dirtymac Posted June 16 Share Posted June 16 We were looking for something quick and easy to do this weekend. I have been waiting to swap the spark pugs until I install a new ignition harness but that is still a ways out. We removed and labeled all the plugs and they are pictured below. Each one had some amount of oil around the base/threads. Number 3, 4, 5, 6, 7, and 8 were on very tight. 2 wasn't even hand tight. 1 had been removed and re-installed a while back when we replaced the harmonic balancer. My understanding is that they should not be cranked down very tight. Each appears to be fouled to some degree but I can't decide if it is oil fouling, something related to the narrow gapping, or something else. The spark plugs are Motocraft ASF-42C and they were gapped much closer than the .042-.046 listed for the engine. Neither O'Reilly nor Autozone list these plugs for my engine (1982 400) but they are listed for similar engines before and after. Also, I have no idea how old these things are or what other problems may have been happening before getting the truck. I have replaced them with Motorcraft SP425X gapped to .042. Most came out of the box gapped correctly. The first image is of number 1 from when we worked on the harmonic balancer. I have other pictures of it but it basically looked the same then as it did today. Since it was last out, we have replaced the balancer and replaced the carb as the old carb had a lot of issues. The new carb could still use some work on the idle circuit. We have also added a factory air cleaner with proper valve cover attachments. The other images are the old plugs we removed. Link to comment Share on other sites More sharing options...
85lebaront2 Posted June 16 Share Posted June 16 All but 7 & 8 look normal for a 400, every one I have ever worked ran super lean. Link to comment Share on other sites More sharing options...
dirtymac Posted June 16 Author Share Posted June 16 All but 7 & 8 look normal for a 400, every one I have ever worked ran super lean. Is this something that should be addressed or is it more of something I have to live with? Link to comment Share on other sites More sharing options...
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