Brand: Automotive Racing Products (ARP)
Take the guesswork out of indexing plugs! This compact tool from ARP shows you exactly where the ground electrode will end up when you install each spark plug in your cylinder head.
Indexing plugs is critical with domed pistons in high-compression engines. Proper indexing can even help extract just a little more horsepower in any engine. Careful positioning of the electrode in the combustion chamber can help quick propogation of the flame front and can even encourage a more complete burn of the air-fuel mixture.
This anodized aluminum spark plug indexer has female 14 x 1.25mm threads to accept common tapered-seat spark plugs (including FF1600).
Even if you don't index your plugs, proofing each plug prior to installation is an excellent "insurance policy" against tearing the threads out of your aluminum cylinder head! Just thread your plugs into this tool to identify defective or damaged plug threads before they can do any damage.