29/05/17. Valve Rocker Shaft


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The rocker shaft assembly 

When I dismantled the engine, (all those years ago) I threaded the rocker shaft components onto a piece of string and tied them together in the same order that they’d come off the engine. Ideally you should also label the push rods so that you can replace each one in the same position it was removed from. Unfortunately, one of my original pushrods was bent and damaged, so I had to source some new ones. The idea for putting components back in exactly the same position as they were removed from is to allow that any specific wear to that component will match up with any wear to other parts.

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I started by pushing the rocker shaft back into the hole in the side of the cylinder head, and then once enough was through, I could put on the first spacer. IMG_6382 (Medium)

It’s also a good opportunity to lower the push rods down into the crankcase and make sure they locate on the followers at this point. This is easier said than done. I had to shine a torch down into the crankcase whilst trying to locate the pushrod, whilst at the same time trying not to drop it!

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One rocker located onto the pushrod

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The completed rocker assembly

Once all the components are in place, there are two bolts that secure the rocker shaft. These bolts locate into recesses in the rocker shaft and stop the whole thing spinning around. In my case, I had to adjust the shaft so the recesses were uppermost and in line with the bolt holes.

The next job is to adjust the valve clearances using a set of feeler gauges, a screwdriver and a spanner. I turned the flywheel so that the pushrod was not acting on the rocker. Then you can loosen the nut on the rocker arm, and with the feeler gauge between the rocker arm and valve cap, turn the screw to just bear onto the pushrod. Whilst holding the screw steady with the screwdriver, the nut can then be tightened to give the correct gap (around 0.030″ or 30 thou of an inch)

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With that job done, the rocker and hopper covers could be fitted and the engine takes a step closer to completion!

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