Well this may sounds like a stupid question but i hope someone here can anwser it for me. What does it mean when some one talks about a "Hotter" or "Colder" spark plug? and how do they affect the proformance?
thanks
-Doug

 

High Doug, the heat range of a spark plug is determined by the length of the ceramic insulator that surrounds the center electrode. The longer the insulator is the hotter the tip of the plug runs due to a longer path to shed the heat of combustion. If the engine is close to stock and in decent shape (not burning oil) then the factory heat range plug should do a good job. In general terms, a low performance, low compression engine will be fitted with a hotter plug because the combustion temperature is low and wont burn off combustion deposits as easily. On the other end of the scale will be a colder plug, if the engine has a high compression ratio which translates into hotter combustion temperatures then you'll want a colder plug, this will reduce the temp. of the tip of the plug that could become a hot spot, it reduces the chance of pre-ignition or "ping". So the trick is to find the correct heat range for the application, you want a plug that is hot enough to burn off the deposits but not so hot as to cause pre-ignition. I start with something close to the original then read the plugs and go from there. You wont be able to feel a performance difference between the different plugs unless the plugs your taking out have been misfiring. Hope this helps, we can continue this thread with more detail if needed. Bob

 

Thanks Bob I was just curious about the teminology. I just have a stck L48 motor and i have stock Acdelco plugs i was just cuious

 

I also have the L48 which I believe is still stock inside. I'm in the process of putting together a 383 right now with a slightly higher compression ratio than the L48 and the L82. I'll end up with a C.R. of 9.25 - 9.50 and I'll start out with a plug two steps colder than the L48. After I run the engine awhile under normal driving I'll pull the plugs and see how their burning and adjust heat range from there.