The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: RichardL on 05.12. 2008 14:49

Title: Reusing Solid Head Gaskets
Post by: RichardL on 05.12. 2008 14:49
I will soon be removing my cylinder head to sort out an oil leak.

After much consideration, soul searching and advice, I've managed to make myself almost sure that I will continue to use a solid head gasket. (This, while appreciating and without disregarding certain advice to the contrary within this forum.) This time, instead of a propane torch, I'm planning on doing the annealing in a bed of fireplace coals accelerated with a hair drier as a bellows. I think I can get up to 700 or 800.F by this method and hold it there, resulting in a more even annealing.

My questin is: Is it possible or likely that a once-used gasket will have already been compressed to the point where it will no longer take to the imperfections when the head is retorqued?

Any thoughts? Maybe I'm just thinking too cheap, but it seems that one of the benefits of solid head gaskets would be reusability. 

Richard L.
Title: Re: Reusing Solid Head Gaskets
Post by: bsa-bill on 05.12. 2008 17:08
As I understnd it manosound  the gasket will harden in use and the point of annealing is to soften the gasket and bring it back to original condition so that it will form a seal when refitted.
You are doing the right thing by managing to heat the whole gasket at once.
The other question that often pops up is wether to quench the gasket or not, apparently with copper it matters not as it does not harden when quenched

All the best - Bill
Title: Re: Reusing Solid Head Gaskets
Post by: RichardL on 05.12. 2008 17:28
Bill,

I think you have said the key thing that refreshes a memory (quoted below). Annealing causes grain growth in the copper, therefore, there should be some recovery from squishing and work hardening caused by torquing down the head. That's my new thought but I would like to hear from others, as well.

Richard L. 


bring it back to original condition
Title: Re: Reusing Solid Head Gaskets
Post by: groily on 05.12. 2008 18:05
I'm on side with all this. Get it to cherry red all over, and either leave it to cool in air (which is what I did) or quench, makes no real odds. When it's been through that, it ought to be, noticeably,  a zillion times more malleable than before you started, and will be ready to be squished again. As far as I know there is no limit to the number of times this can be done. But, like you Richard,  I am sensitive to the eloquently-expressed and knowledgeable views of the fans of the composites, even though I'm not going there myself. I've done best part of 10,000 miles since I had head trouble last year, with a reused copper gasket, and no problems and no oil leaks (which is where I started too). But it's only a cooking GF engine! After all your hard work, do hope you find your studs etc are all in perfect shape.
Have to say that my A10 has become so extraordinarily first-kick reliable that I have nothing at the moment to say except - It's great! Wish other things hereabouts were as predictable . . .
Title: Re: Reusing Solid Head Gaskets
Post by: RichardL on 05.12. 2008 20:25
Groily,

Good to hear from you and quite comforting to hear of 10,000 miles on a solid head gasket, though, I wonder if it makes a lot of difference that I am running at 9:1? SRM tells me their solid gaskets are well-annealed unless they must buy from a less-preferred alternative source in a pinch. Since I am placing an order with SRM in any case, for the now-cheaper-to-me price around GBP6, I don't think I can resist buying a new one. One thing about the old one was that I had done a makeshift lapping job on it to take away the stamping burrs. Regarding the studs, they seem to be in quite good shape. Once I corrected the washer situation, changing to Grade 8 steel, I was able to put around 38 ft. lbs. on them comfortably.

As for first kick, that was not my experience this season. I think I might have missed the timing mark by a little, for which I cannot compensate with the auto-advance pinion.

Richard L.

Title: Re: Reusing Solid Head Gaskets
Post by: Richard on 05.12. 2008 20:30
Richard
I was once told that if you quench the gasket any crud on it will be easier to clean off
Wether this is true or not this is what I tend to do, as it makes no difference wether it is quenched or cooled slowly to the annealing proccess
Richard
Title: Re: Reusing Solid Head Gaskets
Post by: RichardL on 05.12. 2008 20:34
Agree that quenching makes little difference, as the reference material indicates. However, very interesting about separating the crud, which must have a different rate of contraction than the copper and, therefore, chooses not to stay onboard.

