The Nuts and Bolts
Customers often say: "I'm installing new hardware and I can't seem to keep it from binding!"
We have all probably had threads gall or bind up on us, It's enough to make you want to pull your hair out! There are several reasons this happens, and it is the most common with chrome or stainless steel but can also occur with plain steel. To save yourself time and money, you should always run a thread chaser or tap and die over and through any threaded item before assembly, especially if it’s a chromed or stainless steel item. Then apply a thread anti-seize compound liberally to both threaded surfaces before attempting to put them together. All engine and car builders use this method to ensure a problem-free build.
Most of us take bolts and studs for granted. ‘A bolt is a bolt’ has been muttered many times by people putting together engines or cars. As you know, there are many grades of bolts and studs and they must be matched to the type of use they are going to see. That said, here are a few suggestions of what to look for and how to properly install and use engine fasteners.
The first time you tighten up a new bolt or nut is when it sees the most friction. There are sharp edges and manufacturing burrs that will cause problems unless they are dealt with. All new fasteners should be torqued and loosened several times before final assembly. The type of thread lubricant will make a big difference here. If you use ARP’s thread lubricant on their fasteners, you should torque and loosen five times before final assembly.
As stated above, the type of thread lubricant used will make a big difference in final torque accuracy. If you just use motor oil, there can be a 20% - 30% difference in final torque compared to ARP’s lubricant. The motor oil will normally require a higher torque figure due to the increased friction of the threads. Use what the bolt manufacturer recommend.
The finish of the bolt also makes a significant difference in torque numbers. Many engine builders remove the black oxide finish most bolts and studs come with to get a more consistent torque after the engine has been run in.
- Be sure that your torque wrench is checked for accuracy at least once a year. You can send it in or find a tool dealer to have it checked.
- If you have just had your block machined, you will need to run a tap through every hole to make sure the threads are free of dirt and debris.
- Always remember to use a thread sealant on bolts that go into water jackets. If this is not done, odds are that water will wick its way up the fastener and you will end up with a leak.