Valve guide oil hole.

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Dec 2, 2012
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My friend has a 650 twin an it has small oil feed holes in the head an through the valve guide to oil the valve stem. I have never seen this done before even on older engines than this one.
As it now runs modern oil not fifties type oil is this needed or can it be carefully peened closed without harming the valve to gude ware. It has new valves an new original type iron guides a has had full rebore crank regrind type rebuild so all is as good as new but this oil feed seems a solution to a none existent problem.
 
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The AMC twins had a sophisticated and expensive oiling system. Like modern engines and unlike the Norton Atlas engine, all oil lines are concealed as drilled oilways, even to the cylinder head. Most of these drillings are metered to ensure the crankshaft center bearing journal and the conrod journals receive correct oil pressure.
I wasn't aware the valve guides are lubricated from such drillings also and I will check. However, there are drillings to each rocker arm post and from there to the rocker arm bearings. On later engines there is an outlet at each rocker arm which is channeled to the pushrod cup, and further downwards to the pushrod ball and camshaft follower. This ensures positive lubrication of the entire valve gear.

The short answer is: No, you can't peene the oilways as this will ruin the rockers and valve gear of lubrication. Cylinder heads will also overheat.
If your friend's engine is suffering from overoiling the valve stems, he may consider fitting valve guides with less or no oiling holes (do this at his own risk). Are meter jets in place?

I would not run a 50's engine on modern synthetic multigrade oils. Investigations have shown that oil pressure may drop to almost zero under certain circumstances. Keep to the factory recommendations! Overoiling may be the result of using lube oil of too low viscosity not providing sufficient restriction in the meter jets).
Fit an oil pressure gauge for calibration of oil pressure. Keeping the built-in oil filter clean is extremely important for these engines (there is no centrifugal "filter" like on the Norton). Fitting an external 10 micron cartridge filter is probably a good idea.

-Knut
 
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These are not the rocker feed holes they are all as they should be including the brass plugs that are drill to meter the head oil feed.
These are drilled through the head an through the valve guide to oil the valve stem. It is mentioned in the manual an he has a second set of heads with the same holes in the same place.
It has a spin-off oil filter fitted to the return pipe of the oil tank.
He is using a "classic" straight 50 oil not synthetic my comment about the use of modern oil was that on the whole they are better an that which would have been used in the day. An this machine get more care an money than the ones he rode back in the day as his only all weather all purpose transport.
 

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