Richard L.
Title: Re: Reusing Solid Head Gaskets
Post by: groily on 06.12. 2008 00:19
It's good that the ole greenback has picked up a bit Richard after the artificial lows of 2008. Also good - from my point of view! - that the Euro remains strong and petrol is down from Euro 1,45 a few weeks ago to about Euro 1,04 today. Shame my old age pension will be in currently lousy pounds - but it may pick up on the bootstraps of the dollar - these things have a cyclical nature. The old pound sterling is an orphan currency now, more inclined to follow the dollar than anything else, it's just a shame that the country is close to bankrupt whatever its government might say! So it may take a while . . .
I doubt whether your compression ratio would make all that much difference to the gasket's reliability, although 9:1 is rather more than I can boast with the cooking motor. If SRM say their gaskets come well-annealed, I'm sure it's true. You'll be able to tell anyway by whether it's nice and soft. There are those who say that ANY new copper gasket should be annealed afresh to be sure, but can't comment on that. If your surfaces are good and the studs are good, it should easily seal things up at 38 ft lbs and there shouldn't be any oil leaks. As to cleaning, I'm no expert - I just cleaned mine with a modern carbon-tet semi-substitute after annealing, got it looking crud-free and shiny all over, and put it in. And no probs since  - touch wood. Check-tightened after a couple of hundred miles - but all was just fine and it was a waste of time (but well spent in my view). I chug along at 60-65mph most of the time, so not stressing the thing too much. 30-35 mph in 2nd, 45-50mph in 3rd. If I want to go mad I get the Yamaha out . . . and bore myself silly.
Title: Re: Reusing Solid Head Gaskets
Post by: Beezageezauk on 06.12. 2008 10:52
I had cause to replace a piston on my A10 whilst camping on the Isle of Man this year.  Fortunately I was using a solid copper head gasket and annealed it by warming it to cherry red using two camping gaz stoves prior to quenching it in cold water.

The idea of the two stoves was, of course, to obtain an even temperature but on the quenching argument I don't know if quenching makes any difference in the annealing process.  However, I agree that if the gasket is left to cool naturally it retains its used, black, dirty appearance but if quenched the crud lifts off into the water and the gasket looks much brighter.  In fact it goes back to an almost new appearance.

Check to see how pliable the gasket is before it is annealed and then test that the annealing process has worked by comparing the pliability of the gasket after it has cooled down.  There should be a considerable difference.

In fact I am running my A10 with 2 (yes two) solid copper head gaskets, both annealed at the same time on the Isle of Man and I will post the reason for this in the near future.

Beezageezauk.



Title: Re: Reusing Solid Head Gaskets
Post by: dpaddock on 06.12. 2008 23:26
I'm astonished at the ingenuity of our corespondents; camp stoves, used gaskets, two gaskets, etc.
I suppose when the source of gaskets and other spares dries up, we'll have to resort to these means.
Meanwhile, I suggest we subscribe to the maker's intent and soldier on; BSA engineering is still pretty damn good for our A7's and A10's. (And for the Goldie, et al.)
Meanwhile, I won't be happy to read here that welding the head to the barrel is the ultimate cure . . .
David
Title: Re: Reusing Solid Head Gaskets
Post by: RichardL on 07.12. 2008 01:13
I have to think that the two-gasket approach might have been brought on by excessive head skimming. That was almost the case for me on discovering that the"machinist" had skimmed my head with a field plough. Hmmm, weld the head to the barrels? Great idea. I'm running out to the garage right now to do that. More to follow.

Richard L.
Title: Re: Reusing Solid Head Gaskets
Post by: bezabill on 07.12. 2008 11:32
but can we by new ones from eney one or  is that cheting *problem*
Title: Re: Reusing Solid Head Gaskets
Post by: bezabill on 07.12. 2008 12:27
i made one out a copper boiler it wiz a bit crap?? lol
Title: Re: Reusing Solid Head Gaskets
Post by: bezabill on 07.12. 2008 12:29
it dident leek but it wiz a bit thin he he
Title: Re: Reusing Solid Head Gaskets
Post by: bsa-bill on 07.12. 2008 12:43
Now then Bill how did you get four pushrods to work through those five holes

