Hello and thanks for all the input but now I'm confused.I thought only Oldsmobile's had guide plates, Everything I've been reading says bring cylinder one to TDC, then adjust valves xxxxxxxx til push rods have no slack then another 1/2 turn then repeat for other 8 rockers, I put a mild cam in Cam - 214/224 duration at 050" // 444/466 valve lift Push rods - Comp Cams 7851-16 Rocker arms - Sealed power R-1032 New balls and lock nuts Melling valves 2.11/1.77 length 4.998" I'm adding pictures of 2 rocker arms, 1 from a 68 400 4bbl Firebird and 1 from a 67 326 I did order a set of the 67's and from the pictures you can see the height difference from the 2 where it's closest to the spring perch. The first from a 68 and second from a 67. One last note is that the valve's I installed according to Melling will not fit a 1968 GTO 400 2 barrel
