| Don't know about the MSD box with a mod motor, but I do know that there is a lot more involved when making an evaluation of this kind. Yes, you can look at a specific component but you must also look at the issue from a systemic view. That is: look at all the components in the system.
Getting the proper heat range plug is important. You're most likely to experience a problem with the plug before you melt down your piston (at least that's been my experience). Getting the proper heat range plug is a bit more difficult than it sounds. You need to consider the cam you are running, most specifically, the cam duration.
If all things are equal, a longer duration cam produces less cylinder pressure (something akin to lowering compression ratio). A longer duration cam is designed to make more horsepower at higher engine speeds. In this example, a hotter plug would be a better choice. I would assume that more spark would also perform the same task.
Given that is the case, the opposite would be true is you were running a short duration cam. Short duration cams tend to smooth out the idle and give you some low speed torque. A colder plug is more appropriate for that application, and again I assume that less spark would be applicable.
Given the type of car we are talking about here, I also assume that low speed torque is not really what you are after. So you probably have a longer duration cam. A hotter plug or more spark would probably be called for.
Anyone see any errors in my thinking?  |