changing ignition coil

I had recently put an ignition coil on, in my 91 Park Avenue because one of the pins were not firing and the engine was misfiring. Once I put the new coil in and started the car the engine started knocking(not a ticking, a loud knock, like the engine is going to blow up). I was wondering if there was something I was supposed to do while changing the coil, could the timing of got off somehow by me changing the coil, or is this just a coincidence? This 3800 V6 has 249K on it. It purred like a kitten until I changed the coil. Another question; could the timing chain of slipped a notch or two, causing it to knock? Where is the timing chain located?

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