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Which Grade Emery Cloth For Head/Block Finishing?

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Vincent This post is not being displayed because the poster is banned. Unhide this post / all posts.

Fisty
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PostPosted: 12:30 - 06 Aug 2015    Post subject: Reply with quote
The mating surfaces? Scotchbrite.
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MCN
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PostPosted: 12:51 - 06 Aug 2015    Post subject: Reply with quote
+1 for the Scotchbrite (I like that name).

Just have an eye for the edges as the soft backing/design of the pads can slightly round off edges that need to be square. It weakens the support for gaskets.

I'd rough off the pasted on bits using a scraper then finish with a pad.
Poke some rags down the holes to keep abrasives out the oil galleries etc.
Unless you intend to wash the parts before assembly or woteva.
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MCN
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PostPosted: 15:20 - 06 Aug 2015    Post subject: Reply with quote
Vincent wrote:
I've got this far:-

https://i77.photobucket.com/albums/j71/Drewskovitch/Jap%2070s%20bike%20toys/Bike%20toys/P1010021_zpsslaal3q1.jpg
https://i77.photobucket.com/albums/j71/Drewskovitch/Jap%2070s%20bike%20toys/Bike%20toys/P1010022_zpskpog5ru5.jpg


I'd be too proud to fit that now. Smile

Looks good.

Those Flapper wheels are Flipping expensive though. Shocked.

I use an old Bastirt (you know what I mean but the Karma-bot knows too) file with the teeth grinded off and the end ground down/beveled like a wood chisel.
That is a Scraping Tool as used by Fitters to do the precision finishing of metal work. They are also used to finish the babbit of VLDE marine units.

https://www.amusingplanet.com/2013/03/the-largest-and-most-powerful-diesel.html


Cast Steel is impervious to most any other surface so you just have to be canny with it and not gouge out any metal with the old gasket.

If you are really handy you can blacksmith an old file into a proper Gasket Chib. They are easy to use and can save lots of sweat and effort in the right hands

Chib
(a) Scottish parochial for a street weapon. The weapon may be a regular weapon, like a machette or a knife, but is often an improvised weapon like a club with a blade embedded in it, or a hammer.
(b) Scottish parochial verb for injuring someone with a hand-weapon of some kind.
(a) How dae ye like ma chib, big man, no bad, eh?

(b) See you, ya tool, ah'm gonny chib you, ya radge.
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MCN
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PostPosted: 16:05 - 06 Aug 2015    Post subject: Reply with quote
Vincent wrote:
There's a few scratches from the flapper wheel I'd like to iron out before fitting.


Remember if the scratch is 0.3mm deep (for example), to remove that scratch involves removing all the material around it. Sad

That is into 'warp factor' as you cannot/it's difficult to remove material from a significantly large surface evenly 'by hand'. Or normally things that are better surface ground in a machine (skimmed).

Pardon the patronisation

https://www.youtube.com/watch?v=526C23KXSSI


The fibre part of head Gasket will squeeze but Fire Rings are less forgiving.

It is generally ok with a new gasket but don't baaaw too much if it fails on you next year or on the last bend at Caldwel in the 2015 Classics.

I'd normally have got fed up and clashed the hoowur together by now, so I can't really talk. Embarassed
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jimspeed
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PostPosted: 16:45 - 06 Aug 2015    Post subject: Reply with quote
I usually use a 400 grit stuck to a piece of glass and rub the head over it with plenty of water or light oil. You don't want any marks you can feel with a finger nail really. Just make sure there is no grit trapped anywhere afterwards as that could ruin your day pretty quickly.
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WD Forte
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PostPosted: 17:26 - 06 Aug 2015    Post subject: Reply with quote
Flour grade
Not granary tho Laughing
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MCN
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PostPosted: 17:58 - 06 Aug 2015    Post subject: Reply with quote
Vincent wrote:

That's why I want to use a block.........I don't think anything is as deep as 0.3mm though.


jimspeed rule of thumb is anything that catches your finger should (technically' be polished out. Baaat that is manufacturer Blueprint style grade assembly.
In critical areas it is important to be flawless i.e. between oil-water ports under fire rings etc. Anything in the spaces between could probably be ignored. Your head looks fine. Rub down with a oily rag should suffice.

