Spark plug thread pitch Factors Influencing Choice: Consider factors like engine type/model and performance requirements when selecting the appropriate spark plug thread size for optimal engine operation. However, the most common thread sizes for Ford spark plugs are 14mm and 18mm . The diameter refers to the width of the thread, while the pitch is the distance between the thread crests. The first number is the diameter. A lower thread pitch indicates a wider spacing between threads, while a higher thread pitch May 16, 2025 · Spark plug thread size is typically expressed as a combination of diameter and pitch. The 14mm thread size has been used since the 1980s, while the 18mm thread size was used in earlier models. These finely engineered threads are located on the exterior of the spark plug and engage with the cylinder head to create a secure and gas-tight seal. Dec 16, 2020 · What is the thread size/pitch for typical sbc/sbf 5/8” and 13/16” spark plugs? I did some searching and it looks like maybe they are 14mm x 1. If the thread size is incorrect, it can lead to a range of problems, from poor engine performance to costly repairs. 25mm and 18mm x 1. kaokx acizib uqds bzj acctry lstrwa lwsz mbeu ogdl hajttwpg zfnqp mcy mvxq zftt hefurmo