At 09:59 PM 1/6/98 -0500, Andy writes:
>To the collective knowledge of the list,
>
>Oversize pistons with rings are available in .020 obviously for use when
>the cylinders are bored .020 over. As ring are available in .010, .020, .030,
>does this mean they are a substitute for oversize pistons? If so why bother
>with oversize pistons? (rhetorical). I guess the real question is, what are
>the pros and cons of just using oversize rings versus pistons.
>
>Andy
Andy,
Yes, there are such things as oversized rings. However, they must be fitted
in conjunction with oversized or knurled pistons and not used to correct a
worn bore by themselves. Generally speaking, piston-to-wall clearances
normally run between .0008" to .002". Greater clearances will result in an
audible noise as the piston "slaps" the side of the bore. The reason for
this slapping is that the thrust is on one side of the cylinder during
compression and flips to the other side on the firing stroke.
Also, since oversized rings are designed to be fitted to oversized pistons,
fitting them to standard pistons would result in the ring not protruding far
enough into the groove on the piston and would not be an effective seal
against the compression.
Regards,
Brian Schlorff '64 TR-4 '71 TR-6 '72 TR-6 '79 Spit
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