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E: Engine Cylinder Liner

powella

Active Website User
VOC Member
Pics show a turned liner with oil everywhere and this was a consequence of NOT lapping the head joint , as evidenced by the still prominent stampings on the mating faces.
My question is what are these and why on earth are they on the mating faces .hemmings 030 (2).jpghemmings 015.jpghemmings 029.jpghemmings 015.jpghemmings 029.jpghemmings 030 (2).jpg
 

vin998

Well Known and Active Website User
VOC Member
VOC Forum Moderator
The Vincent factory after boring and honing the barrel then graded them from the final measurement. The stampings I suspect are their identifying grade. It's rumoured the best went on the Black Shadow. I cannot remember where I read this though.
 

Ian Savage

Well Known and Active Website User
VOC Member
The mark's are listed in the Instruction Sheets. S, U and A often accompanied by a inspection mark, a quartered circle with letters in each section. I'll put a photo on tomorrow. Piston were also graded and matched the barrels for best fit. Your barrel was marked U then changed to an S.
The liner has clearly lost fit in the muff, they all do the later die cast muffs are worse.
 

greg brillus

Well Known and Active Website User
VOC Member
By the time you mess around with oversized liners these need the muffs boring out to begin with.......You are better off scrapping the lot and buy new liner/muff assemblies and start again. Once the top hat section is less than 0.125" in height then trying to get the liner to head joint to seal will be difficult. Also measure the height of the muff itself, if it is less than 3.030" in height then they are starting to get bellow limits, and if different from each other this will affect the compression to some extent. Been through this exercise several times and it is not worth the grief, so best off fixing it properly in one go. Good luck ...........
 

Ian Savage

Well Known and Active Website User
VOC Member
Mark's as promised, A, U and S, also all 3 barrels have an inspection stamp opposite the grading stamp. I added a clear pic of the inspection stamp from a c/case.

15963540341856490449542437600895.jpg20200802_085907.jpg20200802_085903.jpg20200712_181554.jpg
 

powella

Active Website User
VOC Member
Hi Ian
75 % of this face is supposed to be lapped to the head - how come these marks can still be seen ?

Worried of Swansea ( not Rugby )
 

Ian Savage

Well Known and Active Website User
VOC Member
Not when they are new out of the factory, they were machined to the correct clearance only a bedding in lap to the top of the liner into the recess on the head needed.
 

Cyborg

Well Known and Active Website User
VOC Member
Those markings would still be visible because they are below the surface and wouldn’t normally be completely removed with lapping unless you really went at it.... or it had been lapped numerous times in it’s life. Also the depth of the markings would have depended on the mood of the employee.
Looking at the top of the liner, it certainly doesn’t look like it was making anywhere near sufficient contact with the head as well as the liner not having much if any interference fit in the muff. It’s possible the liner was replaced in the past and wasn’t pressed home all the way after cooling and worked it way down after some miles. Both of these things combined would allow the liner to move around. That oil hole is more than likely too high up anyway. One way to deal with that would be to drop the liner, clean things up and reinstall the liner with the hole to the front and then drill a new hole in the correct spot. Not recommending you do that, because your cylinder muff is likely knackered. Greg is correct.... buy a new cylinder assembly and use that one for a door stop. I’m not sure if the cylinders from VOC Spares come with the oil hole already drilled so you may have to do that yourself... assuming you want to bother with it. If not you can just block off the oil feed to the cylinders.
I suppose one could put .003” or so worth of plating on the liner, but that seems a little nuts given the supply of new cylinders.

A24275D3-BA9A-4AFC-82D2-FAE2A596AADF.jpeg
 
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