PS don't take this seriously  *smile*

All the best - Bill
Title: Re: Reusing Solid Head Gaskets
Post by: bezabill on 07.12. 2008 12:50
rember its a star twin it wiz actually a very good fit 2in double hole and 1 in each single hole and bobs your uncle

na bother
Title: Re: Reusing Solid Head Gaskets
Post by: bsa-bill on 07.12. 2008 17:06
Well there you go, learn something new every day, I did not know there was that much difference.

cheers Bill
and may I say how nice this forum is to read and post to, no bitching, no politics aand no whinging
Brilliant

All the best - Bill
Title: Re: Reusing Solid Head Gaskets
Post by: LJ. on 07.12. 2008 17:35
Welseal is very good.
Title: Solid Head Gaskets - Annealing Attempt
Post by: RichardL on 09.12. 2008 04:59
If you are sick of hearing about annealing and quenching and so forth, and you can't imagine how anyone would waste his time on such poppycock, this would be a good time to avert your eyes, turn you head and click on Solitaire (I almost said "cough".)

As previously threatened, I have attempted annealing an old head gasket using my home fireplace. I did try using my wife's hair dryer as a bellows and got a smoke-filled room and ash all over the place. It did, however, create a very hot fire, though it was not necessary for getting the gasket to glow. Just leaving it buried in a bed of well-going coals seems to have been enough.

I did two cycles of heating, the first quenched in water and the second allowed to air dry. On quenching, some, but not all of the scale flaked off, maybe because the gasket could not go directly from glowing to the quench (I had to carry it to the kitchen, a slight miscalculation). For the air-dried sample, there was more scale on the part, but what was left took no more sanding to remove for a given area than that left after quenching.

After each cycle I did a crude deflection force test, as pictured. I tried to see what force would be necessary to deflect a portion of the gasket 1". After the first cycle, the force required was 700-750 gms. After the second cycle the force required was 525-575 gms. Keep in mind that this was a really informal test with me trying to read the scale calibration and deflection at the same time. Also, the gasket did not stay in the coals the same amount of time each time. At minimum, this test should have, of course, started with two unannealed gaskets cooked in the same fire for the same amount of time. After those shortcomings, good science continued to be butchered. Nevertheless, the force differences were enough to identify a true difference in the extent of annealing.

As conclusions, I do not believe it was air cooling that made the second test softer. I am fairly certain it was getting cooked a second, and probably longer, time. The amount of scale that formed was a bit troubling, as it takes some aggressive sanding to remove. I tried a steel wire wheel but it was eating away at the thickness of the gasket.

Below are some pictures from the effort and a link to a very short video meant to embarrass myself.

Just in case it is not obvious, it is really cold in Chicago, and the prospect of meaningful riding any time within the next three months is looking slim. Therefore, I am significantly distracting myself.

Richard L.

http://www.youtube.com/watch?v=cOul-aIO_lg[/img]
Title: Re: Reusing Solid Head Gaskets
Post by: dpaddock on 10.12. 2008 07:46
I like your style, Richard!
Following up on this with some Googling, it seems that when one gets a uniform red oxide (cuprous), the annealing temperature's been reached. A black oxide (cupric) forms above this temperature, indicating that you're definitely annealed.
Removing the black oxide requires chemicals - a 10 to 20 percent sulfuric acid dip is effective. I would expect that wire brushing tends to quickly work-harden the gasket surface (but not the whole gasket, of course).
Your charcoal bed is probably the best heat mechanism for this purpose since it is quite uniform and thorough. The video is most enlightening!
David
Title: Re: Reusing Solid Head Gaskets
Post by: dpaddock on 10.12. 2008 20:58
Color of the heated gasket can also be used to determine its temperature - red visible in daylight is approximately 900F which is the lowest temperature cited for copper anneal; cherry red is the upper temperature limit, 1400F, which is getting a bit extreme.
Title: Re: Reusing Solid Head Gaskets
Post by: RichardL on 11.12. 2008 03:35
OK, I did an acid bath with what I had - Muriatic Acid (31.45% Hydrogen Chloride). This almost turned into a dangerous folly as I was doing it in the garage and a cloud of hydrogen chloride gas started coming off the tray. Yes, I know, not too bright. I immediately moved the tray outside, getting just one disturbing inhale of gas in the process. The photos show that the acid bath did a lot of good, mostly in the first 10 minutes. I think the remaining scale (cuprous or cupric?) is due to the outside air  temperature, about -7 deg. C basically stopping the reaction, but I am not enough of a chemist to say for sure (obviously). Maybe the movement of the scale into the acid neutralizes the acid. If you know, I'd like to know. If it's the temperature, I'm going to find it difficult to overcome for about 3-1/2 months.

