With an exhaust valve stem running red hot how long would you think they last ?
E: Engine Oil Consumption: 100 Miles Per Pint…
- Thread starter lee_812d
- Start date
It is a bit puzzling to me why there seem to be troubles with lower valve guides, mainly ex guides, when having another second guide at the top . So not much of side loads from rockers I´d say. What might be critical is the perfect line-reamed valve gear, meaning top and lower guides concentric to the valve seats. This is not an easy job to do in the workshop and lapping in valves following a questionable guides renewal will not get all components in line . You just get a sealing valve - but still on one side. So I imagine with a heated up engine you´ll have bending/sideloads on guides and possibly seizures from this flaw. This will wreck the lockring and guide in time.
I don´t like guide seals except in ohc engines with a lot of oil supply to cams above the guides. This is not the case in Vincents, the oil supply is modest and not quite above the guide. So I would not think seals to be so essential. BUT you have to see the channels around the guide deep enough for draining collected oil down the pushrod shrouds.
I do chamfers on the guide top edges for "scraping off" oil, no NBR or FPM / Viton as in modern engine valve seals. So hopefully this will do in my engines after I was extremely attentive to concentric valve components.
Vic
chamfer on guide top:
I don´t like guide seals except in ohc engines with a lot of oil supply to cams above the guides. This is not the case in Vincents, the oil supply is modest and not quite above the guide. So I would not think seals to be so essential. BUT you have to see the channels around the guide deep enough for draining collected oil down the pushrod shrouds.
I do chamfers on the guide top edges for "scraping off" oil, no NBR or FPM / Viton as in modern engine valve seals. So hopefully this will do in my engines after I was extremely attentive to concentric valve components.
Vic
chamfer on guide top:
I shouldn't think so. When I had my issue, there weren't any seals fitted. It was a standard guide as such, shortened as it should have been as MK II cams were fitted. I have since replaced these with MK III cams. I now have seals fitted on all four valves and a widget on the offending one.
Steven
How many of you out there had experience of operating one of these, for those who do not know what it is, it`s a radial arm drill, and with my experience of them from those days, mid fifties, it does not fill me with joy. It rather explains to me why I have found two cylinder heads the same.
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Talking of tools Trev, I think I have read flywheels were only bored one at a time ?,
I am just about to weld 2 together for boring,
And the balance holes are not in line,
I had planned to fit tubes in some , To align the wheels up,
But can only use mainshaft holes and the big hole at the other end, " Comet" !,
And the smallest hole at the top, A bolt in that.
No wonder some bikes vibrate more than others !?.
Cheers Bill.
I am just about to weld 2 together for boring,
And the balance holes are not in line,
I had planned to fit tubes in some , To align the wheels up,
But can only use mainshaft holes and the big hole at the other end, " Comet" !,
And the smallest hole at the top, A bolt in that.
No wonder some bikes vibrate more than others !?.
Cheers Bill.
Delboy's comments were just what I was hoping for. The advantage of this forum is that there is a lot of experience to learn from. ClevTrev is probably right that the vales are red-hot but then it seems there are people who have not experienced problems with using seals. The more people who can let us know their experience, good or bad, the better chance we have of finding where faults arise. I never heard of lower valve guided coming loose when our bikes were younger so is this a problem of age, incompetent assembly, use of seals or something else?
And really, although some may disagree, what is the reason for seals on exhaust valves? When the piston is in suck mode, the exhaust valve should be shut and sealed tight, so not able to suck oil down the guide,
Well in 2010 I brought the Rapide to Europe (The Woolly) spent 3 weeks in the UK, then over to France, Belgium, Holland, Germany (Rally), Austria (Rally), Italy, (Rally) and back through Monte Carlo and up the Rue de Napoleon and back to the UK, 9 1/2 weeks and several thousand miles, used one litre of oil for the whole trip, NO seals on the Exh guides, so more than just a good theory. That was two up with full luggage and as some may tell you, I am not necessarily easy with the throttle hand......
That by the way, was after 8 weeks across Australia in 2007. Only used some oil on that trip after the gasket on the No 1 Rocker feed bolt banjo split, everything else stayed dry. Still running that engine untouched for about 70 K miles and still uses very little oil.....
That by the way, was after 8 weeks across Australia in 2007. Only used some oil on that trip after the gasket on the No 1 Rocker feed bolt banjo split, everything else stayed dry. Still running that engine untouched for about 70 K miles and still uses very little oil.....