Originally Posted by Hotrod1979
Thank you for your reply.
Looks like the Dart heads are stock. Are you sure this is why these springs failed?
I will take one spring out and do some measuring...
I am not sure what kind of cam I have got..
I'm not convinced that the spring seat size was the cause of the dampers breaking. Might be third or fourth on my list of probabilities.
Not knowing anything more than what you know at this stage (which is limited until you can dig further), I suspect floating or lofting the valves. This can happen even at lower than expected rpm if the springs aren't right for the application, or have a too-tall installed height, or are faulty from the factory, etc. Besides the pounding the springs take when that happens, this also sets up harmonics that can break dampers and springs (spring surge). That has been associated w/dampers breaking, and I have had this happen on engines w/insufficient valve spring pressure for the rpm/cam profile being used. 1.6 ratio rockers can magnify this.
In any event there's MANY things that could cause the damper to break, not just the spring seat size. Even a bad batch of spring dampers can cause it, like I went through with the K-Motion springs I was using a while back. They finally redesigned the damper (has a reverse coil from the old ones) and problem solved.
I prefer to use an ID spring locator. But regardless of what you use (spring cup or an ID spring locator sized to the guide boss), the spring locator HAS to be a close fit to either the guide boss OD or the ID of the head's spring cup, else you're no better off than you were with no locator, period.
The MAIN thing is to have a spring that's spec'ed for the cam and rpm, and to not exceed the redline. If you can do that, you can leave the locators on the shelf.
• Valve spring installed height
• Points to check
• Adjust lifters