When you get ready to assemble an engine or it’s components, cleanliness is one of the most important things. Trash on surfaces can cause issues with how bearings sit, can send stuff through the oil, and more. But one of the places people often overlook are bolt holes. And it doesn’t matter if your engine is used, new, or fresh from the machine shop, you need to check all the threaded holes and make sure they are clean. Unfortunately, spraying brake clean into the holes and then blowing them out with air isn’t enough. You need to run a thread chaser into or through each and every bolt hole. And the right tool matters.
Some folks skip chasing threads because they aren’t comfortable running a tap through them for fear of messing up the threads. And with good reason! This is NOT the right tool. A thread chaser is a tool specifically designed to run through the threads but without any cutting action. The flutes on the sides of them are there to remove any dirt and foreign material within the holes, but without causing any damage to the threads themselves and you can buy them at lots of tool stores. Not all thread chasers are the same however.
Higher quality tools, like those from ARP, have much more precise tolerances so they are much more effective at cleaning the threads. They also have much deeper threads than many of the others that are available and that cleans a lot more effectively. You need the threads to be clean so that you get accurate torque, stretch, or yield measurements when assembling engines. If there is dirt in those threads that keep your rod bolt from being tightened properly, it’s going to cause serious engine failure. And the same can be said for any critical fastener in your engine.
Do it. Clean them. Use the right tools.
Here’s all the info from ARP. They’ve got them in all the sizes.
Properly preparing engine blocks, cylinder heads and
other components for assembly should include thoroughly
cleaning all threaded apertures. Debris can severely
compromise accurately preloading a fastener, which is why
ARP offers specially designed “chaser” taps. They are not
designed to cut threads; only clean them.
ARP has expanded its tap offerings to include some
22 different sizes (SAE and metric), plus combination sets
that feature the most popular sizes.
Along with using “chaser” taps, engine builders can
rely on ARP Ultra-Torque® fastener lubricant to obtain
accurate fastener preloading. Extensive laboratory tests
show it to be far superior to oil, moly, EPL and other
substances in delivering 95-100% of the desired preload in
the first (and any subsequent) “pull” of the torque wrench.
For additional information visit www.ARP-bolts.
com. A printed copy of the new 2024 catalog (which shows
all tap sizes) is available upon request. Personalized tech
help is available by calling 800-826-3045.
