Precision Engine Machine's new Lock-In Tools promise to make installing piston pin locks-long one of the most detested jobs in engine building-a much easier task.
For engine builders, the racing world is filled with fantastic components that are designed to produce maximum power without sacrificing durability. But that doesn't mean that everything is always fun and filled with sunshine.
Take, for example, floating wristpins for racing pistons. In stock engines, the wristpins are pressed into the small end of the rod and allowed to float in the piston's pin towers. The press-fit into the rod keeps the pin from sliding out of position and scrubbing the cylinder wall, but in high-performance applications it also creates a greater possibility for the pin to gall against the pin bore in the aluminum piston. This problem is solved in racing pistons by using wire locks that fit into grooves in the pin bores. These locks locate on either side of the pin so it cannot slide far enough over to scrub the cylinder wall, but they do not keep the pin from rotating like a press-fit in the connecting rod does. By installing a bronze bushing into the pin end of the connecting rod and allowing the pin to float freely in both the rod and piston pin bores, you can significantly reduce the chances of galling the wristpin with only minimal splash oiling.
The Lock-In-Tool for spiral locks uses a groove cut into the body of the tool. Inventor Clyde Norwood says there is a precise angle this groove must be cut on or else the tool will not work.
The problem, however, is that while racing technology can make components that produce fantastic power with good durability, ease of installation is rarely a design factor. Even experienced engine builders will tell you that installing pin locks in the pistons can be one of the most annoying jobs in the assembly process.
There are two basic types of pin locks: a spiral lock, which is basically a flat wire wound into a spiral, a lot like a small slinky, and a wire lock, which is round wire formed into a semi-circle slightly larger than the I.D. of the groove in the pin bore. Typically, installing either usually requires a small screwdriver and a surgeon's touch. And if it isn't done right you can easily leave plenty of scratches from the screwdriver on the side of the piston which can cause stress risers. Broken and bent wire locks also aren't unusual for new engine builders.
Each Lock-In-Tool includes this retaining clip. For demonstration purposes, it has been painted red to make it show up more clearly. Its purpose is to keep the pin from sliding out the back side of the piston's pin bore while you are attaching a lock.
That's why when inventor Clyde Norwood demonstrated how to use his new Lock-In-Tool, we were left slapping our heads with the old, "Why didn't I think of that?" Norwood is a longtime race engine builder and the owner of Precision Engine Service in Waxhaw, NC, and admits to having been aggravated for years by the task of installing piston pins on connecting rods. But instead of griping about it, Norwood put his mind to developing a better mousetrap and came up with his Lock-In-Tool, which is a dead-simple way of painlessly installing piston pin locks. Also, his new tool virtually eliminates the chances of scratching up the piston or breaking a wire lock in the process.
Norwood's Lock-In-Tools are cut from billet steel and have a nice heft that not only has the feel of quality but also helps seat the locks properly. There are different tool designs for installing spiral locks and round wire locks. Also, different pin diameters will require different tools, but Norwood is producing tools for almost all popular pin diameters used in racing. Follow along as we put the Lock-In-Tool to the test.
Installing Spiral Locks
Simply squeeze the clip and insert the ends into the lock grooves in one side of the piston. This keeps the pin from sliding out without damaging the groove. | 
Now you can install the rod in position and slide the wristpin in place. | 
Using your fingers, open the spiral lock enough to begin threading it into the groove on the tool. |
Continue to thread the lock onto the tool until the end is close to the registration mark. | 
Insert the tool into the piston pin bore with it tilted slightly so that the side with the registration mark is lowest. Once you feel the end of the lock is in the groove, straighten out the tool and press down against the wristpin. Begin turning the tool counterclockwise to unspool the lock into the groove. | 
When the wire lock is fully seated in the groove and off the Lock-In-Tool, you will hear a small pop. Double check to make sure the lock is fully seated in the groove and repeat the process on the other side. |
Installing Round Wire Locks
The tool for round wire locks is much simpler. Instead of a groove cut into the body of the tool, it uses a die to help press the round wire in place. | 
Begin by placing the retainer clip in the back side of the piston, as before, and installing your rod and wristpin. In this photo, the wire lock has been painted red to make it easier to see. Position the lock so that one end is in the groove. All you have to do is place it there; you do not have to force anything. | 
Now, press the Lock-In-Tool in place on the same angle as the wire lock. |
Begin working the tool around as you press down, beginning with the end that is already in the groove. Slowly work the wire lock into the groove. By pushing down on the handle and pivoting it, you should be able to work the lock completely into the groove. | 
Again, you should be able to feel when the lock pops fully into place. Check to make sure it is seated, pull the retainer clip from the opposite side of the piston and install the lock on that side to complete assembly of that rod and piston. | |