glen,
the gap or space between the end of the rocker arm and the end of the
engine's vales is referred to as valve lash. it is adjustable on vehicles
with solid (non hydraulic) lifters as in our little cars. the clearance is
rather critical and is measured with a feeler gauge of the correct thickness
per the specifications for the engine you are working on. usually intake
valves have less clearance than exhaust valves. the reason being ...exhaust
valves get hotter than intake valves and expand more that the intake ones do
so they need a little more clearance. now too much tolerance or clearance
and your engine would have a clattering sound on the top end similar to an
old sewing machine. too little tolerance or clearance and you will have a
rather quiet engine but it will run very poorly since after it gets hot the
valves will not seat properly in the head and eventually will lead to the
condition referred to as a burned valve. burned valves are not a good thing
to experience! this leads to an expensive bill at an automotive machine
shop to repair the damage from the valve burning.
the actual adjustment is not very difficult to do. grab a shop manual and
read up carefully on this operation. it was considered a "routine"
maintance procedure at one time. now it is frequently overlooked. but an
engine that seriously needed a valve adjustment will seem much more
responsive and seem to have more power after a proper adjustment of the
valves....and it will sound much quieter too.
hope this was of some use to you in explaining what needs to be done where?
chuck.
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