Head gasket - which one ???

Previously wrote:

I would be grateful for some advice regarding the type of head gasket to fit to my 62 Norton Dominator 99. The one as fitted is a made up type of at least two layers.

Norvil list two types: P/T number 069092P pattern and 022141 solid copper.

The solid copper gasket part number is almost the same as the part number in the Spare Parts List i.e.T2141, so I suspect this is the type that was originally fitted.

If anyone has experiance of what type of gasket gives the best performace I would be grateful for their advice.

Regards

Tony

Hello Tony Go for the solid copper one as you can use it more than once by anealing it thats heating it up with a gas blow touch and getting it cherry red hot then dunk it in water ASP . Hopes is helps somewhat yours Anna J Dixon East yorkshire branch

Hi Tony,

I think you will find that everyone seems to like a different type of head gasket. I have used just about all of them & cant really say much bad of any of them (except a batch of patternTaiwan made ones sold by Dommiracer some years back). I will be good to hear what everyones opinion is on this. I have found that most head gasket failures have nothing to do with the gasket itself. Often a head or cylinder that isnt dead flat, wrong amount of thread on head bolts that dont allow them to be tightened all the way, ridge around stud holes, not tightened evenly, not re-torqued properly, etc, etc.

Some like the solid copper gaskets because they can be re-used, but some have complained of difficulty in oil tightness. I really didnt have issues on my solid copper on my 850 Commando that I had. Solid copper is used on many different types of engines, here is a good article on them ( see copper head gasket section about 1/2 way down) :http://www.enginebuildermag.com/Article/1260/engine_sealing_high_performance_head_gaskets.aspx

I currently am using the Norvil 069092P on my 600cc model 77 with no issues & just got one in for my model 7 project.

As to annealing the copper gaskets, my impression is that you should anneal if you are re-using a used solid copper gasket, but a new one is ready to go without annealing. I was taught to heat it to dark red, then let it cool slowly. The article Ireferencedearlier (not a Norton article) gives these instructions for annealing a solid copper head gasket:

" The best way to anneal a copper head gasket is in a controlled environment such as an air-tight vacuum oven. The gasket should only be heated until it is a dark red (about 900? F) and no more. After the gasket has air cooled, the surface needs to be cleaned with a brush or abrasive pad to remove oxide from the surface."

Technically, annealing is performed by heating the copper until it is glowing for a few moments and then allowing it to cool slowlySimplified, the atoms of copper get hot enough to allow crystal defects in the metal to reorganize into a form that no longer has stresses associated with it, thus softening the metal.If you cool it quickly (ie by quenching) you may create and "freeze" new crystal defects in place and actually make it harder. This is, in fact, one of the methods used to make copper hard, steel too.The reason you can get away with softening copper by heating and then quenching in water is straightforward- the water boils at the interface and turns to steam, the steam thus generated insulates the copper from the water and because of that, the water cannot transfer heat away from the copper fast enough to have the process actually act as a "quench". Water is not a part of the annealing equation because it can't act to cool fast enough. (borrowed from: http://www.busconversions.com/bbs/index.php?topic=6911.10;wap2&nbsp

This should be a good thread, as all of us have some sort of head gasket experience!

Skip BrolundThat's why, for example, there's this stuff called "oil hardening steel", if you were to heat it and then quench it in oil it would get hard. But if you tried to do the same using water instead it would get soft for the same reason that water quenching copper doesn't do anything. It vaporizes to steam and then is incapable of removing heat fast enough, whereas oil doesn't vaporize nearly as easily and will take the heat away fast enough to cause hardening.If you want to bone up on the subject a bit, take a quick and dirty glance at the process by looking up "heat treatment" and "annealing" in wikipedia. You'lll probably learn more about metallurgy than you want to, but it's got some accurate explanations.

i try to use copper when i can as quiet often you fi nd that the layerd once when you take them off after a bit of use end up stiking to the head so you have to carfuly scrape the residu off but copper always comes cleen off

Dominators were all originally fitted with composite or layered head gaskets. I have used both composite and solid copper at various times over the years. One thing to watch with any head gasket it to be sure that it does not protrude into the pushrod tunnels - composite gaskets are particularly prone to this. Unless checked and if need be corrected, they can wear away the pushrods with predictable consequences...

Skip previously wrote:

Some like the solid copper gaskets because they can be re-used, but some have complained of difficulty in oil tightness.

Coincidentally the solid gasket on my 99 is passing oil. I will have the head off tomorrow and report back. I did anneal it before fitting!

Cheers

Alan

Head gasket failure in a composite gasket tends to be severe - the asbestos (or whatever is used now) layer is normally spat out and you get a loud whistle every time the affected cylinder fires. With a solid copper gasket, you usually get get oil seepage, sometimes quite a flow. I had a spell of head gasket failures in an alloy head A10. I lapped the head flat and used new head bolts - thereafter it behaved impeccably.

I have helped fix a Tiger cub with a blown head gasket using copper wire wrapped round the head joint a few times. Got the guy home...

Gordon.

The solid copper gaskets are generally better value for money as they can usually be reused a couple of times. Providing that they are annealed correctly between each use.

The annealing process consists of heating the gasket evenly to a cherry red and then either dunking in cold water or allowing to cool.

