Good Valve Spring Kit for AFR 165s

Letter cams are the laughing stock of the cam community. They are old single grinds from the early 80s. The bigger the cam, the higher the rev range, so your problem is only going to get worse. For the money you are going to spend on new valve springs you could get a custom cam. There is a guy on here with a convertible mustang who was running 12.5 on AFR 165 heads and a custom cam from Ed Curtis at flow tech induction. It was a 331cid low compression engine, though. Not sure exactly what the optimum lift to make those heads flow is going to be, but I'm sure that it's less than .550." You'd be much better off spending the money on the right camshaft.

The custom cam on my engine is only like .577" of lift and I'm running a very large set of Canfield heads on a 347.

Kurt