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#827899 10/27/20 1:26 am
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Mark Z Offline OP
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In another thread it was mentioned that someone was selling NOS or good NOS replicas, and that they were thicker than some of the pattern parts and that the oil drain holes were smaller.

I've lost track of that thread, does anyone know who that was who was selling those head gaskets?


Mark Z

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I’ve seen them on eBay in the states (least the replicas) but can’t seem to find them right now.

Here’s some NOS ones from Vale Onslow

https://www.eBay.co.uk/itm/163880042957

I’ve just ordered my self some more, I should be seen ok for life now grin With various projects and many years ahead of me.

The drain holes aren’t vastly smaller but they are a bit, and the thickness new if I remember right is 0.048” instead of 0.039” (1mm) which is what the pattern ones are. I don’t use any goop on the head gasket and the only time it’s leaked since I’ve had it on was the other month and I thrashed the snot out of it, it had a line of oil on. The cylinders (which you wouldn’t have seen had I not painted them silver) and after it cooled down it self sealed again and didn’t leak again. Shame as I think the guides are buggered as I’m getting whisps of Smoke when I accelerate.... but they are the original guides. But I digress. I never got that good a seal with the aftermarket Repop gaskets.

Last edited by Allan G; 10/27/20 7:32 am. Reason: Added more

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Mark Z Offline OP
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Allan, thanks for the tip! Unfortunately, according to website and confirmed by telephone, Vale-Onslow cannot sell to the U.S.


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Hi All
Hope this is what you need, I have bought quite a few for other bikes from Lani and 110% happy

https://www.eBay.co.uk/itm/BSA-A65-...ICK-X-76-3mm-BORE-8mm-studs/312026243577


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8mm studs????

I've found most of the pattern gaskets to be thicker than the originals rather than thinner.
Never had any problems with them sealing but i don't like to loose any compression, so
i always use the thinnest ones i have. If they have large oil holes on the forward galleries,
then just use a couple of o-rings, it's a common fix. A drop of welseal and away you go.
Don't use the composite ones they tend to be absolute crap.

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NickL, the "8mm studs" quote must be in error. We know the studs are 3/8" diam; that's 9.52mm.

In regard to thickness, Allan G. quoted .048" for NOS and .039" for pattern (i.e., "if I remember right"). These recommended by John are quoted at 1.06mm; that's .042".

I'm aware of the O-ring trick, will employ if necessary.

If it seems like I'm being a bit "retentive", oil leaking past the head gasket, presumably originating from the oil drain holes, has been a chronic problem for me, even though I've taken the baseline measures, annealing, using Coppercoat, re-torqueing. So if there's a better head gasket I want to try that.

I agree about the composite gaskets; I tried one once and it disintegrated in short order.


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thicker won't hurt. thinner might be a problem on the singles though. the barrel sticks up into the recess on the head and if the gasket isn't thick enough it won't seal right. I did a B44 once that blew smoke like a bastard until it warmed up... all due to the gasket. changed it to an OEM and all is good

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Some things to help the head seal.

When the head is flattened a coarse cut with a fly cutter to leave a finish like a vinyl record.

Spot face the head bolt/ nut seats, these are often distorted.

Thick hard washers under the nuts/ bolts.

O rings in the oil drain holes.

Retorque after a few heat cycles.

Even new copper head gaskets must be annealed before fitting.

NB The head gasket cannot self anneal in situ, this would mean the gasket got to red heat, if this happens there are other serious problems.


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Originally Posted by Mark Z
Allan G. quoted .048" for NOS and .039" for pattern (i.e., "if I remember right"). These recommended by John are quoted at 1.06mm; that's .042".

I’d have to remeasure mine, 0.042” could be correct but I’ll double check when I return home in a few days.


Now let’s all have a beer beerchug

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Mark Z Offline OP
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Originally Posted by gavin eisler
Some things to help the head seal.

When the head is flattened a coarse cut with a fly cutter to leave a finish like a vinyl record.

