Jabiru 3300 - Preparing Replacement Pistons for Refit

Introduction ...

This page contains photos of a Jabiru 3300A Solid Lifter engine under going a bulk strip and rebuild. This page documents the process of preparing a replacement set of pistons for refit.



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Image 1

Here are a fresh set of pistons. The previous set had such heavy carbon build up and it proved impossible to free up the piston rings in their landings. The new set of pistons comes with fres piston pins and piston pin circlips ...

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Our first job is to wiegh the pistons and arrange them in weighted horizontally opposed balanced pairs. For example the piston destined for cylinder 1 is matched weight wise with the piston destined for cylinder 2. The piston destined for cylinder 3 is matched weight wise with the piston destined for cylinder 4. The piston destined for cylinder 5 is matched weight wise with the piston destined for cylinder 6. In practice the tolerance of this set of six pistons was so good they all weighed the same to within the nearest single gram. But at least we went through the process of weighing and checking them! ...

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The next step is to install one pison pin circlip to each piston ...

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Placing the circlip on a flat clean surface ...

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Pick it up with the circlip pliers. Do not stretch / compress the circlip anymore than is necessary to position it in the circlip groove. Over compressing it will render it useless ...

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The curved face of the piston pin circip faces in towards the gudgeon pin / piston pin. The flat side of the piston pin circlip faces outward e.g. away from the load imposed upon it from the piston pin. It is very important to get this right ...

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Take great care to ensure that it is correctly seated all the way around it's circumference in the circlip groove ...

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Once you are satified that it is seated correctly carefully release the circlips pliers ...

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Next get a new set of piston rings ...

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Note the two compression rings on the left. The various components of the oil scavenging ring are on the right ...

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Oil the ring landings ...

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Start to fit the rings by postitioning the spacer ring ...

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Then the pair of scavenger rings followed by the compression rings ...

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Next supporting the piston on it's side (we rested it on a V-block) "start" the gudgeon pin in the piston ...

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This piston is now ready to be put back on it's parts tray in readiness for refitting to it's conrod ...

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