Spark plugs and other engine questions
Hi everyone. Well, the saga continues. I removed all of the plugs (AC-Delco 4I-906). They all looked very good. I gapped them all to .050. Fired it up and there was no change (maybe a little worse now). Review: Idle pretty rough (I wish it was because it had a radical cam, but no) - kind of choppy and inconsistent. Was thinking bad gas - but haven't driven it enough to use up the tank - hope to fill up with 93/94 Sunoco soon - addition of some old octane boost made no difference. Any "heavy pedal" and there is pinging under load. So I checked for arcing last night (idling in the dark) and noted what I initially thought was arcing but upon closer inspection it looked like the porcelain was just lighting up for about 5 of the 8 plugs that I could see from the top. I don't think the porcelain is cracked but I guess anything is possible. I am going to go ahead and get some new plugs but would like some advice on what to get. I have seen reference to Autolite 103/104, NGK TR55, Bosch BP???, AC-Delco (Rapidfires?), and maybe some others. In my case, I have a mildly built '93 LT1 block with a '94 ecm, intake, etc. At one time it ran great. Suddenly it has developed this weird idle and pinging under load. The fact that the plugs all looked pretty good (light tan and no evidence of buildup) leads me to believe I can rule them out. So, after replacing the plugs, what would be the next logical place to check. Oh yeah, I am getting no codes or SES.
Thanks,
Greg
