Reusing Solid Head Gaskets

[bezabill]

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

[bsa-bill]

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

[LJ.]

Welseal is very good.

[RichardL]

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]

[dpaddock]

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

[dpaddock]

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.

[RichardL]

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.

[Richard]

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

[A10Boy]

Er, I was wondering -- why not just buy a new one ??

 

[RichardL]

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.



 

 

[bezabill]

do you no whre i can by one for a 1949 star twin solid copper

[A10Boy]

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 ?

[groily]

'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 . . .

[A10Boy]

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

[RichardL]

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.