Rocker shaft lubrication

Started by Thomas, August 28, 2022, 10:02:39 AM

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While fiddling around with the inlet valve guide I wondered about the lubrication of the inlet rocker shaft. The rocker box is lubricated via the three small jets in its cover. The exhaust rocker shaft is lubricated by a hole on its tip and then through a hole under the felt ring. However, the inlet shaft doesn't show a respective lubrication hole on its tip (is it hollow at all?). I dismantled the Thackeray washer and found a small groove in the bush (attached). I also noticed a well lubricated outer shaft end so that I have good reason to believe that the groove lubricates the entire shaft and the felt ring. The small holes below both shafts are, hence, oil drains. My assumption is supported by grooves in all timing case bushes (attached). I wonder why the works did not choose identical lubrication techniques for both rocker shafts.

Cheers, Thomas
1946 BSA C11
1937 Sunbeam Model 9
... and a scratched Hyundai
(MSCR member)