camshaft bush grooving

[1660bob]

Hi All, pondering the lubrication of my cams, I note that the outer lobe on each shaft has a drilling straight through to the gap between the oilite bushes, and so enjoys full continuous oil supply, but the drilling in the innermost (Inlet) lobe emerges in the centre of the inner oilite bush, and relies on a small flat milled into the cam spindle,(with which it momentarily aligns once per cam rev)to get any decent supply of oil for the cam face. Iffy at best, as for most of each turn of the cam the feed hole is blocked off by the spindle. I have read an article in Whitakerpedia by Ron Kemp, who suggests grooving the cam bush to connect the oil hole to the gap between the bushes inside the cam, and thus improve the flow so it is continuous.

Has anyone tried this mod? Is it still accepted as worthwhile, or are there any arguments against? Cheers, Bob.

 

[ogrilp400]

G'day Bob,
The Vincent engine oiling system is adequate at best. To give you an idea of just how basic it is, have a look in the oil tank when you start the bike up and watch as the return oil oozes back to the tank. The is the return side which is about 30% larger than the pressure side, so consider the amount that actually goes to the engine. Most of it goes into the crankshaft with the remainder going to the cylinders and whats left going to the cams. Now imagine that little bit thats left getting out the oil holes in the cam lobes, not very much at all. The cams get most of their lubrication from oil thrashing around in the timing case. To get an idea of how much oil gets around there, just run your engine with the ATD cover off. There is a small amount that dribbles down from the rocker gear as well. For all that, many Vincent engines have covered vast mileages on this basic oiling system.

 

[chankly bore]

And this is one of the reasons that "Oilite" bushes were used in a lot of places on Vincents.

 

[mercurycrest]

Has anyone tried this mod? Is it still accepted as worthwhile, or are there any arguments against? Cheers, Bob.

Yes, about 35-40 years ago. I did a couple of slow, spiral grooves in the cam bushings to see what improvement there were. In the end I decided the oil ran from the inner hole and ends up where it belong anyway. Lots of work for nothing,
Cheers, John

 

[greg brillus]

This is one very good reason NOT to use thick oil in your engine.....thick oil is for large reciprocating engines of large capacity, big clearances. Aircraft engines, Harleys, agricultural engines....did i mention Harley's......A Vincent although also a 'V" Twin is definatelly not a BIG clearance engine. The cams and followers are the highest loaded component in an engine....Vincent engines, as much as i love them......have pathetically small cams and followers. The two Phil's should have spent more time learning from Rolls Royce and thier mistakes with the famed Merlin engine, who's cams were also too small. By contrast most American engines had Big cams/ followers with a much larger surface area to share the load.....point being....use no higher than a 20/50 weight oil and keep the cams drowned in oil. There are those who may dissagree on this...but that is just their opinion.

 

[Big Sid]

I did the Kemp suggestion on my drag racer way back . Never ate up cams , but I used racing oil anyway . Sid .