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Rocker arms

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Rut

Rut

Obi Wan
Offline
What's the best way to reface or dress a worn forged rocker arm? A couple of mine have small wear marks on the valve side and I would like to clean them up.
Thanks, Rut
 
As long as the valve stem tip wear in the rocker pad face is shallow, a polishing with 120 grit cartridge rolls, following the curvature of the pad will clean them up and not significantly change the shape of the pad and hence rocker actuation of the valve. Use machinist dye to help with know when to stop polishing.

If the wear is significant and can easily catch the valve stem (or your finger nail), then replacement is the only viable option. That is because the valve stem tip wear has worn through any surface hardening from the original manufacture.

Also, many machine shops have equipment that can resurface the pads as well.

Mike Miller
 
Thanks for the info. Do you mean 120 grit or 1200 grit? A couple of them have enough wear to catch the valve stem. After they are polished out do they just need to be re-heat treated?
Thanks again, Rut
 
120 Grit is the right grit. If there is more than say 0.010-12" wear, then serious consideration needs to be given to replace the rocker. You can polish out up to about 0.005-6" without significantly changing the profile. More than that and a machine shop really needs to grind on the rocker tip with a fixture that controls the pad profile/shape. I don't think you can re-heat treat the pad without significant cost and/or difficulty. The bushing in the rocker is fairly low temperature stuff and would have to be removed. Maybe an localized heating of the pad and oil quenching would work??????

I've got dozens upon dozens of rocker assemblies, that's why I just take the replacement approach. Find some with less wear and use them.

Excessive polishing also can bias the rocker pad in the direction parallel with the shaft. This pushes the valve stem and the rocker itself sideways in addition to the normal direction.

Mike Miller
 
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