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E: Engine Lapping head into barrel video

craig

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VOC Member
20210513_HeadLapToday1.jpg
Is there a video of some competent Vincent mechanic lapping the heads in to the barrels.
Description of the exact brand name and grade of compound used , application technique, etc.

Then a show of how you hold the barrel and head and apply pressure and twist.

Then a clean up and inspection and possibly reapplication.

I realize these bikes are quite new and maybe we haven't had the time or need for this.

Thanks
Craig

The machine work was done 7, 8 years ago , i didnt like my current measurements on fit up altho they seemed close, so this is a follow up by me .

Should i just chuck these heads up in a lathe and make sure i have couple thou clearance head to muff?
 
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timetraveller

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VOC Member
I can tell you how I do it. I hold the head in a vice with the open hemisphere upwards. I hold the barrel in my hands. I use fine valve grinding compound on the narrow face and coarse on the broad face. I continue uintil there is an even colour on both faces all the way round. I clean everything upwards, as often as I need during the process, to inspect the faces and re-apply fresh compound as needed.
 
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davidd

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VOC Member
If I used compound, I would prefer the water-soluble compounds from clover as a good wash will remove any grit.


I specify the fit with the head when I have the liner made, which is not much use to you.

David
 

vibrac

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VOC Member
A few words from time traveler beats a video but then I realise I am old school
I have recently on my forays into other makes of motorcycle come across a product called timesaver paste I made a note to try the coarse and finer pastes on those two surfaces its advantage is in what happens to any stray paste and lack of embedded particles
 

Bazlerker

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VOC Member
I had my heads skimmed to ensure that the liners were squeezed between the head and the muff. The setup involved several dial gauges and a very skilled machinist with an encyclopaedic knowledge of Vincent’s..
 

timetraveller

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VOC Member
I've had that done as well. Once you have it set up then it is a good idea to do the base of the muff as well to enxure that the axis of the bore is perpendicular to the line across the main bearings. That way low clearance pistons should not lock up. As you say, it needs someone with the correct equipment and knowledge to do it properly. Roy Robertson did mine.
 

timetraveller

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VOC Member
I hold the head in soft jaws with the line between the valves across the vice and clamp it onto the fins near to where the four holes which take the holding down studs go. You will need a vice with a five inch opening. From memory the gap across the wide face is supposed to be three thou when the liner flange is hard up against the head. However, Vincent is a proper engineer,I am not.
 

oexing

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VOC Member
Well, I do 0.03 mm - as most of the worldwide poulation of 6 or 7 billions do - well except some millions in third world countries like USA or UK stuck in stone age . . . . .

Vic
 

Cyborg

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VOC Member
Where is a pic of a Vincent head held in a vice hemi up?

I don't seem to have a vice with a large enough opening.
Thanks
Craig
Is your vice wide enough to hold 2 pieces of rod that are a cylinder bolt width apart? You could use cylinder studs if you have any extras that are trash. Slip the cylinder over the two rods set up so they are below the surface of the muff. Add something to protect the bottom of the liner. With some fiddling you can get the barrel so it won’t move. Then rotate the head. It isn’t the ideal way to do it, but it’ll work.
 

BigEd

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VOC Member
VOC Forum Moderator
I have a piece of hexagon bar with a 14 mm thread turned on the end to that I clamp in the vice If I am working on the cylinder head. Plenty of adjustment.
If you are not working to micron tolerances, a rough rule of thumb is 0.1 mm is 0.004".
 

Bill Thomas

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VOC Member
I have a piece of hexagon bar with a 14 mm thread turned on the end to that I clamp in the vice If I am working on the cylinder head. Plenty of adjustment.
If you are not working to micron tolerances, a rough rule of thumb is 0.1 mm is 0.004".
I don't think it needs even that much ?.

And for a bar , Just weld anything into an old Spark Plug body ?.
 

oexing

Well Known and Active Website User
VOC Member
Old farts in Vincenteering may know better but I cannot see a need for much more than one thou / 0.03 mm gap between head and cylinder liner flange. You just want a tad more load on the flange than on the large face of head. Get that gap much more and don´t be surprised about warped cylinderhead and muff. I prefer to have a wide contact head-muff sitting firmly bolted up , don´t think you get a better seal with three thou but only deformation in components.

Vic
 

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