JohnnyO brought up a good point about using the right springs with the cam. Always ALWAYS use the springs that the grinder recommends with his cam.

To take this a step farther, always use stock, STOCK, S-T-O-C-K springs for the break-in. I'm talking about just the outside single coil without any flat-wound damper or anything else. I used to keep an old set of worn-out stock springs on the shelf just for this purpose. Once the motor is broken in, replace the stock springs with the ones recommended by the grinder. Use shop air to hold the valve on their seats and use a Moroso valve spring compressor to change out the springs. It's not that hard to do it right.