Jaguar 4.2 Build: The Bottom Part I

Having repaired the Jaguar 4.2 block with the Lock-N-Stitch process, assembly could begin from the bottom up. The first step was to hone the cylinders and ensure a smooth surface for the piston rings. With some oil applied to the abrasive stones each cylinder got around 20 to 30 strokes.

This engine shows signs it has been apart before. Aside from the factory labels of JVC1 through JVC7, several other marks were on the block. Typical of airplane construction, JVC1 was closest to the firewall.

The first step was to fit a rope seal which needs to be evenly pressed into place. These two-peice seals create a tight fit because the inner surface of the seal is rubber which expands when exposed to oil. Installation was done with a unique tool with a tapered surface that expanded the seal into place. A fitting on the end of the tool let us rotate the tool to avoid any binding.

Next the bearing clearances were tested with the main bearing caps fully torqued. After establishing good clearance (.002 shown), the 75 lbs crankshaft could be permanently installed with new bearings and thrust washers. Not long afterward the end play of the crankshaft was measured using a dial gauge which was magnetically fastened to the block. Typical play is .002 to .003 to a maximum of .005. If the end play was too much, oversize thrust washers would be needed.

Finally, distributor drive spindle was fitted using a modified distributor. This ensured that the torque wasn’t applied to the gears and instead the linkage of the distributor.

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