Is the combo top secret or something ??, why so vauge ??, do you want help ??, did you find the information already ??... Maybe if you give more us some more information, maybe someone can give an educated, knowledgeable or qualified answer, I/they would just be guessing otherwise, I'm not an expert either, just trying to help you... There's a great book "How to build Max Performance Hemi Engines" by CarTech books, writen/author by a FBBO member here Richard Nedbal owner of FastManEFI & a machine shop, maybe you could ask/call/contact him... SSR the coldest plug I used on a smaller 540ci Milidon Mastadon Hemi Blown/12.71:1 Mert Littlefield w/teflon strips & 20%-30% overdriven, w/Enderle Bug Catcher FI Hat & down nozzels, w/180A mech. Enderle Pump, appr. 10:1 semi flat-tops Venolia custom pistons, Childs & Albert Zero Gap Top rings, w/0.050"-0.070" thick Hussie dead soft copper head gaskets, 170cc Combustion Chamber, 0-ringed block, CNC ported Aluminum heads #P4876355 w/2.25" int./1.94" ext. valves & custom blower grind from Crane Cams 0.750" 292* roller & Vertex Magnito @ 36* locked down, CRC Methonal fuel... coldest c57 Champion or NGK equivalent 5672a-10 {I think}, hottest c63 Champion or KGK equivalent 5672a-8 {I think}, mostly depending on what altitude {higher hotter plug} & what thickness of head gasket & how much overdrive {more the colder the plug}, what nozzels or how good the track was prepped...but I highly doubt that will help with your combo... it may not even be in the correct range or style of plug for your specific engine...
