I have a 305 that I want to put Comp cams magnum 1.6 roller tip rockers on but I don`t know if they`ll make the retainers hit the head. The heads are just normal 305 heads with some intake work done to them. the cam is a Crane 272 H10 with .454" lift.

 

What valve springs do you have on those heads? If they're stock, forget it. You'll need new ones.

 

they are Crane single coil springs there WAY stiffer than the stock springs, I bought them with the cam because they recomened them because the stock springs were way to weak to handle the lift and they had 285000 km on them