Engine
It has been my experience over the past 50 years is that the scuffing above the top ring is caused by heat build up,
carbon deposits, and wear.
Combustion temperatures get high, add some carbon, and the aluminum piston is near the melting point.
so it tends to gall the piston to the wall at the top of the bore.
By design, the piston is slightly smaller at the top, above the ring, but as the piston wears, and the bore wears farther down, the galling takes place on the piston as it rocks in the bore when it is at top dead center.
On repairing the crank journal:
I have used a flat file to CAREFULLY remove the aluminum that is galled on the journal, successfully many times.
but it has to be done carefully so you are only removing the alum, not iron journal .
if you use emery cloth you will remove both, --not good
another trick is to use acid, it will eat the alum. but not the iron journal ( wish I could remember the name of the acid) but they use it to clean alum. wheels. ( sulfuric acid works also)
acid takes a little longer to do, as I dab it on and go do something else, checking back periodically.
---the acid works well on cylinder walls to remove galled alum. in 2 stroke applications.
On the head Gskt:
They usually blow right above the exhaust valve as that is where the most heat is.
check your head for flatness, and if need, surface it and proper torque is very important on those engines, retorquing several times after it has been run @ operating temp.
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