Rubbish. 12 months of regular driving and .48 lift before I broke a valve spring.

yeah but if you replaced them they wouldn't have broken!

Philbey that's pretty interesting. I thought the springs started coil-binding above 0.4" in which case they would bend something quite soon. I suppose there is quite a safety margin in the cam grinder's figures.

 

These are in a 5K head, but keep in mind that I used "4K springs" for my 5K. Unless 4K springs are fatter than my 5K ones, or the 4K spring pockets aren't as deep, then it should be all the same.

 

At the end of the day, you still must measure up and calculate what is correct for your engine.

 

yeah but if you replaced them they wouldn't have broken!

 

Your point is...?

 

There's a difference between a coil-bind failure and spring fatigue, it was a 25 year old spring haha.