If the piston has a "front" notch, it's because the wrist pin is offset slightly. This allows the piston skirt to preload itself against the cylinder wall during the compression stroke. Putting one in backwards will cause the piston to be in a "floating" situation as the spark plug fires, and it will slap the cylinder wall. It's hard to see the offset, it's usually less than 1/8", but it's vitally important to a quiet-running engine.
Jerry

Back the torque off the main bearings one at a time, and see if it's just the rear cap that's making things tighten up. Did you go through the shim-checking procedure one at a time on the mains as you assembled things?
Jerry


Last edited by Hotrod Lincoln; 01/27/2011 5:15 AM.
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