If you have a sheet of glass.... Everyone has one.
You can clean the surface, smear some metal polish on the head and rub it over the glass in figure of eights.
Clean off the polish, without polishing it any more, and see if it shows any high spots. They will be more shinier than the duller low spots.

Use a steel rule and a sunny window and draw the rule edge along the surface of the head. Any low points will show as bright points of light.

Like Baily's Beads
https://en.wikipedia.org/wiki/Baily%27s_beads

That may depress you though.
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Pete.
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PostPosted: 18:24 - 06 Aug 2015    Post subject: Reply with quote
Lap them flat. You are supposed to use a lapping plate but some people have used thick plate glass, it all depends what you call 'flat'. It's not unusual to find several thou of difference in the flatness of the head and barrels especially on the barrels between the cylinders.

Have a look around for an old cast iron surface plate nearby. even if they are out of calibration or a bit rough/rusty they will be plenty good enough for lapping so long as there are no dings in the surface. Buy or make some lapping paste.
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Pete.
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PostPosted: 20:11 - 06 Aug 2015    Post subject: Reply with quote
Vincent wrote:
With it being an aftermarket gasket, there's a good chance it'll leak after a short while anyway, whatever the state of the surfaces.


No reason at all why that should be true. Bolted faces can be made steam or air (including combustion) tight with no gasket at all, it all depends on what you call 'flat'.

If you were near me I could map both head and barrel surfaces for you and tell you exactly what you have.
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132.9mph off and walked away. Gear is good, gear is good, gear is very very good Very Happy
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Pete.
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PostPosted: 21:16 - 06 Aug 2015    Post subject: Reply with quote
Vincent wrote:
I've got this far:-

https://i77.photobucket.com/albums/j71/Drewskovitch/Jap%2070s%20bike%20toys/Bike%20toys/P1010021_zpsslaal3q1.jpg


Middle cylinder's been detonating. No gasket is going to survive that.

Look, don't take this the wrong way but neither of those faces are fit for sealing a gasket even an OEM one IMHO. You've got them nice and clean but I'd wager nowhere near flat and the surface finish is poor.
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kramdra
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PostPosted: 23:41 - 06 Aug 2015    Post subject: Reply with quote
The reason aftermarket gaskets fail is because the fitters have usually fucked with the surface Laughing You made it look shiny, but the flatness is fucked. It will probably still work, engines are not that fussy.

Flatness is easily measured. Blue a surface plate or thick glass to get the high points which can be corrected by hand using a scraper.

Scratches are irrelevant, if the surface is flat, the gasket will do its job.

https://www.youtube.com/watch?v=8hEMTmM1mBQ
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Pete.
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PostPosted: 23:57 - 06 Aug 2015    Post subject: Reply with quote
kramdra wrote:
The reason aftermarket gaskets fail is because the fitters have usually fucked with the surface Laughing You made it look shiny, but the flatness is fucked. It will probably still work, engines are not that fussy.

Flatness is easily measured. Blue a surface plate or thick glass to get the high points which can be corrected by hand using a scraper.

Scratches are irrelevant, if the surface is flat, the gasket will do its job.

https://www.youtube.com/watch?v=8hEMTmM1mBQ


You can't measure flatness with blue, you can only tell whether it's flat or not. If it's more than 0.0002" out of flat there will be gaps, but you don't need anywhere near that tolerance for a head gasket face. If you get a full blue print on a cylinder head or barrel you can stop right there.
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Pete.
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PostPosted: 23:59 - 06 Aug 2015    Post subject: Reply with quote
Vincent wrote:


Did you notice the repairs?

img]https://i77.photobucket.com/albums/j71/Drewskovitch/Jap%2070s%20bike%20toys/Bike%20toys/Block%20repairs_zps9nbjabvk.jpg[/img]


The one on the left is a factory repair of a casting void. They probably both are, forget about them.
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132.9mph off and walked away. Gear is good, gear is good, gear is very very good Very Happy
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