[bobcowan]

The big question, Why did it break? If you don't figure that out, you'll be breaking more springs, with eventual catastrophic effects.

True, sometimes stuff just breaks. But I would check a few things before pressing on.

The #1 concern would be too much valve lift. I would actually measure valve lift with a dial indicator to make sure you know exactly what it is.

Second, check for coil binding. With a valve fully open, use a feeler guage to see how close the spring coils are to each other. They should not be touching anywhere.