I had a knock that sounded like it was coming from the
piston pin on the #1 piston so I pulled the motor and
tore it down. The pistons were stamped with a 1.00-F
marking on the top and there were small (1 cm) notches
in the edge at the front and back of the top of the
piston. I measured the pistons and got 87.75 mm. The
Datsun Sports manual I have lists a 100 overbore with
the size as 88.270 mm. Upon manipulating the rod and
piston I can find no slop at the pin. The rod bearing
has some very shiny worn places and an area where the
copper shows through. How do I determine if the pin,
piston, or the rod top bushing are bad? Why do the
measurements not match the factory manual? What are the
notches for? They don't appear to be valve reliefs.
These pistons appear to be three piece units with some
kind of inserts the wrap around the skirts on the
inside. I have a set of Jahns high compression pistons
that are the same size. I have not been able to find
out anything about them. They do have big valve
reliefs, but they didn't help the PO. All four of them
have impact marks form the intake valves. I was
thinking of grinding the impact area a bit and using
them. This car will be for autocross and I have access
to all the (free) aviation fuel I could ever need. (I
work for a lab that tests diesel/gas/jet fuel etc...)
Thanks,
NT
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