PDA

View Full Version : What spark plug heat range do you run?



jwright
04-28-2003, 09:59 AM
I am curious what heat range spark plug people are using. I have a 350 (280 TRS package 1976). the book calls for AC-MR43T but they do not seem to have enough color after I pull them. I do have Mallory electronic ignition and a holley 650 but I doubt that makes a difference. Any opinions out there?
Thanks in advance!

Sam
04-29-2003, 08:26 PM
I found out I have a 5 heat range but I don't really understand what it all means.

Sam

MOP
04-30-2003, 05:52 PM
My opinion on plugs is if the engine has no major mods run what the book calls for. If it been worked over then I usually try a bit colder as a starting point. All you are looking for is clean burn and good color, hotter plugs than necessary can cause problems, hot plugs being longer in length don't dissipate heat as quickly as a shorter cold plug. In marine applications I lean toward a pretty dark brown and still a clean look to them. In cars a nice tan is fine, the engine loads are very different between the two.