As the cases are good support and a wonderful heat-sink..... when fitting oversize liners I would not reduce the liner o.d. but rebore the cases to grip with a.002'' interference fit with tight case studs.
Cylinder Liner fit to crankcases
- Thread starter Chrish
- Start date
A heat-gun around the case spigots..... and, if used, my silicone sealing method allows for a wee bit of case division without breaking the case seal. Once loosened this way they can be lifted with care.
A follow up on case sealing , this dealing with cylinder base gaskets . These were originally very thin , close to onion skin , thus was to limit the gasket crush so losing the torque settings on the main cy. stud big nuts and need to Retorque . Later gaskets were much thicker and softer thus needing to be retorqued on occasion as they crushed thinner .
Bill Jean on several of our motors went to a modern upgrade here , he provided a shallow groove at the inner edge where the liner exits the muff so an O ring snuggles into the groove lying just above the surface
Bill Jean on several of our motors went to a modern upgrade here , he provided a shallow groove at the inner edge where the liner exits the muff so an O ring snuggles into the groove lying just above the surface
Continuing , got away from me , sorry . The O ring at the juncture of muff and liner does several things . Not only very effectively preventing oil loss here but also prevents it from going up between the inner surface of the alloy muff and the liners surface to lessen heat loss effectiveness . But it also allows for a muff to crankcase thermal path to suck heat out of the barrels into the case via this new path . The top end runs cooler and the cases warmer better riding themselves of moisture down below . Sid .
As mentioned in previous threads, the Victorian Section has correspondence between P.E.I. and the Spares Co. about liners being supplied with no registering diameter immediately below the muff. He always advocated, and DESIGNED, a snug fit/ slight nip cold,and was unhappy with those supplied with .005" clearance. I would advocate a size to size fit if using new crankcases and modern pistons and the current fuel. I would also use premium fuel because it burns cooler, apparently!
This is almost as recurrent as the "oil thread". Series A bikes (the original and the best) had to have the crankcase bolts backed off to remove the cylinder. Most Series A bikes had Iron barrels. Postwar bikes were all alloy and it was advised that there should be light interference fit between liner and crankcase. Think about it; IF there is a compression of the liner in the crankcase mouth it could reduce the interference fit of liner and muff at the base and lead to poor heat transference and distortion leading to a possible seizure. Then again I am a chemist not an engineer. My liners have about half a thou interference fit in the crankcase mouth, fitted 12 years ago, many thousands of miles, no leaks. Several people who have bought liners from the VOCS recently have thrown them into the bin. There is a problem there! I understand that certain Jaguar liners are suitable for purpose.
The only reason I can come up with lower the sleeve diameter to not be a tight fit with the case is ease of insertion....... horrible idea.
Using the same reasoning, pistons fit easier if you leave those pesky rings off,
Using the same reasoning, pistons fit easier if you leave those pesky rings off,
There are many engines having wet liners , a slide in fit sealed with O rings only . Very fine motors .
Looking back at Vincents Glory Years , all those records were set worldwide with original pieces just as drawn in the old Parts Books . Nothing not designed by PEI in his prime . Black Lightnings , breathed upon Shadows and Rapides. , all based on the factory production pieces ordered from Bellville or the Works . The knowledge already existed , proven technique . Little reinventing was necessary beside a few bucks and a good tuner . Or a new Lightning .
So many I've known tried to reinvent them , tried to " improve " on things . Mostly unnecessary and unsuccessful . Sid .
Looking back at Vincents Glory Years , all those records were set worldwide with original pieces just as drawn in the old Parts Books . Nothing not designed by PEI in his prime . Black Lightnings , breathed upon Shadows and Rapides. , all based on the factory production pieces ordered from Bellville or the Works . The knowledge already existed , proven technique . Little reinventing was necessary beside a few bucks and a good tuner . Or a new Lightning .
So many I've known tried to reinvent them , tried to " improve " on things . Mostly unnecessary and unsuccessful . Sid .
On liner fits . And source . Our experiance with marvelous machining by Bill Jean . We obtain oversize liners from Coventry Spares made by LA Sleeves . 40 or 60 thou oversize . The muffs are made identical top to bottom with ends parallel , same height .
The ID bores of the muffs are bored and honed to identical dimensions , dead straight , expanding mandrels used to hold them . The top is shaped to accept the liner flange . The flange recess in each head is refreshed and dimensioned to accept the liner up top . The faces of the head and muff top are to be flat and parallel . After lapping there will be a gap between the broad faces of 4 thou . This pulls down tight upon torquing the cylinder and heads down to 30 / 32 ft. Lbs ft torque .
The new sleeves are turned true and sized to be a 6 thou interferance fit within the prepped muffs , both surfaces now straight and parallel for max thermal flow , cool running . The liner id is bored and honed after insertion to the desired size . We like a skirt clearance of 4 thou with modern pistons as insurance against skirts picking up . The projecting portion at the bottom is turned down to a snug slide in fit in the case mouths with the left side case nuts backed off at center and forwards .
Insertion is made hot and afterward the assembly is left in the press until all is cool .
All this seems a bit much but is necessary for good performance and trouble free operation . Sid .
The ID bores of the muffs are bored and honed to identical dimensions , dead straight , expanding mandrels used to hold them . The top is shaped to accept the liner flange . The flange recess in each head is refreshed and dimensioned to accept the liner up top . The faces of the head and muff top are to be flat and parallel . After lapping there will be a gap between the broad faces of 4 thou . This pulls down tight upon torquing the cylinder and heads down to 30 / 32 ft. Lbs ft torque .
The new sleeves are turned true and sized to be a 6 thou interferance fit within the prepped muffs , both surfaces now straight and parallel for max thermal flow , cool running . The liner id is bored and honed after insertion to the desired size . We like a skirt clearance of 4 thou with modern pistons as insurance against skirts picking up . The projecting portion at the bottom is turned down to a snug slide in fit in the case mouths with the left side case nuts backed off at center and forwards .
Insertion is made hot and afterward the assembly is left in the press until all is cool .
All this seems a bit much but is necessary for good performance and trouble free operation . Sid .