Spot face the head bolt/ nut seats, these are often distorted.

Thick hard washers under the nuts/ bolts.

O rings in the oil drain holes.

Retorque after a few heat cycles.

Even new copper head gaskets must be annealed before fitting.

NB The head gasket cannot self anneal in situ, this would mean the gasket got to red heat, if this happens there are other serious problems.

Gavin, what is a fly cutter? If this is a machine operation, it's not likely to happen. I can, however, face on coarse emery cloth. Same for "spot face".

Do the O-rings have to be of any special material (e.g., to withstand heat), or will ordinary O-rings do?

For this re-torqueing, do you recommend cracking all the nuts and bolts loose first, as was suggested in some thread or other?

Re-torqueing is such a PITA on a BSA because you have to remove the exhaust rockers, but I'll take the pledge here on.


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nitrile is ok viton is a bit better either will do the trick.
Ah the old exhaust rocker shaft thing, yes a pain but it's
not as if you have to do it every week eh?

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A fly cutter is used on a milling machine , it is a single point cutter, and produces a fine or coarse finish depending on feed rate.
No fly cutter, then 100 grit will give a suitably ruff finish. if you lap on a flat surface be sure to use a figure of eight pattern ,if not it will end up curved not flat.This should be done in a Zen like manner, slow and calm.
its worth seeking out a friendly mill operator, not just for flattening , its the best way to spot face the fastener seats.

Yup re torquing is a PITA , sometimes I mark with paint, slacken then retorque , noting any movement. other times I have just gone over and nipped up to torque, on my bike usually the centre bolt takes a bit more, no way to get at the front two without moving the ex rocker spindle and push rods. Its a one time deal and well worth the bother IMO.
Most important is to sneak up on the torgue 5 fitpunds at a time on initial fitting.

One more important thing, do not assume the barrel top surface is dead flat,it often isnt. It can be lapped in the same way as the head. .
Barrel to head interface can be checked by bluing the head and shimmy ing against the barrel, sometimes its just one or two high spots around the fastener heads, these can be locally scraped.

Last edited by gavin eisler; 10/29/20 9:36 am.

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Just some photos of the pattern gasket (0.039”) placed over an original one (0.049” as recently measured)

I ordered a few off Vale Onslow, only to find out that they aren’t genuine ones although probably NOS from somewhere.

FFFB3267-7072-4575-A782-D658FCB8688A.jpeg 0251634C-0BA3-4401-9E23-5DC86F16EA51.jpeg 4AC7DA7C-603C-43A2-9ECC-D9ADD8A35E84.jpeg

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Yes Allan, max is ten replies per PM. So if you don't mind I'll keep searching. There was that other reference from chaterlea25 to check out, and if I must resort to "ordinary" ones I can get them stateside in a few days.

Hmm, I have seven or eight cast-off head gaskets; I should measure them.


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Originally Posted by NickL
nitrile is ok viton is a bit better either will do the trick.
Ah the old exhaust rocker shaft thing, yes a pain but it's
not as if you have to do it every week eh?

So I guess I won't be getting those O-rings from my local hardware store - I'll ask, but my guess is, they won't even know what they're made of.


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If you go to he market place section you will probably find some one who bought a bag of 50 from McMaster Carr who will send you a few in the mail at a reasonable price.
Or you can go to McMaster yourself and do the same.
They are wholesalers so 50 is about the smallest bag they sell .


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Originally Posted by Mark Z
Yes Allan, max is ten replies per PM. So if you don't mind I'll keep searching. There was that other reference from chaterlea25 to check out, and if I must resort to "ordinary" ones I can get them stateside in a few days.

Hmm, I have seven or eight cast-off head gaskets; I should measure them.

That’s no problem Mark, id have been happy to send you the 4 genuine ones I have had the others been correct, I could get away with 1 Of my originals being sent, that way you could have had a batch made from them. I wouldn’t have been happy sending these others off knowing they aren’t the real thing. I’m a bit peeved that the seller hasn’t responded to my email for the others purchased.


