What is the purpose of spark plug heat range, and what problems can arise from using an incorrect heat range plug?

• A. Heat range determines how many electrodes the plug has.
• B. Heat range determines how quickly the spark plug dissipates heat; too hot can cause pre-ignition or overheating, too cold can cause fouling and deposits, leading to misfires or poor performance.
• C. Heat range determines thread size in the cylinder head.
• D. Heat range affects only cold-start duration.

Answer: (B)