Tonight I took out the rocker feed bolts. I had enlarged the feed holes to 1mm last year. I think I will drill two holes 1/16" diameter in there now. I think I can enlarge those holes and it won't really make any difference to the oil flow down into the head. Now that I have inspected the whole thing it looks to me as though there is a bigger restriction where the oil has to come out of the bolt. The oil comes out two small holes at the top of the thread, Those holes are only 1/32" but from there it has to go down two tiny holes where it can oil the rocker bushing. The only oil that goes down past the rocker bushing has to get through the clearance around the rocker shaft. There is barely any clearance for the oil to get through. I think that enlarging the holes in the rocker feed bolts last year as everyone suggested was a complete waste of time! I think I will drill a 1/16" hole in the center of the rocker feed bolt. That oil will drip (or hopefully spray) on the top of the rocker arm and make it's way down the push rod tube. Where the oil goes back into the tank the hole must be around 1/4" diameter so I don't think a few holes 1/16" are going to prevent the oil getting back to the tank.
ET: Engine (Twin) Cam Wear
- Thread starter Nigel Spaxman
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- cam wear
Take care that you do not starve the rocker pin/rocker bearing surfaces of oil. On the locking bolts I have put TWO holes top and bottom , all 1 mm diam. Then I have enlarged the oil feed holes in the rocker bearing as well (approx 2mm each) plus I have created a small 'well' to help guide oil down the drillings to the rocker bearing surfaces - see picture. Any oil that does not go through the drillings to the rocker bearings will make its way around the rocker bearing outer then eventually down the pushrod tubes.
With the motor running there is a lot of air currents inside the timing chest pushing oil droplets in all directions so a straight drop from any point cannot be assumed.
Here is a question. when the jiggle wires were introduced (remember them?) Was the bolt hole enlarged? It's always important to keep an eye on the designers original intentions and designs like lightening the cam wheels don't think that the two Phil's had not thought deeply about most aspects.
I would say the Jiggle wires as you called them, did very little.............The real cause was the oil hole drilling in the rear of each barrel being too high up and effectively injecting oil straight into the piston rings.
A lot of Vincent's have done a very high mileage as touring machines over the years. In the 1950's Tony Rose did 100,000 mile test on a Vincent without any major work been done so even though the oiling system of the engine is fairly basic, it does its required job on a standard machine. So to me it looks like you have a specific problem with the assembly of your engine and parts clearance Nigel rather that looking at the general lubrication system as the std holes in the rocker feeds have not been a problem on most bikes.
I've never believed that oil coming down the pushrod tubes contributes much to cam lubrication as everything is thrashing around at several thousand RPM and a drop of oil is going to get swiped out of the way before it can get to a cam surface. The fact that oil in general is been thrashed about by everything moving in the timing side will be the main lubrication source along with the oil supply through the timing cover to cam spindles which should work to the cam surface through the small holes in the cams which are sometimes missing. Just try running your engine without the mag atd cover for a minute, oil will go everywhere.
Just a thought, putting my engineers head on.
Simon
I've never believed that oil coming down the pushrod tubes contributes much to cam lubrication as everything is thrashing around at several thousand RPM and a drop of oil is going to get swiped out of the way before it can get to a cam surface. The fact that oil in general is been thrashed about by everything moving in the timing side will be the main lubrication source along with the oil supply through the timing cover to cam spindles which should work to the cam surface through the small holes in the cams which are sometimes missing. Just try running your engine without the mag atd cover for a minute, oil will go everywhere.
Just a thought, putting my engineers head on.
Simon
Very strange I hate using my android predictive text
I was trying to say that you ignore the original design details especially in the engine with care they did think deeply about most aspects
My brother-in-law worked for a very short time in the stores at Ross Motors in Hinckley, Leicestershire. I think this was his probably his first job on leaving school so this would be around 1959-1960. He remembers people coming in and asking for "the little bit of wire that stops the engine smoking and using too much oil." From this, my guess is that "jiggle wires" had more to do with restricting the oil flow to limit oil going down worn valve guides. A bonus would have been that any "jiggling about" the wire did helped to stop the hole blocking up. (He also remembered they moaned about the few pence that the tiny bit of wire cost.
) Swings and roundabouts; a restriction meant less oil to the guides but also to the rockers and cams where it might have helped in an area of a high sliding load. If the hole was enlarged, perhaps to try to help the cams, the "jiggle wire" would have been an easy and cheap way to reduce the flow again without having to replace the rocker bolt.
Going back to Nigel's original concern relating possibly to having too little oil getting to the rockers assembly. On the way to a distant French Rally about 35 years ago my Rapide suffered a serious squeaking noise coming from the front rocker. I removed the cap and found a bone dry rocker chamber. Long story short, the 188 1/4BSF x 1/2 setscrew had been accidentally replaced by a 589 setscrew which is 1/8th of an inch longer. That was enough to block-off the oil-hole adjacent to the hexagon of the ET100 feed-bolt.
Just passing-on what might be a useful tip for someone...
Peter B
Just passing-on what might be a useful tip for someone...
Peter B
That's a good point Peter. Also, I would worry whether enough oil was going back into the tank to prevent sumping!
Given the number of times on this site members have recommended anyone new to Vincents to start by getting `The bibles', a quick look at the Lubrication System chapter of Richardson clearly states that later Vincents were fitted with 20 thou. metering wires into the 1/32" holes. There were no worries about cam wear in those days. I would suggest looking elsewhere for the cause.
Ray
Given the number of times on this site members have recommended anyone new to Vincents to start by getting `The bibles', a quick look at the Lubrication System chapter of Richardson clearly states that later Vincents were fitted with 20 thou. metering wires into the 1/32" holes. There were no worries about cam wear in those days. I would suggest looking elsewhere for the cause.
Ray
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Something similar happened to me. The guy my parents bought the Comet basket case from had purchased stainless nuts and bolts. I didn’t realize the supplier had substituted longer bolts for the ones that hold the oil lines to the rockers. Same result, the feed holes were blocked. The bike would start up and ran fine, then once things warmed up, the exhaust valve would stick open. Took awhile to figure that one out.