PRW,Don't do it!!!!

i have had a set of these on my 340, then on my 418 . they been on here for 3 years, with a .637/651 solid ultra dyne. no problems. they are the 1.6 rockers, when i orig installed them on the x headed 340 i had to do some grinding so i had enough clearence between the spring retainers. i bought these because the were in my price range, i guess im a lucky one.