Original Posted By: H RULE
Re: Pietenpol-List: corvair disassembly, spark plug holes
Pietenpol-List: Re: corvair disassembly, spark plug holes
Original Posted By: Frank Metcalfe
Properly installed is the key phrase here...When solid inserts fail (regardless of their material), as they sometimes do, theytend to weld or bond themselves to the threads on the spark plug. Upon plugremoval, the failure mode results in torn threads in the head, along withmany issues - and expenses - for the mechanic or owner repairing the subsequentdamage. Consider the issues involved: teardown, welding, machine work to rethread,and reassembly. OUCH! Not a good thing. In my experience with aircooled engines, I've encountered just this, and it wasboth costly and time consuming.In the case of a traditional cylinder-head setup found on an aircraft engine, onlyone jug needs to be removed to correct this type of problem. In contrastthe corvair has a three spigot "log" head, requiring the full bank - or at leastthe head on that bank - to be removed and repaired.FWIW, I've repaired using both inserts & helical wire inserts, and there's no wayI'd ever do another critical repair using an solid insert. (Note the mentionof helical wire... theres an alternate to the Helicoil branded inserts, madeby Kato, and their insert and insert methods are superior to Helicoil brand.)If you don't know how to properly insert a helical type insert or have the toolsneeded to insert one, take it to a competent mechanic who will do it for you.Just my 0.02.--------Tom KreinerRead this topic online here:http://forums.matronics.com/viewtopic.p ... ______Date: Sun, 25 Apr 2010 09:05:26 -0700 (PDT)
Properly installed is the key phrase here...When solid inserts fail (regardless of their material), as they sometimes do, theytend to weld or bond themselves to the threads on the spark plug. Upon plugremoval, the failure mode results in torn threads in the head, along withmany issues - and expenses - for the mechanic or owner repairing the subsequentdamage. Consider the issues involved: teardown, welding, machine work to rethread,and reassembly. OUCH! Not a good thing. In my experience with aircooled engines, I've encountered just this, and it wasboth costly and time consuming.In the case of a traditional cylinder-head setup found on an aircraft engine, onlyone jug needs to be removed to correct this type of problem. In contrastthe corvair has a three spigot "log" head, requiring the full bank - or at leastthe head on that bank - to be removed and repaired.FWIW, I've repaired using both inserts & helical wire inserts, and there's no wayI'd ever do another critical repair using an solid insert. (Note the mentionof helical wire... theres an alternate to the Helicoil branded inserts, madeby Kato, and their insert and insert methods are superior to Helicoil brand.)If you don't know how to properly insert a helical type insert or have the toolsneeded to insert one, take it to a competent mechanic who will do it for you.Just my 0.02.--------Tom KreinerRead this topic online here:http://forums.matronics.com/viewtopic.p ... ______Date: Sun, 25 Apr 2010 09:05:26 -0700 (PDT)