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Originally Posted by chaterlea25
Hi All
Hope this is what you need, I have bought quite a few for other bikes from Lani and 110% happy

https://www.eBay.co.uk/itm/BSA-A65-...ICK-X-76-3mm-BORE-8mm-studs/312026243577


John
Lani has more stuff listed on eBay than directly on the Copper Gaskets Unlimited web site, and has a lot more available that aren't listed on either. He will also make custom gaskets if you provide a pattern, and in many thicknesses.

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Originally Posted by Allan G
Originally Posted by Mark Z
Yes Allan, max is ten replies per PM. So if you don't mind I'll keep searching. There was that other reference from chaterlea25 to check out, and if I must resort to "ordinary" ones I can get them stateside in a few days.

Hmm, I have seven or eight cast-off head gaskets; I should measure them.

That’s no problem Mark, id have been happy to send you the 4 genuine ones I have had the others been correct, I could get away with 1 Of my originals being sent, that way you could have had a batch made from them. I wouldn’t have been happy sending these others off knowing they aren’t the real thing. I’m a bit peeved that the seller hasn’t responded to my email for the others purchased.

Ok Allan, I'll get back to you on that one gasket after checking out that other source.


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the often overlooked thing about SOME of the repro copper gaskets (other than thickness) is the grade of material used .....some of it is marginal quality to say the least so obviously if the material isn't uniform it will be way more likely to blow or leak

best way i can describe it is that it looks "blotchy" ie impurities in the sheet it is stamped from......annealing material like that will only make it worse !


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Hi All
Lani's gaskets are sized to the bore/ overbore size , he will ask for the measurement, He does offer a range of thicknesses
he supplied me with a 2mm thick gasket for an A10 as the head had been skimmed to death

John

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I have six cast-off head gaskets. The one on the left in the photo appears to be NOS or a good replica. The other five are like the one on the right. My thickness measurements match Allan's; .048" for the thick one and .039 for the rest.

I'm in communication with Lani at Copper Gaskets Unlimited, and I'm aware now that he can vary the thickness, so it looks like I'll be able to get what I want. I didn't know about the bore size though; I'll have to let him know about that. Unfortunately, one of the BSAs I'm doing is .040 over, and the other is .060 over. And Lani is in the U.S. :-)

Ig, I hear you about the quality of the stock - makes sense.
[Linked Image from i.postimg.cc]


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Factory gaskets are generally cut to the maximum recommended oversize .
It does make a difference to have them cut to size
Lanni uses USA 99.9 Cu in standard USA gauge sizes, he does not do custom thickness if he can not get the sheet Cu .
We often have members bikes where the head has been shaved right into the fins cause in the "day" you could get 102 octane down here .
The usually ploy is to go with a thick head gasket and an aluminium base gasket to bring the compression back to some thing that is reliable .

People forget that over time the gaskets will get thinner from the effect of being clamped between the head & the barrels and repeated annealing oxidizing the surface .
Also British bike had the gaskets cut from British standard gauge copper sheet
Most gaskets now days are cut from copper rolled in China which is EU ( Metric ) standard gauge .
IT is not the fact that the new stuff is deliberately cheaper it is just that the stock sheet sizes are different

British std sheet gauges are different to USA standard sheet gauges which are different to EU ( metric ) standard sheet gauges .


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Well this has been a real education for me, and I'm amazed that it has taken me this long to learn that not all head gaskets are created equal.

I've ordered two head gaskets from Lani at Copper Gaskets Unlimited, .050" thick, bore hole size 3.013", which is large enough to accommodate a .060" overbore.


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Originally Posted by BSA_WM20
If you go to he market place section you will probably find some one who bought a bag of 50 from McMaster Carr who will send you a few in the mail at a reasonable price.
Or you can go to McMaster yourself and do the same.
They are wholesalers so 50 is about the smallest bag they sell .
I have a big bag of X rings for the oil union under the engine. The smallest number MC sells is 100, so I'm set for life.
It still leaks there!


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