All Small Six Adjustable Rocker's Adjusting Screw Issues

[TrickSix]

I picked up an adjustable rocker shaft assembly for a big log/big valve head I'm building. It has the tight friction fit no lock nut adjusting screws in it. I noticed while I was cleaning things up that some screws had a much tighter fit than others. So tight in fact that I was concerned the torque needed to turn them might do damage to the assembly. The looser ones make me wonder if they will stay put over time as the engine runs. I also noticed that switching screws from one rocker arm to another can result in very loose fits or even tighter ones. While not a showstopper, I'm not happy with this situation. Is it normal to have a more or less custom fit for each of these screws? I see a different two or three digit number stamped at the screw end of each arm, what is that for? I have also seen lots of pictures of these adjustable rocker arms with a locknut on a different headed adjuster screw. That seems like a better arrangement. They look very much like the Ford FE adjusters. I have not seen any I6 friction fit replacement adjuster screws advertised for sale, but have seen lots of the FE screws around. Are the two screw types interchangeable? Maybe with a re-tap of the threads to loosen them up a bit? Please advise.

 

[bubba22349]

Yes over the years Ford used two types of rocker arm adjustment screws on their different engines a friction fit type was used on the later model engines and the earlier lock nut system were used on the Ford Y Blocks and FE's and 223 Six'es for example. The reason that the friction type hold well is that the rocker arm has a kind of an egg shape to grip onto the adjuster screw you could use a press to gently tighten those up on the looser rocker arms again. As far as finding replacement adjusting screws most of the auto parts stores used to carry them however now days that might be a bit harder to locate. The FE or Y Block adjuster screw might work if you want to go that way but that can add to the job of setting the valve lash correctly needing to use both hands for a screw driver and a wrench. You could contact Rocker Arms Unlimted also to see about replacements adjuster screws of either type or even send them your rocker arm assembly for a rebuild they really know their job. Best of luck. http://rockerarms.com

 

[TrickSix]

Thanks for the info. I think I'll just run what I have now. I won't be making adjustments very often. My engine has hydraulic lifters, and the adjustable rockers are just to make up for head milling, different valves, etc.