have settled on is at solid roller thats .585 I .591 E and will lash to .569 I and .573 E 248*I 254*E @ .050 on a 110lsa Intake opens at 37* BTDC and closes at 69* ABDC Exhaust opens at 32* ATDC and closes at 80* BBDC. Would this cam and rod selection have clearance issues? If it helps to know the rods are Scat Pro Comps.

[Marv D]

It depends on the rods, the base circle, the lobe profile and how anal you are about clearance. A rod that uses cap screws will typically offer more clearance than the typical 'rod bolts and nuts' configuration. I have ground the CRAP out of both to get clearance in 383s and 434s with and without a small base circle. The cam lobe and timing is the key. There is some formula Jay Allen told me about the lobe vs. standard and small base circle. I'll see if I can find it, but in the end you'll not know how much grinding you have to do till it is in the block and things start falling together (or not)