Here are the before and after pictures.

Richard L.
Title: Re: Reusing Solid Head Gaskets
Post by: Richard on 11.12. 2008 12:14
Richard
it's a lot easier and probably safer just to clean the gasket with fine wire wool thats all I have ever done
Richard
Title: Re: Reusing Solid Head Gaskets
Post by: A10Boy on 11.12. 2008 13:24
Er, I was wondering -- why not just buy a new one ??

 ;)
Title: Re: Reusing Solid Head Gaskets
Post by: RichardL on 11.12. 2008 14:28
A10BOY, There seems to be a general opinion that new gaskets are not soft enough to deform to the imperfections of heads and barrels. I know everyone else's bikes have no such imperfectuions, but mine does. Of course, the gasket won't take to every scratch and knick, as you won't get that kind of force without driving the bolts through the head or twisting them off. I'm just looking for a mild flow due to broadly applied force. The question of new or used has, I think, become irrelavent in the annealing issue. I have, indeed, ordered a new gasket and intend to compare it with one I've annealed.

I have a saying about things like this with regard to my own psyche, "It's gone from a need to a mission."

Richard, I tried some very fine wire wool and the remaining scale just polished up. My obsession may reuire me to do another heating cycle to see if more instantaneous quenching does a better job of casting off the scale.

By the way, I'm just sitting on the train on the way to work, so I'm just trading 30 minutes of reading a novel for the same time ranting about metalurgy, if you could call my amateur efforts "metalurgy."

Richard L.



 

 
Title: Re: Reusing Solid Head Gaskets
Post by: bezabill on 11.12. 2008 14:50
do you no whre i can by one for a 1949 star twin solid copper
Title: Re: Reusing Solid Head Gaskets
Post by: A10Boy on 11.12. 2008 16:14
There is a school of thought that goes like this.

The original thickness was say 50 thou and it deformed by 5 thou when compressed, say 10% of its thickness.

When you anneal it, it doesn't go back to its original thickness, it will expand a bit but not that much, so it will be say 47thou. Then when you use it again, it will be thinner to start with, and if you use it over and over it will get to the point where it will not be thick enough to deform by the required amount to do its job. Personally, I wouldn't use one more than two or three times even with annealing.

Has anyone used composite gaskets with iron heads ?
Title: Re: Reusing Solid Head Gaskets
Post by: groily on 11.12. 2008 16:19
'fraid I don't know about that bezabill - but Richard, I'll bet your annealed gasket is softer than a brand new one if you apply your deflection test. I've found some new copper ones pretty hard actually, and have annealed them anyway on engines that have been a bit doubtful in this department. Not as picturesquely or entertainingly as you did yours though! I'm sure the next chapter on your train-ride read will say something about the grades of copper sheet you can buy and what the advantages are (says he with tongue well up cheek). Then all we'd need is a way of stamping them out by the dozen and sending them to you for destruction testing and pyrotechnic DVDs that are better than the pix from the Hubble telescope.

And I think A10Boy is probably right about the consequences of incessant re-use. Have never quite got as far as that, but there probably IS a practical limit to the number of times the thing can go through the fiery furnace, then the wringer, etc. Hope never to find out what that limit is . . .
Title: Re: Reusing Solid Head Gaskets
Post by: A10Boy on 11.12. 2008 16:46
Beezageeza

I saw your story in the BSAOC Mag, blimey what a pi$$er to happen on the way to an event like that. If I remember right you have two different compression pistons fitted, have you changed them now ?

Best of luck
Title: Re: Reusing Solid Head Gaskets
Post by: RichardL on 11.12. 2008 16:58
Groily,

"LOL" is wholly insufficient, you almost had me in tears. I forget where you are geographically in the French quarter, but you may be amused that I'm reading a book about Paris (not really a novel), so unless it's has to do with copper-clad Mansart roofs (they discuss them being lead), I think the possibility is slim for making a link.

