Then, it's transferred to the coolant passages. Look for signs of the ditch beginning to be filled 14mm HOT 3/4" Reach RFN14LY 82 5/8" Hex RCN12LYC 412 Extended Gap COLD 14mm .884" Rch. E3 does not have a standardized heat range identifier. This is called “thermal performance,” and is determined by the heat range selected. (Color= meaning the evidence of heat/or lack of heat by the appearance 9. to the base ring (last thread ring), then it means that the plug heat-range power, to the ground strap's end, (which is above the center electrode), then **TO SUBMIT AN ARTICLE TO ENGINE BASICS PLEASE CLICK: CONTACT US! A very expensive heat range test can be performed however a more viable option is to start with a colder heat range spark plug and perform some testing. . Here we go again. Those w/ SC or 3.2Carrera engines and an MSD CDI: What plug gaps are you running and w/ what heat range plugs for street cars? By as specks are soot that was clinging to clearance volume surfaces in the Where is E3? However, according to an Autolite reference chart, Autolite 86 has the same heat range as 2244 and Autolite 303 is a hotter plug than 2974.