How to hone a cylinder wall

Written by dan ferrell
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How to hone a cylinder wall
Stones of different grit can be used with honing tools like these. (Photo courtesy of Pudding4brains at

If you are restoring the engine block on your car, it is necessary to hone the cylinder walls to get rid of the glassy coating, or after boring for proper piston-ring operation. The process is simple, and you can do it in your own garage if you follow the correct procedure.

Skill level:
Moderately Easy

Things you need

  • Drill
  • Cylinder hone
  • Goggles
  • Motor oil
  • Kerosene
  • File
  • Soap
  • Cloth
  • Anti-rust protective oil

Show MoreHide


  1. 1

    Set the engine block on an engine stand if you have not done so already. You can use the top of a sturdy workbench instead; just make sure the engine block is set firmly on the surface.

  2. 2

    Set the honing tool in a large drill with a slow speed setting. You may use a brush hone if the condition of the cylinder walls is fairly good and they just need deglazing. Use a flex (stone) hone if the cylinder is worn but not excessively; use a rigid (stone) hone if the cylinders are excessively worn but still within manufacturer specifications. Also, if you are installing cast-iron or chrome-faced rings, use a 280-grit stone; for moly rings, use a 400-grit stone.

  3. 3

    Mix equal amounts of 20-weight. motor oil and kerosene in a clean plastic container and use the mixture to lubricate the cylinder walls. Put on your safety goggles. Hand-squeeze the brush or stone hone and slip it into the cylinder.

  4. 4

    Turn on the drill and keep the hone moving up and down the cylinder wall at all times, at a pace slow enough to produce a crosshatch pattern of about 50 to 60 degrees on the wall. Keep the cylinder wall well-lubricated. When you are finished, shut off the drill, but keep the hone moving until the drill stops. Compress the brush or stones and pull the hone out of the cylinder. Continue with the next cylinder until you are finished.

  5. 5

    Chamfer the top edge of the cylinder walls with a small file so the pistons will not seize during installation. Thoroughly wash the engine block with soap and warm water, to get rid of the grit produced during honing. Dampen a white cloth with new motor oil and wipe the cylinder walls. If the cloth picks up grey residue from the wall, wash the engine block again.

  6. 6

    Rinse the engine block and cylinders with clean water. Dry the engine and lubricate the cylinders with anti-rust protective oil. Cover the engine with a plastic bag to keep dust off.

Tips and warnings

  • If you do not know if the cylinders are within manufacturer specifications, take the engine block to an auto machine shop for inspection. If the cylinders are excessively worn, the machine shop may bore the engine for you, or install a new cylinder skirt if necessary. They will tell you what size piston and ring size you will need for the engine.
  • If you do not own a honing tool, you may rent one at an auto-parts store.

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