[Amc-list] Adjusting non adjustable rockers (noisy on startup)

["Bruce Hevner" <scramblr@xxxxxxxxxxx>]

>Bruce, 
>On engine with adjustable rockers I would assume that this spec. 
>would become somewhat important, but on an AMC engine with 
>non-adjustable rockers or valve lash as it might be referred to it 
>is not obvious to me what one would do about this specification 
>unless I were to somehow verify that the lifters or push rods were
>the correct length which would probably be resolved by inspection 
>and comparison prior to installation. 
John 

Jon,
Good question.
Even engines with "non adjustable" rockers should have dry lash checked
and most CAN easily be adjusted. 
On engines with "pedestal mount" rockers you can reduce lash by grinding
the bottom of the pedestal or increase lash by shimming the bottom of the
pedestal (actually shims are available for this very reason). This would
apply to either individual mount or shaft mount rockers. NOW if your
rockers are shaft mount and rest directly on the head you have a problem.
The easiest way to reduce lash on these motors is install longer pushrods.
You can't really tell what your dry lash will be by checking pushrod
length and comparing it to spec since other factors can change it.
Machining the block and head gasket surface and the finish depth of the
valve seats plus overall length of the valve can affect dry lash.
 There are actually different length pushrods available for many stock
motors to adjust dry lash. The 3800 Buick is one that I constantly had to
reduce lash on. I almost always used .030 longer pushrods on these motors.
Quiet as a mouse on startup!
Bruce Hevner

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