The Once-Popular Auto Tool No One Really Uses Anymore

In the past, car parts used to be rather finicky. You had to occasionally adjust the carburetor to ensure your car was getting the right amount of fuel. You had to check the coolant every season to make sure you weren't overheating in the summer and freezing in the winter. You also had to make sure the spark plugs had the right gap between the electrode and the ground to get a proper spark. You had to get out the calipers, gauges, and gap tool to get everything just perfect. 

I've worked on all manner of spark plug arrangements, from messing with the plugs on my dad's lawnmower, my own Chrysler LeBaron, and a friend's AMC Hornet, to modern coil pack setups on a number of cars from this century and a spark plug gap tool has come in handy. But can you even remember the last time you used a spark plug gap tool, if ever? The advent of fuel injection and more advanced engine cooling systems did away with carburetors and needing to get worried about coolant levels in a modern car. Spark plugs and the lack of need for a gap tool, however, are a little less obvious of an advancement. 

Spark plug gap tools still exist, of course, and there's a good chance the local auto parts store near you has one in stock ready to go. It's not entirely irrelevant because if you modify your engine to any extent, you'll need to keep a spark plug gap tool around. Since over the course of modification, you may be messing with the fuel/air/spark mixture and therefore find it necessary to go a little more in depth to find the optimal spark for your individual needs. It's not a hard and fast rule that you need one, but it doesn't hurt to have it around. Additionally, it might come in handy if you spend any time working on lawnmowers and other small engines.

Modern spark plugs in a car mostly stock, however, don't really need all that much adjustment. Your average plug comes with the optimal gap already from the factory. Niterra, the company that used to be called NGK, a well known name in spark plugs, notes that most individual spark plugs are compatible with hundreds of different engines right out of the box. This negates the real need to use a gap tool every single time you mess with the plugs. The gap tool itself has gone from an absolute necessity in every automotive toolbox to residing in the back of the tool cabinet with that weird carburetor you forgot about and a half empty can of brake cleaner.