Check the listing for details. 8199 ACCEL HP Copper Spark Plug - Shorty. Condition: New, Made in CZ. Listed at 58.95 USD. 14mm Thread - .460 in Reach - Tapered Seat - 2 Pack of 0576S-4 (8 Spark Plugs). ACCEL's patented race proven spark plugs in a shorty configuration. The overall length has been reduced 3/16 in to 3/8 in (depending on the specific spark plug) to gain critical air gap between the spark plug boot and the exhaust manifold or header tube. This helps eliminate burning the spark plug boot or dimpling the header tube. The shorter spark plug length also can make it easier to install and remove the spark plugs in certain applications where there is not a lot of room to fit a socket or move a wrench around. ACCEL Shorty Spark Plugs are made with a copper core which is a better conductor than platinum and iridium. They deliver a stronger spark especially in high performance applications where high.