B cylinder oil hole vs C cylinder oil hole

craig

craig

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VOC Member
It is amazing how little information is available on this subject.
Here is an early B front cyl case and you can see how wide the band is for oil porting. Also the clocking of the hole can be from rear center to many degrees to the timing side.
Center of feed port is 0.750" as pictured, this is 1947 engine 323.
0.750"matches the round hole in B barrel liner pictured above. How best to plug liner hole?
Craig
20140610_BCylOilHole.jpg
 
craig

craig

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This not making any sense! ...........were the original Vincent pistons (1946-1950) configured differently and the ring sets positioned higher on the pistons? Oiling above the oil ring is not making any sense!!!!!
 
greg brillus

greg brillus

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Craig, do not put restrictor discs in......find yourself a small countersunk screw and cut off the shank/thread area so that you have JUST the countersunk part left. This should be as good a FIT into the hole as you can, and even slightly smaller than the total hole area in size. Clean up the tapered hole area thoroughly with some emery tape/sand paper, until the hole is very clean and bare metal, scuffed up. Then mix up a small amount of Devcon or similar metal epoxy compound, and put some in the hole followed by the small countersunk screw head, then smear some more of the epoxy over the area. Wipe off the excess particularly on the inside of the liner. Even if some oozes out through into the bore area, you can scrape off the piece once it has dried. Make sure nothing is protruding on the outside as well. Once dry you can lightly sand the inner/ outer areas to finish off. Redrill a new hole alongside the original one biasing it closer to the timing side....as you know that the feed gallery is plenty wide enough to allow this. Just make sure that when you are finished that the feed hole entering the bore is BELLOW the lowest ring/ oil control ring. It only needs to clear it by 0.5 mm or preferably a bit more. It takes less time to do this than to explain......Its really not that hard, at all. This will cure your over oiling problem.......Cheers........Greg. PS make sure the bore has a good hone cross hatch pattern to assist the rings in bedding in......:).
 
T

timetraveller

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Once again I am not sure that I am following this correctly but if I am, and if the liner has turned in the muff, then it almost certainly is not a good fit and will not get rid of the heat quickly enough. Particularly in a hot climate. I used to pin all my liners into the muff with one of the original big end rollers pushed through a hole in the top flange of the liners and into the muff. This way it cannot rotate. It is a trivial task to get the old liner out of the muff. Just put it in an oven, muff to the top and let it heat up. Eventually you will hear a clang as the muff falls down the liner to the reduced diameter part of the liner. When replacing liner you must keep it under pressure while it is cooling in order to stop the liner flange ending up with a gap between it and the top of the muff. If that happens then it will continuously move down with use and you will loose the seal between the head and the liner. I do not know the characteristics of the epoxy you mention but most normal epoxies will soften at high temperatures. Whatever you do, good luck with it.
 
Oldhaven

Oldhaven

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Here is a good reference available for VOC members in full text search under articles on the VOC main site:


CYLINDER OIL FEED HOLE POSITION
Robin Blackwell MPH 413 Page 13

I used the search words: oil hole AND liner. there are also quite good articles by Mike White and Ron Kemp that show up, plus a long one by Phil Irving
 
craig

craig

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We seem to be missing some information on Vincent engines about why feed oil above the oil ring......and why the continuing factory bodge to move it down. Hundreds, if not more than a thousand Vincents were assembled with oil hole 0.750" below the muff, which now in 2014 and even in the 1960's fed oil to above the piston's oil ring. Somehow we are missing the 1946 engineering here.
Oil feed above oil ring on purpose, rod length change, piston design change...........what happened?
I understand how to move the oil hole, or eliminate the oil feed
20140611_PistonCompare.jpg
 
T

timetraveller

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Is it not possible that this was just a change due to experience with excessive oil consumption and an attempt to cure it? With seventy years of hind sight it might now be obvious that oil should be fed in below the oil control ring but would that have been the case in the 1940s when the bike was designed. Personally I do not see this as a bodge. The timing side spindles are where they are and how could you move them realistically? Instead the solution found is trivial to introduce and does the job. Remember that with more experience and modern oils this oil feed hole is no longer needed and think of all the other changes that were introduced over the years after more experience.
 
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