I just got a set of 1.6 rollers for my car, still stock, and i was wondering if any body out there had to drill their stock heads for 1.6 rollers. its a 91 305, and i really don't feel like drilling my heads. comp cams say some heads may need drilling. does mine? help me out here guys.

 

oh, and its the TBI cam, so so there's not much lift (TBI to TPI swap, no new cam).

 

drill what for what? there's no reason to drill anything to use roller rockers that i can think of.

 

On about half of the SBC heads I've ever worked on, the push rod guide slots were not long enough in the direction toward the stud to accomodate 1.6 rockers. The increased ratio is accomplished by making the distance between the push rod seat and teh stud shorter, which moves the push rod inboard. This change in the push rod location is enough that at least one of the holes interferes with the push rod. There's no way to predict what heads will need it; I've seen engines with the OE heads where every single one on one side cleared, and every single one on the other side interfered. It's strictly luck of the draw.

Your car has "self-aligning" rockers, which means that the holes are bigger anyway. You might get lucky.

The issue has nothing to do with rollers, only the ratio change.