Richard L.
Title: Re: Reusing Solid Head Gaskets
Post by: LJ. on 11.12. 2008 17:07
Richard... Yes I remember now the disapointments you had with the head being skimmed that left a poor surface and the need now for the imperfections to be filled by a well annealed gasket. I've had a brain wave!...

With us reading about the use of 'two' gaskets recently I wonder if you could use one thicker copper gasket...? Instead of the normal 2mm size gasket, maybe a 3 or 4mm, the thought I had here is that a greater thickness of annealed copper might result in a softer gasket that would fill the imperfections better than a thinner one would. (I'm having a job in putting this across in a written format) Hope you see what I mean.

Title: Re: Reusing Solid Head Gaskets
Post by: Beezageezauk on 11.12. 2008 20:13
A10Boy,

Yes, I did the write up especially for the BSAOC Mag but I,ve posted it in the "Stories & Chat" section of this forum for all to read.  For the benefit of this forum I think I've entitled it "Why 2 Head Gaskets?" but originally it was called Challenges of the Isle of Mud Rally.  Unfortunately I couldn't add the photographs here for some reason.

Again yes, the engine is running with a 7.25 and a 6.75:1 compression piston fitted but that alone shouldn't give me this particular problem.  Obviously it must be a variation of the gudgeon pin (wrist pin) to  piston crown heights that is causing it.  Anyway the engine will be pulled down over the winter to have replacement pistons, cam followers and camshaft fitted.  Then hopefully only one gasket will be required and the annealing process will be repeated.

How's that for getting back onto the thread??

Beezageezauk.

 

 

   
Title: Re: Reusing Solid Head Gaskets
Post by: A10Boy on 12.12. 2008 16:36
The best Ive ever seen LOL
Title: Re: Reusing Solid Head Gaskets
Post by: RichardL on 08.02. 2009 17:25
A10BOY, There seems to be a general opinion that new gaskets are not soft enough to deform to the imperfections of heads and barrels. I know everyone else's bikes have no such imperfectuions, but mine does. Of course, the gasket won't take to every scratch and knick, as you won't get that kind of force without driving the bolts through the head or twisting them off. I'm just looking for a mild flow due to broadly applied force. The question of new or used has, I think, become irrelavent in the annealing issue. I have, indeed, ordered a new gasket and intend to compare it with one I've annealed.


Following up on the experiment I showed on 9 Dec '08, and as noted in the above qoute from 11 Dec, I have tested a new SRM head gasket without my own annealing versus two others after various annealing methods and states of use. The one thing I changed in the experiment was the amount of observed deflection (from 1" to 1/2") to avoid work-hardening my new gasket.

1) Once-used, fireplace annealed gasket as shown on 9 Dec (not reused after annealing): Avg. for 1/2" deflection = 432 gm.

2) Spotty, propane-torch annealing job after removal from from engine due to leakage and no further annealing: Avg. for 1/2" deflection = 626 gm. I think this is, clearly, work hardened.

3) Brand-new gasket from SRM with no further annealing: Avg. for 1/2" deflection = 418 gm.

So, the good news is that the stock head gasket, at least this one, does not need any further annealing.

Attached below is a photo of #2 (referring to the above item, but the colloquil definition applies, as well). It is rather obvious by the venting tracks why I was leaking oil at the barrel/head joint and experiencing hard starting and questionable performance. A caliper on the gasket showed the venting tracks to be 0.002"-0.004" thinner than the areas that obviously sealed. I assume the difference in thickness was due to the erratic annealing method.

I hope this is interesting.

Richard L.
Title: Re: Reusing Solid Head Gaskets
Post by: unclemeat on 09.02. 2009 09:15
Just to add to this discussion...I'v also had many heads in the past with a certain amount of imperfections, so... after annealing the copper gasket, i put a really small amount of GREEN HERMETITE (this stuff is not to be confused with the other types of gasket sealant as it sets rock hard) on both sides of the gasket. It fills those little irregularities and seems to do the job with no leaking head joints.
Title: Re: Reusing Solid Head Gaskets
Post by: BSA_54A10 on 09.02. 2009 10:30
Well I will add my 2ps worth here.
Copper will absorb carbon at elevated ( red) heats.
The hotter the copper the more carbon that gets absorbed.
If you manage to get enough carbon in there you will end up with a copper-carbon alloy referred to a "tough pitch" copper.
This alloy will have high carbon hard spots and as such is not particularly suitable for use as a gasket where uniformity is essential.
Heating the gasket in coal file will definately cause carbon to be absorbed.
If you have to use such a heating device then it is best to use coke rather than coal as the former releases far less free carbon during the burning process.
Commercially foundries pouring pure copper and high copper alloys ( without zinc) use charcol as a flux to prevent the formation of tough pitch copper.

