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Posted by David Sherman on Friday, July 10, 2009 at 23:55:07 :
In Reply to: Speeking of slant six's,,, posted by Mr.PG on Friday, July 10, 2009 at 21:58:49 :
I had a friend with a Dart years ago who drove it around as a "slant 5" for a long time. Something bad happened in one of the cylinders, I don't remember what, and so he just pulled the rockers off of the bad cylinder so the valves would stay closed and it wouldn't waste gas, and he was done with it.
This one's a puzzle. A stuck ring should cause low compression, right? I assume compression is good both wet and dry. If the ring was bad, compression would be low dry, but would come up if you squirt a big slug of oil into the cylinder. Just to get the same answer a different way, you could try a leakdown test on it. Still, I'm thinking the cylinder is mechanically good.
That leaves spark as the most likely problem. Somehow that one plug is not working right. I assume you've looked at the distributor cap closely to make sure no cracks or bad pitting on the #6 position. A wire with "good" continuity (whatever that is for resistance wires -- a couple thousand ohms?) could still have insulation breakdown or leakage causing the spark to jump out of the wire, or could be intermittent at one end or the other and just happened to be touching when you checked it with the meter. It would be easy to run it in the dark and look to see if you see sparks or glowing under the hood anywhere. Might also try swapping in one known-good wire from another vehicle temporarily, or even swapping two wires on this one to see if the problem moves to another cylinder. Sometimes a timing light placed over the wire near the plug will fail to flash if the plug isn't sparking properly. Might be an easy test. Next step up electrically is take it to a shop that has an ignition oscilloscope that will let you compare waveforms on all the plugs. I'm usually against shotgunning things, but plugs, wires, and cap are pretty cheap and if you can't find anything visually or with simple tests, you might need to just replace it all. Is there any way that just that one cylinder could be running too rich? I don't think so, but if there was, that would cause a wet plug.
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