Cylinder Liner fit to crankcases

[Big Sid]

Probably the biggest single material mistake in the std motors was the use of soft easily machined steel for flywheel discs as it lost its grip on both main shafts and crank pins under severe running . The Picador project failed at the reliability tests until far harder steel was substiuted there along with Vibrac steel con rods . The main shafts were heavily stressed themselves in severe use , as were the Mills pins rarely ever not severed , cut across , as the shafts tended to turn in the wheels under the hard riding drag racing owners , particularly in the States .
The works seemed a bit surprised by all this not foreseeing the heavy abuse their machines were to be subjected to , instead they saw them as high speed touring mounts and tireless at that task , which they were absolutely the best at that way of riding . An occasional sprint or hill climb as gentlemen were want to do was tolerated quite well . But repeated drag starts at high revs took its toll .
But even here with a little prep in the build up to prevent such problems all was well under this punishment . My own drag racer was perfectly reliable over 3 years of week end runs . Such a joy . And trophy winner . Sid .

 

[riptragle1953]

When fitting oversize sleeves to carefully bored and honed oversize muffs at .006" interference.... it must be remembered that when heating the muffs to insert the liner the muff has expanded in all directions. So, When I would fit a liner I would run to a jig
i build for the hydraulic press and let them cool under many tons of pressure insuring the muff lip is the .125'' from the muff flange as it should be and the muff has not cooled leaving a proud surface under the muff lip.

 

[The VOC Spares Company Limited]

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.

BOB DUNN’S VIEWS ON THE FIT OF THE LINER IN THE CRANKCASEMOUTH
Neville Higgins MPH 626 Pae1 17

Bob tells me that what happens if you have liners which fit tight into the crankcase mouths (which I thought I liked) is this:
1. The liner is round on the outside until you shrink the muff onto it:
2. When the muff contracts its irregular section squeezes the liner out of round, inside and outside. Some of this distortion extends below the muff on the liner o/dia.
3. You then bore the cylinder, which makes it round (more or less!) all the way through, but the o/d below the muff is still out of round.
4. You push the liner down into the close fitting crankcase mouth, which then tries to force the out of round o/d to be round, thus making the formerly round bore squiff shaped.
Bob therefore recommends that liners, below the muff, should be 0.005 inch less in diameter than the crankcase mouth into Which they fit, so that they remain round at the bottom of the bores when fitted. His experience is that piston oiling is not critical, and many engines run without it: he uses it himself, but more for piston cooling than for lubrication, so leakage between the liner and the crankcase is not of any real consequence.


I had a long exchange with ONE customer in Australia on this matter whilst he insisted that Phil Irving’s design could not be wrong and I insisted that in light of 60 years of hindsight things will change, we agreed to differ. I was going to put in a comment here about the Irving-Vincent not being the same as B Rapide but changed my mind.

We have sold over 60 liners in the last 2 years 1 complaint, is this a case of “put 3 Vincent owners in room and get 5 options”.

Ian Savage

 

[Big Sid]

Sid here . I repeat on the liners fit in the case mouths . If you can rap them with the heel of your fist and they go right down thunk then there is no problem , this with the left side nuts loose , center and front . Way back Dick Busby and Dave Matson stopped using the rear thrust face oil feeds with no problems . Sid .

 

[Pushrod Twin]

I prefer to have nothing to cause a change in bore size if I can avoid it.

If you have bored out cases and you choose to go back to 500 per cylinder, you can also use an aluminum sleeve that has been coated with Nikasil. As long as you run the correct rings for Nikasil they are very durable. Any old muff except the early series D die cast ones will do as the intereference fit does not need to be as high as the "tight" ductile iron liners. Carleton Palmer has run his cylinders this way for years. I have run the thin walled version for stock cases. Neither of us has found a difference in performance between the two.

David

David, could you please explain a little more about Nikasil liners? Being a long time Guzzi owner who has witnessed Nikasil cylinders with huge mileages & no problems, I am keen to do this to my Vincent.
Are you suggesting that we can use a standard Vincent muff with an aluminium liner fitted into it, but with with less interference than an iron liner would have?
What interference would you recommend?
Is the liner Nikasil plated before or after being fitted to the muff?
Are "standard" Vincent pistons used, as in, VOC Spares supplied type pistons with the normal amount of cam ground on the skirt?
Does anybody cast one piece aluminium cylinder/muff assemblies and supply them with pistons as a kit like Gilardoni do for Moto Guzzi?

To offer a little to Chris' question, FWIW, Guzzi liners are a rattling good fit in the crank cases. The skirts can be 3.3mm to 5mm thick in the wall, depending on the model, & protrude from the base of the muff about 64mm unsupported. I would be happy for Vincent ones to be the same.

 

[b'knighted]

I’m running a Nikasil bore in a big Comet. The man to ask for details is Bob Dunn who prepared the engine.

 

[timetraveller]

A clarification for some here. Nikasil is a method of electroplating whereby a layer of nickel alloy is deposited inside the liner. Many riders are now using a different and possibly more modern system, whereby a ceramic layer is deposited inside the liner. I do not know the trade names of the latter system or which firms do it but there are several people in this field. There are advantages with either system but for those of you contemplating going down this route you do need to be clear that there are two very different, and alternative, technologies available.

 

[riptragle1953]

I used a carbide based ceramic fusion developed by Dan Swain.... hard stuff that there carbide!

 

[Big Sid]

Sid . There was another liner coating process called Scanimet , or near that spelling . Anyone recall this one ?

 

[davidd]

David, could you please explain a little more about Nikasil liners? Being a long time Guzzi owner who has witnessed Nikasil cylinders with huge mileages & no problems, I am keen to do this to my Vincent.
Are you suggesting that we can use a standard Vincent muff with an aluminium liner fitted into it, but with with less interference than an iron liner would have?
What interference would you recommend?
Is the liner Nikasil plated before or after being fitted to the muff?
Are "standard" Vincent pistons used, as in, VOC Spares supplied type pistons with the normal amount of cam ground on the skirt?
Does anybody cast one piece aluminium cylinder/muff assemblies and supply them with pistons as a kit like Gilardoni do for Moto Guzzi?

To offer a little to Chris' question, FWIW, Guzzi liners are a rattling good fit in the crank cases. The skirts can be 3.3mm to 5mm thick in the wall, depending on the model, & protrude from the base of the muff about 64mm unsupported. I would be happy for Vincent ones to be the same.

I have run Nikasil in the racer. It was originally done by John Renwick. I am using the same cylinder that he plated almost twenty years ago and I do not run an air cleaner. Here in the U.S. we use Millennium Technologies in Ohio. If you send them a sketch with the liner dimensions, a piston and a muff they return it ready to install. I believe the interference fit of the sleeve to the muff is about .001". Thus, any muff but the series D diecast muffs would be suitable. You can also measure the spigot in the head and specify a slightly taller one on the sleeve if necessary. You can specify the length of the sleeve to fit the piston. I run a full skirt in the racer, but Pat Manning has been running slipper pistons for the street bikes in Nikasil bores. Make sure that the rings supplied to you are suitable for Nikasil or supply them yourself. The series D Shadow Pat rode at the North American rally this year had Nikasil cylinders.

As far as I know, nobody had done a cylinder and liner in one piece.

I suspect there is someone in NZ that would do the same as Millennium. At worst, you might have to order the sleeve from another supplier. John Renwick used to turn them from solid, but the chips would fill the shop. Millennium bought a sleeve manufacturer a few years ago, so it is one stop.

http://www.mt-llc.com/cylinder.php

David