Fix for this?
I guess I could try to give you more answers. Many stroke/bore combinations actually pull the piston slightly out of the bore add that to the fact that pistons are clearanced for the crankshaft and or short skirt can leave a lot to be desired when in comes to keeping the piston from rocking in the bore= causing accelerated piston skirt/bore wear. Pistons to wall clearance can also cause this but due to thermal expansion of the piston there is only so much you can do.
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I guess I could try to give you more answers. Many stroke/bore combinations actually pull the piston slightly out of the bore add that to the fact that pistons are clearanced for the crankshaft and or short skirt can leave a lot to be desired when in comes to keeping the piston from rocking in the bore= causing accelerated piston skirt/bore wear. Pistons to wall clearance can also cause this but due to thermal expansion of the piston there is only so much you can do.
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After cleaning up a few piston tops, it looks like detonation has been occurring. Is this the typical skirt pattern seen from detonation? Possible lubrication or clearance issue? Cooling issue?
Last edited by DrX; Jul 28, 2015 at 04:30 PM.
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Cylinders measure pretty round and straight at 4.1275 +/- .0005 with the +/- being at the bottoms. Measured in 4 directions at 3 depths.
Piston skirts all measure 4.125 at widest dimensions. Land diameter is 4.084.
So I get .00125 for PB clearance?? (4.1275 - 4.125) / 2
Or is it just calculated as bore diameter - piston diameter? In that case it would be .0025
Piston skirts all measure 4.125 at widest dimensions. Land diameter is 4.084.
So I get .00125 for PB clearance?? (4.1275 - 4.125) / 2
Or is it just calculated as bore diameter - piston diameter? In that case it would be .0025
Last edited by DrX; Jul 29, 2015 at 10:12 PM.
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Cylinders measure pretty round and straight at 4.1275 +/- .0005 with the +/- being at the bottoms. Measured in 4 directions at 3 depths.
Piston skirts all measure 4.125 at widest dimensions. Land diameter is 4.084.
So I get .00125 for PB clearance?? (4.1275 - 4.125) / 2
Or is it just calculated as bore diameter - piston diameter? In that case it would be .0025
Piston skirts all measure 4.125 at widest dimensions. Land diameter is 4.084.
So I get .00125 for PB clearance?? (4.1275 - 4.125) / 2
Or is it just calculated as bore diameter - piston diameter? In that case it would be .0025
With a torque plate bolted on, the taper in the cylinders might go away.
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On both the bore and counterbore edges?
Depends. For a 4032 alloy, it's probably just right but since it's a power adder I'd assume it's 2618, which would be tight. I'm also assuming you're properly using a dial bore gauge and micrometer accurate to .0001" as well.
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I think it is probably correct at .005 PB, but I was reading the bore gauge(.0005) wrong. What threw me off was I used a dial caliper at the top of the bore as a sanity check and it was telling me it was under 4.130. Now it looks like that caliper reads around .002 under actual.