Valve Seat Cutters
About Neway Cutters
Neway makes many different kinds of valve seat cutters for all sorts of engines. If you cannot find exactly what you need on our shelf, we can make a custom one for you. We have made tiny cutters for model airplanes and giant ones that can cut seats over six inches wide. Most likely, your engine will be somewhere in between.
Neway cutters are not built for just one type of engine. It does not matter if you are working on a high-performance car, an old motorcycle, or an airplane engine. If the cutter fits and has the right angle, it will work. Our special carbide blades can cut through almost any material, whether it is soft or extremely tough.
These cutters feature adjustable carbide blades. While the angle of the cut is fixed, the blades can move in or out, giving each tool an "operating range." The operating range tells you the smallest and largest valve size the cutter can handle.
[Image: Diagram showing a Valve Seat Cutter and its parts]
Finding the Right Cutter – The Simple Guide
Size: Measure your valve head. The cutter body (the yellow part) should be about the same size as your valve. Generally, the cutter can be 1/8" bigger or 1/4" smaller than the valve.
Angles: You need three angles for a good valve job: the main contact surface and two "narrowing angles" (one above and one below the contact surface). Most valves are 45 degrees. If you do not have the specific instructions for your engine, we recommend the standard 30° - 45° - 60° profile.
Pilots: Make sure you buy pilots that match your cutter. Small series cutters need small series pilots, and so on.
Case, Wrench, and Accessories: A good kit should have everything: the cutters, pilots, a case, a wrench, and any other tools you need.
Finding the Right Cutter – The Detailed Guide
Whether you are fixing one valve or working on a whole set of engines, the process is the same: find your valve size to choose the cutter diameter, then pick the right angles.
Cutter Operating Range
An "operating range" is simply the range of sizes that a tool can work on. We have to be careful because sometimes parts of the engine (like the cylinder head wall) might get in the way of the tool.
Usually, when the cutter body is 1-1/4" or larger, the blades can adjust to cut 1/4" larger than the body. For example, if your cutter body is 1-1/2", the blades can extend out to 1-3/4".
The "inner" range is trickier. It mostly depends on if the tool will physically fit into the space without hitting the walls of the engine. A good rule of thumb is that there is a 90% chance the cutter will work if the valve is 1/8" (3mm) smaller than the cutter body.
[Image: Chart showing the probability of a cutter fitting based on size differences]
The 3-Angle Valve Seat
If you are new to this, a "three-angle seat" just means creating a clean, professional seal. You need one main angle where the valve hits the seat, and two "narrowing angles" above and below it. These narrowing angles help control where and how well the valve sits.
[Image: Diagram of a 3-angle valve seat profile]
Methods of Turning the Cutter
There are three ways to turn your Neway cutters:
- T-Wrench: This is a simple handle, perfect for light work or when you want to be very careful. It is slow for big jobs.
- Easy-Turn Wrench: This turns continuously, which is faster because you don't have to stop and change your grip.
- Power Unit (PU-1800): This is an electric motor. It is the fastest way to work if you have many valves to do.
[Image: Photo of the different Wrench tools and Power Unit]
Choosing Your Series
Neway offers three series of tools:
- Standard Series: Used for most cars, motorcycles, and marine engines with valves from 1" to 2-3/4".
- Small Series: Used for smaller engines like lawnmowers or small motorcycles, with valve sizes from 5/8" to 1-5/8".
- Heavy Duty Series: Used for very large engines (3" to 6").
Need more help? Check your engine's manual, or contact us if you have questions about specific kits.