If heating with an oxy torch then you should set it to be a little on the lean side ( excess oxygen).
If you are using an air/propane torch then you should do it in a small furnace and use reflected radiant heat ( heat the bricks red hot). A simple furnace can be made from a couple of fire bricks top & bottom with some 1/2 bricks to make the walls. I use old broken bricks from the lining of my wood stove, which are readily available & quite cheap.
Such a simple enclosure will easily attain 800 deg C with nothing more potent than a disposable propane torch or even a gas ring running towns gas.

About quenching.
In theory it will make absolutely no difference how you cool the annealed gasket as the copper has a continious phase from red hot to room temperature so there is no phase change to surpress ( or induce)
In practice you have to be careful if you quench as you can set up thermal stresses if the quenching is not done properly.
Usually I pop another fire brick on top of the gasket after I have finished annealing to ensure a slow & even cooling.
A full soft gasket will be indented by your thumb nail and is what most copper mills use to quickly check sheet stock is full soft as doing a proper hardness test on thin copper sheet is a bit tricky.

About cleaning.

Copper should be cleaned in an reduceing acid such as Nitric acid or acetic acid ( vinegar  ) or even citric acid .
However the powers in charge have scheduled Nitric acid in most countries so we "terrorists" can not make nitro- glyserene but citric acid is available from most good cookery suppliers.
Mechanical cleaning with things like wire brushes should be avoided as it will induce work hardening.
Polished such as autosol will work quite well & not upset the apple cart as will things like chemical cleaners for Stainless steel pots.  Steel wool will also work quite well.

Hope this helps to clear things up
Bike Beesa
trevor
Title: Re: Reusing Solid Head Gaskets
Post by: bezabill on 09.02. 2009 11:09
that was a good and well spent peny,s worth,s LOL
Title: Re: Reusing Solid Head Gaskets
Post by: RichardL on 09.02. 2009 13:30
Trevor,

Thanks for the excellent technical advice. Do you think the ash wood used in my fireplace would supply carbon similar to coal. It doesn't really matter, because, if I try this again, it will be with your propane torch and firebrick method. I was not able to impress my thumbnail in the new SRM gasket, but I am convinced it is a tiny bit softer than the fireplace-annealed version.

Regards,

Richard L.
Title: Re: Reusing Solid Head Gaskets
Post by: A10Boy on 09.02. 2009 15:04
Thanks for you excellent post Mr BSA_54A10.

Quote
A caliper on the gasket showed the venting tracks to be 0.002"-0.004" thinner than the areas that obviously sealed. I assume the difference in thickness was due to the erratic annealing method.

I dunno for sure but I would have thought that this was caused by scouring due the escaping gasses.
Title: Re: Reusing Solid Head Gaskets
Post by: BSA_54A10 on 10.02. 2009 02:06
Ash by its very nature is carbon deficient so it will not lead to carbon pick up.
It is also highly alkaline so if left in the ash to cool down should come out relatively clean.
Gaskets as supplied are never full soft.
This is because they are pressed from semi hard ( cold finished ) plate.
Trying to blank full soft copper is very difficult as it tends to extrude rather than shear cleanly, jambs in the presses and is a regular PIA for the manufacturers .
Grain growth is not a problem for a gasket as it is in compression and being copper ( with FCC crystal structure) the actual grains are weaker than the grain boundary in the first place.
It dose become a problem if using extra thick gaskets ( or several) to lower compression or on really high compression engines ( particularly with blowers ).
Bike Beesa
trevor
Title: Re: Reusing Solid Head Gaskets
Post by: RichardL on 17.02. 2009 04:13
Maybe reaching the end of the story on annealing my head gasket. (I can hear our well experienced members, "much ado about nothing," or the like.)

