I was buying rocker arms for a 455 recently. I found that the originals were of "Left" and "Right" designs based on where on the rocker shaft they were positioned. However, plenty of web sites are selling 16 "centered" rockers instead of 8 Left and 8 Right rockers. What applications are supposed to have the "centered" rockers; or is that a cost-cutting shortcut the aftermarket invented to reduce inventory? I have trouble believing that "centered" rockers could be preferable to the L-R rockers.
No BBB uses centered rocker arms, although I have seen many that get mixed up in the boxes. I believe these to be factory defects. When I go buy this type of rocker I do one of two things.. buy from TA who catches this, or if I buy locally, I go down and physically inspect each and every rocker, to insure it's correct. Always several have to be changed out. Melling part numbers are MRK542L and MRK542R They will be stamped left and right, just like the factory ones. Look specifically at the pushrod location, I have seen more than a few that are stamped R, and actually are centered. The L rockers seem to be pretty good in my experience. If your buying online, I strongly advise that you buy from TA, they know all about this and catch it.. Their part number is TA 1317 for the set with shafts, but those are the stamped steel rockers your talking about. They list them individually, but without a PN. Good luck JW
Would these stamped L and R steel rockers be preferable to the 68-69 rockers? I had begun a search for the 68-69 units after a comment in another thread(mostly because I'm too cheap to spend the money on the roller set, I don't see the benefit for that much cost).
Generally, stamped steel rockers are fine with up to 300 lbs open pressure and a normal open/close rate camshaft. they fail when a pushrod goes right thru the cup.. The 68-9 rockers are much stronger in that area, but can have issues breaking the tip inserts. But they are considered more desireable than the stamped steel ones. With the 8-9 rockers, you will need a hybred pushrod, as they have a 3/8 ball seat.. larger than the later pushrod tips. JW
I will double-check my supply of rocker arms to assure they are actually what they claim to be. I bet there's a Buick application that uses the centered rockers--maybe a V-6 or something. If it was just a matter of reducing inventory by making a more-generic part, I'd think the L-R arms would be discontinued and depleted years ago. I haven't checked the Melling rocker-shaft assemblies to verify that they use the proper L-R rockers, but I suspect they do. There is another issue I'd appreciate help with that concerns rockers and shafts. Somewhere, I read that the rocker shafts on a Buick should be turned "upside down" when doing a certain modification. Maybe this was required when going from thru-head oiling to pushrod oiling. Maybe it was when converting from aluminum rockers to stamped-steel rockers. Maybe it was a SBB issue, maybe BBB. I don't remember any details, just that the rocker shaft should be installed with the oiling holes in the opposite direction--up instead of down, or the other way around. Can you fill me in? Am I hallucinating? Thinking of Mopar instead of Buick? Bat-Shiit Crazy?
In that case the search will continue . Thanks so much for the info. Added: Reading this thread leads me to open the search up to sbb rockers. Would this be the right direction, or are the sbb rockers different than the BBB rockers? http://www.v8buick.com/showthread.php?319217-69-Rockers-350-vs-430
Cobwebs in my head from the old Buick dealership that I use to work at..... As far as I remember, the stamped steel "centered" rockers rolled of the factory lines on the 73 through 76 455's. The "L" and "R" stamped steel rockers were the service replacement parts. I no longer have access to my old service manuals to confirm. If you think the stamped steel "centered" rockers are a bad deal, many third party mechanics didn't understand or noticed the "L" or "R" stamp, and installed 16 "L" or 16 "R" stamped steel rockers in the same 455 engine....now that was a bad deal. I think the V-6 use the "L" and "R" stamped steel rockers from the get go, and never used the stamped steel "centered" rockers. Tommy
I've run into that issue years ago with mis-boxed rockers The "L" and "R" designation refers to the pushrod offset in the rocker so the pushrod stays somewhat centered in the pushrod hole in the head. Too many people think it refers to the right or left side of the engine, or the valveou:
