Ariel Owners Motorcycle Club

Today I decided to sort through some spare parts I had, in a large biscuit tin, on a shelf; in the garage. Just setting the scene.
Amongst the parts, were four rockers and two shafts, which I purchased as part of a job lot, some time ago.
It was whilst I was trying the 'fit' of the rockers onto the shafts; to see if they were going into spares box or the junk pile; that I noticed that although they looked very similar; two of them were very wrong.
The oil exit hole, was drilled vertically. Thus most of the oil being fed into the shaft would immediately leave, via the incorrectly drilled hole.
I stuck some wire down the holes to demonstrate the angle. In the picture; left rocker bad; right rocker good.
These must be old, after market parts; and there may be many more out there; over oiling the rocker box, yet at the same time increasing the rate of wear of the shaft and rockers. On the plus side the cam shaft will get lots of lube.
Be aware; if you run your engine with the rocker covers off, and see an oil fountain shooting up towards the petrol tank, you may have one, or more, of these fitted.
The giveaway is that the good rocker has the part number ET/1306 cast onto it. The bad rocker has nothing. Cheers, Chris.

I seriously doubt that it matters much. It would be splashing off the cover and there's plenty of oil if it's spraying. Nev

My thinking Nev, is that being a plain bearing; no balls or rollers, it needs some pressure to build up in order to lubricate it properly.
There is also perhaps, the detrimental effect of pressure loss in the whole system; which could be important if due to a generally worn engine, your big ends are only just getting enough.

The stud in the crank case that the rocker feed and oil pressure gauge feed come from has a special
restriction precisely to stop the ends and mains being starved of oil because of excessive feed.

As the load on the shaft is not continuous the oil makes its way round quite effectively without any
breat pressure and the shaft is lubricated better with a reasonable amount of clearence - dead
tight and the oil goes nowhere.

will_curry wrote: Sun Aug 10, 2025 8:30 pm The stud in the crank case that the rocker feed and oil pressure gauge feed come from has a special
restriction precisely to stop the ends and mains being starved of oil because of excessive feed.

Do you have any details of that restriction?

As far as I remember the stud is 5178-37 and the oil passages - drillings - are specially sized, that is small.

I know my Mk1 has one fitted which came from the Healey brothers many years ago it being them that
warned me to be sure I'd go the correct stud. Right now I'm not able to strip the stud out to measure
but I'm fairly sure there is spare in one of the many boxes I've accumulated. Of course it might just be
the one I took out . . .

Mine came from Drags. If I recall correctly the holes are perhaps 1/16" or so?

Rockers don't require THAT much oiling. A drop a minute would be plenty. How much does the camshaft need oil from there? Nev

It's interesting to compare the cam oiling arrangements on two of my engines .

The square four camshaft is lubricated by splash from the big ends and oil falling from the tappets.

The FH however has a camshaft which sits in a cast channel in the crankcase which allows the cams to dip into an oil bath every time they turn - and they are also lubricated by oil falling from the tappets.

The FH, like its A10 ancestor, also floods the cam trough with oil from the
pressure relief valve. This gives the cam lobes a good bath on start-up
when cold.