Heeding Trevor's comments that a truly soft head gasket will deform with a thumbnail and, also, that new gaskets can't be maximally soft, else they can't be stamped, I set out for another bit of interesting information. Specifically, I called SRM and asked them if they further anneal their gaskets before installation, and the answer was "yes."

So, I annealed my brand new gasket with a MAPP gas/oxygen torch and was able to create a nice moving red glow. Referring back to my 8 February post, whereas the new gasket took an average of 418 gms for 1/2" deflection in my setup. After annealing, it only took around 225 gms. and could be dented with my thumbnail.  'nough said, it's already in the bike and waiting for rocker covers to go on next. One thing I forgot to do before yanking the bolts down to 40 ft. lb was to check my tming. Now I'm going to need to get creative with some kind of calibrated depth gauge, as has been discussed at length in the forum. I am up for working out the depth gauge, rather than doing any dismantling for using a degree wheel.

Richard L.

Title: Re: Reusing Solid Head Gaskets
Post by: groily on 17.02. 2009 08:02
This all amounts to great confirmation of the state of affairs, as well as being a wonderful pyrotechnic interlude.
I was fairly sure that new copper gaskets needed annealing to get them softer for all the reasons expressed - or anyway, I always have - and the deflection/thumbnail tests and word with SRM prove it.
I certainly annealed mine - from SRM - when it went on, and no problems at all, plus check-tightening proved to be unnecessary, although I did it anyway. I don't go as far as 40 ft lbs - and that with an iron head - as I reckon 34 ft lbs ought to be enough. BTW, the alloy heads of another marque in the shed are only meant to go down to 18 ft lbs - and the studs hold the cylinder barrels on too. But they're only 5/16th Cycle nuts on long studs (which rather encourages me to obey the book of words!). . .  Point is, cleanliness plus sensible design and careful assembly enable them to withstand pretty much the same fiery furnace as pertains in an A.
Title: Re: Reusing Solid Head Gaskets
Post by: RichardL on 17.02. 2009 12:38
Groily,

Having used 38 ft. lbs. in the previous assembly, and experiencing pressure and oil leaks, I opted for 40, as mentioned by David. However, the last gasket was not as soft. It makes me wonder if the head will warp between bolt holes as the gasket is compressed. Also, I suppose there might be some deformation of the alloy under the washers, but I've tried to hedge against this by doubling-up on hardened washers of the maximum possible diameter. I'll know more in the, hopefully, distant future when the head is next off. As for snapping the bolts, so far, so good.  In any case. it's not like I can now go back and loosen them to a lesser torque. All these fears aside, I'm hoping to have the same positive results that David (and others, I suppose) have had when using the 40 ft. lb. value. 

So, I ask myself, "why didn't I ask SRM what torque they use while I was at it?" Answer, "because I am a tunnel-visioned dolt."

Richard L.
Title: Re: Reusing Solid Head Gaskets
Post by: groily on 17.02. 2009 19:19
Absolutely NOT saying what torque should be applied Richard! Just that I tend to do 3/8th BSF fasteners to 34-35, perhaps out of fear of having more barrel threads strip on my particular A and perhaps because I spend a fair amount of time playing with more fragile things from earlier times. Happily it has worked perfectly for me since, during which time the machine has needed almost no attention despite a lot of use. Dare I say, it's as reliable as a modern? There are loads of people using 40 ft lbs I know, and it's obviously quite OK. I have a sort of suspicion that one reason for using the smaller heads on the bolts - apart from the physical space issue - was to discourage over-tightening, given the size of the wrench, pre-socket era, that could be applied. When I had my first A, I only had box spanners - the tubular things - and I challenge anyone to do anything up really well with them. But I really have no idea, I just follow instinct, likely wrong!, when it comes to not breaking things. Perhaps also comes from being a bit too large and having a tendency, painfully acquired, not to apply that final tweak which results in disaster!
Title: Re: Reusing Solid Head Gaskets
Post by: RichardL on 17.02. 2009 20:11
Oh, we're so far astray from the orginal topic no one will ever find us.

I just went and looked at some standard torque charts and found that 3/8" SAE Grade 8 steel bolts (leaving out some details like TPI) cound be torqued up to around 45 ft. lb. dry and 35 lubricated. This makes me glad I thought about this before hand and cleaned the oil off the bolts with some white spirits then dried them. Nevertheless, I'd bet there was some residual oil in the holes, meaning I am probabaly torqued-up too tight on some. The object is riding, right?

