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Automobile Engineering Lab Lab Experiments

Ovality and Taper Measurement of Cylinder Bore and Comparison with Standard Specifications


Checking the cylinder bore, measurement setting and rebore the worn out cylinder bore of an IC engine and set the tools and rebore the given cylinder

Tools Required:

Telescopic bore gauge, Vernier gauge, Micrometer, Test lamp, Machine clamping tool, bore clamp, telescopic gauge, Vernier calipers, feeler gauge, u- clamp and Allen key setting micrometer.

Cylinder Surface:

Normally in the IC engine cylinder wear at the top is maximum and impact scoring mark either thrust axis or crank pin axis to eliminate the scoring required by boring. The measurement of the cylinder wears, taper and orality by using telescopic gauge. These gauge and Vernier calipers can be used to measure the worn out bore. The cylinder ovality and taper should not exceed 0.050mm otherwise u.s.p and blow by will occur Bore dial gauge with setting ring is also used to measure the cylinder taper is high difficult for the rings to control by blow gases. The recondining that have excessive tapper or out of cylindricity is done by boring or reboring. Generally a cylinder greater than 0.006inches must be rebored and boring is done.


A cylinder that can not be cleaned by boring and it must be done by reboring process boring which rotates a cutting tool in the cylinder to remove the metals. These operation increase the cylinders bore diameter.


  1. Initially measure the cylinder bore size at 3 points like top, middle and bottom using telescopic bore gauge or vernier caliper.
  2. Set the cylinder bore centre and the font mounted spindle centre by using spring loaded pin arrangement.
  3. After ensuring the boring part is rotated at the exact centre of bore , tight the clamp giving more toque.
  4. Sides should be bored.
  5. Set the depth of stopper upto b.d.c.
  6. Rebore , then clean the ovality, taper , scoring marks e.t.c
  7. The vertical boring machine is placed on the engine, after it is fixed to the stand.
  8. Boring machine is fixed to the engine clamp and machine clamp.
  9. The spindle is lifted and to centered to the cylinder which is to be measured and machines using the pin and spring.
  10. The centering pins are introduced into their respective holes and the spring is introduced over them.
  11. The spindle is lowered into the bore and the centering pins are extended by turning the expander knob.
  12. Machine position is adjusted and the centre pins are extended and brought in such that the gap between the pins and the cylinders walls are same.
  13. After fixing the spindle is lifted and the centre pin spring are removed.
  14. The boring tool is now placed in the holder and the nut above the holder is adjusted using Allen key to move the boring tool. Its distance from the centre is measured by tool setting micrometer.
  15. Tool is set the required length according to the next specified bore diameter and tool adjusting nut.
  16. The tool position is fixed using the locker nut on one side, now the motor is started and the gear is engaged for automatic movement of spindle.


The IC engine cylinder reboring machine setting and machined to exact size of cylinder bore and tolls are set and cylinder of the given engine is rebored to the next standard size.