So I built a 347 stroker and put it in 67 cougar.... Scat bottom end, edelbrock heads, scorpion rockers, edelbrock cam. Engine has about 2000-3000 miles on it. I was driving it home and the engine started tapping. I got the cat home and took off the valve cover...to my surprise... Broken valve spring??? Has anybody else had problems with edelbrock heads??? Any suggestions on what springs to buy???