Richard L
Title: Re: Reusing Solid Head Gaskets
Post by: bezabill on 17.02. 2009 20:33
i stil cant find a solid copper one for my star twin??? *problem* *help*
Title: Re: Reusing Solid Head Gaskets
Post by: trevinoz on 17.02. 2009 21:18
Neither can I. In fact I have never seen one for the long-stroke engine.
  Trev.
Title: Re: Reusing Solid Head Gaskets
Post by: bezabill on 17.02. 2009 21:22
do you think thay are all compiset
Title: Re: Reusing Solid Head Gaskets
Post by: BSA_54A10 on 18.02. 2009 12:48
Another 2p's worth here.
If you have not done so yet google webzseums and have a look at their 1950's BSA factory promo film,
Engines rolling off the line and not a calibrated tool anywhere in sight.
The actual torque figure is a bit esoteric.
If you got 100 top mechanics to torque down the head, then measured the actual foot/ pounds on each fastener then you would have 101 different values.
What is important is that ALL THE FASTENERS ARE THE SAME , so the clamping force around the cylinder is uniform
Plus or minus a couple of pounds will make no difference, none, diddly squat, nadda, nine.
The values published are usually towards the high end to compensate for poor mechanics who do not prepare the joining faces properly.
I suppose it is a philisophical difference between the older "know the theory" generation and the younger computer & calculator generation where "the actual number is important".
All alloy motors will hold back 12:1 compressions with as little as 15ft/lbs and indeed 30ft/lbs will start to tear the threads in the alloy.
Now a cast iron head on a cast iron barrel should be able to take in the order of 80ft/lbs before you start to tear out the threads but if you have to go over 30 then there was something fundamentially wrong with the assembly.
The head bolts only have to do one thing, create a uniform clamping pressure and the  excess tension on the bolts is simply there to compensate for the bolt expanding more than the head & barrel and reducing the clamping force lower than that required to seal the combustion chamber.
Exces torque will not only stretch (& potentially break ) the bolts but will cause the head gasket to extrude into every open cavity and may in fact cause the gasket to leak.
Fire proof suit on I retire to a neutral corner.
Bike Beesa
Trevor
Title: Re: Reusing Solid Head Gaskets
Post by: beezalex on 18.02. 2009 14:02
FWIW, since there are no torque specs for A10's, I've just been using the A65 figure of 32 lb-ft since they are of VERY similar design.  Now, I realize that iron heads don't have as much thermal expansion, but the above figure should work equally well when hot or cold, no?  So, I agree with Trevor, if your barrel and cylinder faces are flat and your gasket is annealed and of uniform thickness, excessive torque can only lead to distortion and potential leakage.
Title: Re: Reusing Solid Head Gaskets
Post by: RichardL on 18.02. 2009 14:36
Well, now I am duly fearful of having a distorted and leaky head gasket. My possible solace being in the fact that some others here are also using torque values at the higher end of bolt ratings. The fact is, my surfaces may not be perfect, as I had to restore them by hand following a botched skimming job. At the same time, I have to wonder if my previous 38 ft.lbs  was the cause of the previous leaks. I need to look back at the leakage paths in the old gasket to see if there are clues.At this point, I'll go ahead and mount the rocker box so I can do a compreesion test before committing to final reassembly.

Trevor, interesting point about the lack of torque wrenches at BSA. I previously posted an article talking about the first patent dates for torque wrenches in England and it was near the beginning of A10 model life. (Can't find it now while thumb-typing on the train). On the other hand, I've also seen an article where Roland Pike appears to be talking about torquing head bolts with a torque wrench. I'll post it if I remember.

OK, my hands are falling asleep and we're arriving at the station, so, bye for now.

Richard L.
Title: Re: Reusing Solid Head Gaskets
Post by: RichardL on 24.02. 2009 10:34
Update regarding 40 ft. lbs. on a well-annealed (to the extent I could do) head gasket. Apparently, no gasket distortion causing leaks. Around 162 PSI (+/- around 2 PSI) on each cylinder after a squirt of oil to take rings out of the equation. I think I'm happy.

Richard L.