Hi, Jonny: Can you be more specific about the year and application of your 413? According to my files, A42 is equivalent to a Champion J12Y (the lower the Champion number the cooler the plug, it's ability to transfer heat resulting from combustion to the cylinder head quicker than a "hotter" plug. Cooler plugs are used in high performance engines.) Champion specs for a 413 list a RJ14Y for standard applications and a RJ11Y for high performance applications. A J10Y or A32 is recommended for a 1959 300E. For your info: R = Resistor plug J = First prefix letter for thread size - thread reach (3/8 inch) and hex size ( 13/16 inch) 14 = Heat Range Y = Gap style - protruding nose Since R,J and Y are given for a 413, the heat range is determined by application. If you run your 300 frequently at high speeds, a cooler plug is recommended. If you drive the car occasionally, I would suggest a hotter plug. Please advise the year, car and carburation: 1 or 2 4-barrel carburators. Maybe we can zero in on the right heat range for you. Other, more experienced club members may have additional or better information. Best regards, Ron Kurtz E# 292 ________________________________ From: Jonny Mattsson jonny.mattsson@xxxxxxxxxxx quicker To: chrysler300@xxxxxxxxxxxxxxx Sent: Fri, February 18, 2011 3:01:50 PM Subject: [Chrysler300] Spark Plugs Hi group, Some time ago,spark plugs questions has been asked,guess I delete them. However,the 413 engine specifications says Auto-Lite A-32 or Champion J-12Y. I have a package of Auto-Lite A-42. Can I use them? or what is your choice today. Jonny Mattsson Sweden [Non-text portions of this message have been removed] [Non-text portions of this message have been removed] ------------------------------------ To send a message to this group, send an email to: Chrysler300@xxxxxxxxxxxxxxx To unsubscribe from this group, send an email to bob@xxxxxxxxxxxxx or go to http://autos.groups.yahoo.com/group/Chrysler300/join and select the "Leave Group" button For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm For archives go to http://www.forwardlook.net/300-archive/search.htm#querylangYahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Chrysler300/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/Chrysler300/join (Yahoo! ID required) <*> To change settings via email: Chrysler300-digest@xxxxxxxxxxxxxxx Chrysler300-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: Chrysler300-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/