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Gentlemen
I believe I figured out the base cylinder seal / oil leak mystery. The O'ring seals which were installed in the groove of each cylinder base never had a chance to seal against the case spigot because the 4mm wide copper ring which was placed between the O-ring and the case prevented the O-ring from ever coming in contact with the case spigot and creating a seal. At least this was the case on the left hand bank of cylinders which leaked - the right side was dry so the copper ring was making a better seal on that side. I believe there is both pressure and vacume built up inside the engine case just from the pistons moving up and down and because the gap between the case spigot and the outside of the cylinder wall is so large in relation to gap between the cylinder base / copper ring / case interface that this was the path of least resistance for the seal, - hence it was pulled/sucked into the engine being shredded as it was pulled past the edge of the copper ring . The sealing in this area can be resolved by just putting in a new green viton O-ring and eliminate the copper ring but I believe the copper ring was installed to act as a shim in order to compensate for the over machining done on the heads. So my question is: How much below spec can be shaved off the heads before problems with piston to valve clearances arise? I know in the olden days on North American engines it was common practice to plane down heads in order to raise the compression ratio. Can the same be done on the 3.6L and if so how much? If I do the solder on top of piston method to measure the clearance between the valves and the piston what is the minimum distance recommended keeping in mind that metal expands when it is heated to engine temperatures especially in the combustion chamber.
All responses welcome
Bill
90C2
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