rocker lubrication

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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Chris Berry
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Joined: Fri Sep 16, 2016 7:51 am
Location: QUEENSLAND AUSTRALIA

rocker lubrication

Post by Chris Berry »

I have been discussing with some of my Australian counterparts the lubrication issues I had with my overhead gear (seizing valves etc). The suggestion was made that I should have a stronger flow of oil thought the rocker gear than the current ooze. It was also suggested that I check the flow coming from the two drillings above the rockers (seen in photo). On my rocker cover however these drilling have been sealed off for some reasons. Can someone suggest a reason for this. Does it have something to do with different models, oil pumps etc. My engine is stamped 1951 with a cast iron head and hairpin valve springs. Can anyone enlighten me as to why these drillings would be sealed off..
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Rob Harknett
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Re: rocker lubrication

Post by Rob Harknett »

I do not think there is a need to get concerned about rocker lubrication. Prewar bikes were only greased occasionally. The fact most of these bikes are still running on the same parts after some 80+ years, is testimony enough, the rockers do get sufficient lubrication. Problems only arising when parts like valves and guides are changed. They don't fit, seats come loose etc. Had they been left untouched they would probably still keep going without giving any problems.
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1608
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Re: rocker lubrication

Post by 1608 »

How do you know they have been deliberately blocked, or are they just gummed up, they are very small. If they have been deliberately blocked it may be some ones misguided belief in sorting out a smokey engine. If thats the case then sort out the reason for smkiness, wear etc.The rockers and valve ends don't need much lubricating, but the oil feed was put there for a reason. it all saves on wear and makes for a quieter engine. Even if the head is a later one than the rest of the engine then its a good modification. There is also an oil feed directly above the small well that then feeds into the exhaust valve, thats important as the singles have a reputation of valve stem over-heating and seizing. I personally would clear all oil ways.
56G80S
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Re: rocker lubrication

Post by 56G80S »

I wouldn't normally disagree with Rob but I thought thoil from those little jets wen down the pushrod tunnels and lubricated the cam followers as well.

I replaced the axles and bushes on my G80S decades ago and they have no noticable wear despite many long trips and tens of thousands of miles.
It's certainly not an "oopze"
I did cut the side off one of those transparent containers for washing machines tablets and fitted in place of the rocker box cover so that I could see what was happening. Those little jets were pushing out oil quite well once warmed up. I also have a break in the feed pipe from the front of the oil pump up to the rockers with a transparent hose connection and oil goes through there at a steady rate.

It's certainly not an "ooze"

I don't think that AMC would increase cost putting in something that wasn't required, they shouldn't be blocked and once the straight SAE 50 (asking for trouble here) warms up I'd expect a spurt; when I check the tappets there's always plenty of oil present.

Johnny B
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Rob Harknett
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Joined: Mon Jan 01, 1990 12:00 am
Location: ESSEX UK

Re: rocker lubrication

Post by Rob Harknett »

Anything intended / standard should be clear like oilways. 1937 was the first year AJS had oil going to the top end. Matchless when the AJS engine was used with a mag at the back. In 1937 oil went to the back of the sealed rocker box. ( Valve springs still not enclosed. ) Oil, from 1937 onwards DID drain down the push rod tubes, offering lubrication to the cams, on its way back to the sump.
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