Hey Larry: I wish I were a wise one! My cylinder guy told me that most of
the C-65 thru O-200 cylinders he works on have weak valve springs. I had taken
the cylinders off Ken Doyle's Air coupe (Alon) and sure enough, the springs
on cylinders that were overhauled 800 hours ago, measured at about 1/2 the
required pressure. He told me that he felt that there were two major problems
that caused the sticking valves. First was too rapid a hone job on the guide
(assuming the correct guide was installed) and second was the re-using of the
springs. When you measure the spring tension, if it is even close to minimum,
replace them. I think the total for all four cylinders was only about $80
for the springs. (Remember, SERVICEABLE is only good enough to get it out the
door, not to the next overhaul)
He did have to replace the exhaust valve on one cylinder due to not
being able to get it to seal properly.
The rapid honing (or tired hone) causes the clearance to be slightly tight.
Making certain the clearance is correct or slightly more drastically reduces
the valve sticking tendency.
Lynn Nelsen
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