Total Seal: Tool Tips For Piston Rings

The Process

Attention to details while assembling your new engine is what will make the difference in its performance and endurance. There is a long list of measurements, specifications and details to check and double check throughout the process and one of the most important specs to get right is the piston ring end gap.

Ring end gap is required to allow for the rings to expand as the engine warms to operating temperature. Too little gap may allow the ring ends to butt against each other which can push the ring through the thin film of oil on the cylinder wall and cause damage to the bore. Conversely, too much gap will result in a reduction of cylinder pressure, stealing potential power and even causeing excessive smoking and oil consumption.

Obtaining the correct ring end gap may seem daunting at first, but by taking your time and checking your work, the right gap can easily be achieved. Total Seal offers all of their ring series as file-to-fit designs so there is always a little extra material to be removed to cover different applications. Filing the rings is a simple process and can be handled in several different manners. We’ll start with the most basic; a file and a vise.

Tool #1 – Gap (ring in the cylinder)
To measure the ring end gap, the ring must be placed square in the finished cylinder bore. Measure the gap with a set of feeler gauges.

Tool #2 – File
If you only build one engine here and there, the classic hand file will do just fine. Always put the file in a vise and work one side of the ring gap only. Remember, it only takes a few laps on the file so be sure to take a little, then measure again.

Before you start filing, you must first know the ring gap specification for your engine. Total Seal has recommendations for each ring set, and if you have any questions, it is best to contact their tech line so they can walk through your specific application and provide the best gap dimension. To check the gap, the cylinder bore must be finished including the hone. Place the ring in the cylinder and square it up with a ring squaring tool, or a piston. Position it about an inch into the bore and check the gap with a feeler gauge.
Back to filing. With the file firmly held in a vise, file one side – always only one side – a couple times. Try to hold the ring square against the file for an even cut. It doesn’t take much so be sure to file then measure a couple times. (Total Seal offers all of their rings separately just in case you over-file one.)

Tool #3 – Hand Crank
The next step in ring gapping tools is a hand crank tool. This tool improves the consistency of the filing and speeds up the process. (You can even modify it to accept a drill motor!)

The hand file works well if you build one engine every couple years, but if you’re doing a several engines a year, there are two options to consider; a hand crank grinder or an electric powered grinder. The hand crank tool also clamps into a vise but provides the ability for more precise cut on the ring and will help quicken the process. You still need to cut – measure – and cut again for accuracy though.

Tool #4 – Power
The most accurate ring grinding tool is Total Seal’s Precision Power Ring Filer. This machine allows you to take off a select amount while keeping the ring square for the best gapping process.

For engine builders that want absolute accuracy and repeatability, Total Seal’s Precision Power Ring Filer is the way to go. This tool was designed by Total Seal and is hand assembled at their facility in Phoenix, Arizona. The Grinder allows you to square the end of the ring and lock it in place on the grinder. Also, you can adjust the amount of material to remove so you don’t need to worry about over-filing. Not only does the machine produce a precise, accurate cut, but it speeds up the process as well!

You don’t have to be a professional engine builder to get pro-like results in your build. It all comes down to taking your time and double checking your work and specifications. When it comes to ring end gap, Total Seal has the tools, and the knowledge to help you get the right rings and the right fit.


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Total Seal





(800) 874-2753


22642 North 15th Avenue

Phoenix, Arizona 85027

ABOUT Total Seal®

In late 1999 we moved into our new 32,000 square foot facility in Phoenix, Arizona. It houses the latest in research and development equipment, manufacturing machinery and technology focusing on developing and manufacturing piston rings for any and all applications.Our rings continue to show up on the world's fastest, from NASCAR to IMCA to IndyCar, from marine to drag racing, oval track to off road - nobody builds piston rings that seal better than Total Seal.