Re: Damaged Valves & Pistons: Yes, no, maybe?



Your valves don't have indiscreet, clandestine meetings with pistons, if they come into contact you will know it.
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Thomas Moats wrote:
Thanks to you and Scott for replying.

Fairly much what Scott implied. While I am not mechanically challenged,
I don't get under hoods unless necessity dictates. I do not have the
empiricism to know if a slight timing change would allow a valve to make an only slight contact with a piston where it would still run but would cause performance damage (e.g. bent valve stem). I never heard any sounds of damage.

I had stopped but after some rudimentary investigation. While it was running with ample exuded black smoke (both exhausts), I heard at the tailpipes the "phhht, phhht, phhht" sound of open valve(s), seemingly only at the right bank. That with the OBD-II scanner timing readout led me to believe the timing was changed. Until the misfire (#6 wire to #3 wire), the engine was running just fine (66K miles). No diagnostic codes registered after I cleared the misfire code.
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You can advance the timing to 30 degrees, the pistons will not hit the valves. The mechanical timing between the crank and cam does not change.

depending
Black smoke is an indication of a very rich mixture. A bent valve will not cause that. The sound you hear is because of poor cylinder contribution ( you even indicate the engine is not fully correct in running only better ) most likely caused by an over rich condition. The fuel pressure may be way too high. When changing wires you may have knocked off or left loose a connector. Also I hope you did not just replace #6 wire, but all the wires and plugs. The problem is most likely going to be where you have been ( replaced wire ), look there.

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