Spark knock issue

Old 09-27-13, 03:29 PM
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Spark knock issue

I drive a 1985 dodge d150 with a slat 6 engine, when i bought it the truck idled real low and would shut off at an idle occasionally. I adjusted the timing by ear due to the fact that the timing mars are gone and did a complete tune up, rotor, cap, plus, wires, oil. the plugs are gapped to factory specs. i can't get it to quit spark knocking and its running rough. Any ideas on what to do?
Old 09-27-13, 04:28 PM
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You need to get the timing set properly, most engines especially from that era don't tolerate a blind guess about ign timing. You can re-establish TDC with a pencil and a socket on the engine crankshaft. By turning the engine by hand and feeling the piston in #1 cyll coming up you can find where true TDC is and establish a mark. Thats how we used to do engines when building them. It's a good guess you have the timing way early and that's what is causing the issue so retard it in increments until the noise is gone or you can use premium fuel as that will also help. The cylinder heads of that era had poor chamber design hence they were unforgiving to stuff like this. You can also use a vacuum gauge to help determine where it needs to be.
Old 09-27-13, 05:29 PM
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Also make sure your plugs are the proper heat range and that your egr valve is clean and operating.

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