6/25/2010
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Three-Angle Valve Seat Cutting Tips
Goodson Tools offers tips for engine builders doing three angle valve jobs with carbide pilots.
1) Use new carbide pilots for precise and high-quality valve seat and bowl work.
• Carbide pilots help keep tooling cutting true. When cutting 3-angle seats,
counterboring for seat rings or using bowl hogs to enlarge valve bowls,
the resistance of the workpiece against the tool tries to deflect the
pilot. Goodson Carbide Pilots resist this deflection five times better
to keep the tool cutting precisely in its path.
• Carbide pilots are resistant to wear and maintain "like new" precision. Carbide pilots are much more resistant to wear than tool steel pilots. As steel
pilots wear, they lose their initial precision and allow an increase in
run-out with age. Carbide pilots maintain their greater precision many
times longer. Their stability in use and performance over a long period
of time makes these pilots a greatly superior tool.
• Creates
the most concentric valve seat finish. The rigidity of the carbide
pilot (5 times less deflection) creates the concentric valve seat
finish available. Please note, however, that due to the brittle nature
of carbide, they must be handled with care!
Goodson's
carbide pilots have .375" top-size and range from .157" (3.99mm) to
.379" (9.626mm). Goodson has Serdi-style straight (live) or
conventionally tapered (dead) pilots available.
2) Be sure to secure cylinder head. Some shimming may be required to assure a more concentric seat and a
better finish. Make certain that the cylinder head is firmly attached
to the head fixture of the machine so that no vibrations can occur.
3) Keep tips sharp! Remember that the tip (or formtool) should be kept sharp at all times.
DO NOT allow it to become dull. The sharper the tip, the less drag it
will have, thus reducing the chance for chattering.
–Tech Tip courtesy of Goodson Tools & Supplies