Jabiru 3300 - Reassembly - Re-fitting The Cylinder Heads

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 re-fitting the cylinder heads.



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Image 1

Start by removing the old pushrod o-rings and replacing with new ...

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Here we have a cylinder head with valves lapped in and refitted together with valve springs, washers and cotters etc. We seem to have omitted to take photos of the cylinder head rebuild so they will have to added in the future. To facilitate refitting the cylinder head it is easier if the valve springs are compressed even though in the case of this one we have already fitted rocker arms and shaft etc. We have our own self fabricated version of the valve spring compression tool as described in the overhaul manual ...

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It comprises of a thick bar that has two bolts that secure it to the cylinder head - see arrows ...

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And there are also two bolts that are then screwed in to compress the valve springs (by displacing the top valve spring washer) which in turn relieves pressure off the rocker arms and in turn the pushrods ...

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Spray a little ACF30 (rubber friendly) on the pushrod tube o-rings in both the crankcase and the cylinder head. This will make it easier for the pushrod tubes to locate into their correct positions ...

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Insert the pushrod tubes into the crankcase and then insert the pushrods themselves. For a solid lifter engine like this one the end of the pushrod locates in the "cup" at the end of the solid lifter. It is easy just to push the pushrod down the pushrod tube. Ensuring that the end of the pushrod locates correctly in the solid lifter cup can take a bit of "feel". A generous blob of MolySlip on the end of the pushrod will help to ensure that once the pushrod is located in the cup it will more than likely stay there during the process of persuading all the cylinder heads into their correct positions. Note that it is only safe to use MolySlip on a solid pushrod. Note that we have started here on cylinder 6. We could have started on the other side of the engine at cylinder 5. Either will do provided that you start at the flywheel end of the engine and work your way down the cylinders towards the PTO end / propeller flange end of the engine ...

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Apply a generous blob of MolySlip to the end of the pushrod, as shown here, before inserting the pushrod into the pushrod tube ...

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Before offering the cylinder head to the barrel ensure that piston for the current cylinder is at TDC. Note that plenty of high temperature lubricant is applied to the cylinder barrel threads and also the cylinder head bolt threads ...

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Ease the cylinder head into position taking care to guide the end of the pushrods into the adjustable "cups" of the rocker arms ...

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Gently torque up the cylinder head bolts evenly ensuring that the cylinder head seats correctly and that the ends of the pushrods do not come out of the adjustment cups whilst you are doing so ...

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Next it is time to re-fit the valve train oil feed tube ...

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Now is a good time to clean up the oil feed tube and replace the o-ring ...

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Having replaced the o-ring and removed any flakey paint and FOD we can push it back into the crankshaft. Again a little ACF50 on the o-ring helps protect the o-ring during insertion and helps it ease into place ...

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We can now secure one side of the rubber T-connector to the cylinder head we have just re-fit. The cylinder heads are only loosely torque'd up at this point because to get the other end of the rubber T-connector onto the next cylinder head's lube tube on this side of the engine it helps if there is some flexibility of movement ...

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Carry on working down the same side of the engine fitting the rest of the cylinder heads. Note pushrods inserted with a blob of MolySlip at either end and piston is at TDC ...

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Once all cylinder heads and the T-connectors on the one side of the engine are in postion and seated properly you can torque up all the cylinder head bolts on that side of the engine in a progressive pattern ...

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Go back to all the oil feed tubes and check connections for tightness ...

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Finally refit the oil feed tubes retaining bolts and specially machined retaining washer. Next re-fit all the cylinder heads on the other side of the engine ...

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