The important point here is that all of the gasket needs annealing. If a narrow flame gas torch is used for a heat source then it is easy to miss a section which then remains hard and will cause weeping of the cylinder head joint.

Conversely, don't cook the gasket for too long or the thinner parts will start to vapourize. This tends to happen with the 750 gaskets near the rear headbolt holes. Solid Copper gaskets made for the early Atlaswith spiggotted barrels are very prone to thisproblem and often, after just 2 annealings, have to be junked. Mind you, the composite gaskets for the same engine are not much better unless carefully torqued down and checked regularly.

Composite gaskets are OK if they are quality items. But how do you check this??? Poorly made gaskets will cause problems around the pushrod tunnels and many often fail when the centre layer fragments and blows out frombetween the copper skins.

Composite gaskets often fall to bits when being removed from an engine that has done a lot of miles and even those from a low mileage motor generallyhave novalue as a second-hand item. However, in an emergency, where no new gasket is available, a reasonable fix is to coat the the underside of the gasket with a very thin layer of semi-hardening goo like Red Hermitite and then torque the cylinder head back down as normal. This is normally quite successful as a 'get-you-home' trick as long as no 'track day' sessions occur en-route.

Hi Phil,

The annealing process in my earlier post (3rd one from the top) may be ofinterestto you.

Thankyou for bringing this article to my attention.

It is very informative and possibly, some parts, may be worthpublishing in Roadholder.

I'm certain that many owners fit solid copper head gaskets unawarethat, to get the best out of them, they need to doa little more than just throw them in place.Also, there are quite a few other copper gaskets on most Norton engine that would benefit from annealing.

I, too, have used both composite and copper head gaskets on a Dominator. However, that was back in the '50s, when they were made in the U.K. I recently made the mistake of using a Chinese de-coke gasket set. Although not impressed with the quality, of the composite head gasket, I used it anyway (the previous copper gasket having been on for over 10 year, being re annealed 3 times). The result? blew out in less than 50 miles, and yes, the bolts were tightened, and torqued down in the correct order! Now awaiting delivery of a English made copper item. Maybe I was unlucky, and got a "Friday afternoon job", but I will not take the chance again.

Regards, John.

I like copper gaskets. The only complaints I have heard is are that they are more prone to leak a little oil than composite or flame ring ones. My response is that since it is being used on a British bike, a little oil is not anything outrageous . A tiny oil leak will not prevent you riding your bike home, but a blown head gasket certainly will!

I previously wrote:

Coincidentally the solid gasket on my 99 is passing oil. I will have the head off tomorrow and report back. I did anneal it before fitting!

There was no obvious reason why the gasket was leaking. I rummaged through my gaskets and found a new composite one but on examination it was rubbish. Can't remember where it came from; perhaps it was one of John's Chinese ones. I also had a new solid gasket and decided to use that. Unfortunately, I don't have access to the high tech kit that Skip's link mentioned so it was annealed on the gas stove as usual. I also changed the oil and altered some wiring. Bike is now running but it was dark by the time I finished and a glass of wine and dinner was more inviting than a test ride on freezing rural roads.

Cheers

My copper head gasket arrived this week, and the '54 dommy 88 is up and running. I have done about 80 miles today (in the Spanish sun!) with no apparent oil leakage from the head (yet!). If Skip reads this; valve clearances of 6 thou inlet & 8 exhaust seem about right, when using alloy pushrods with an iron head. No more loss of power, or compression when hot. Now re-starts 1st. kick. All I want now is a trailer, I am not going to ride 1,200 miles, each way, to Kent and back. John.

Previously wrote:

My copper head gasket arrived this week, and the '54 dommy 88 is up and running. I have done about 80 miles today (in the Spanish sun!) with no apparent oil leakage from the head (yet!). If Skip reads this; valve clearances of 6 thou inlet & 8 exhaust seem about right, when using alloy pushrods with an iron head. No more loss of power, or compression when hot. Now re-starts 1st. kick. All I want now is a trailer, I am not going to ride 1,200 miles, each way, to Kent and back. John.

and why not its a nice littel ride

Hi John,

Awesome news!Thanks for the heads up on your valve clearances, I hope to start assembly on my Model 7 engine this week, its a balmy 12 degreesFahrenheit (11 deg.Celsius&nbsp in the garage.

Skip

Hi,

Just to add in my 10p worth. The ONLY reason to quench a copper gasket is that a gasket at 200 degrees looks the samecolouras one at roomtemperaturebut it but it makes a bigger burn mark on the carpet.

I prefer copper on my commando andlightweights.

Regards

Tony

The point of a gasket is that it need to be malleable enough to take the shape of the mating faces and seal them. This is why you need to soften the solid copper type by heating. I'm always surprised when people talk about quenching as you don't want to risk any hardening. In simple metalwork terms you either "temper" metal by heating thenquenching in oil (even mild steel responds to this as do your screwdriver tips!) or you "normalise" by heating to a specific temperature according to the metal and allow it to cool naturally. This removes any stresses and, with copper, softens it.

Any leaks will be down to uneven or warped mating surfaces. A head is fairly easily faced down on a glass plate with grinding paste or 1000 grade wet & dry - the same as you do for shims or pumps, Obviously you remove studs first! Not so easy with a spigoted barrel, although the non-spigoted aren't a problem.

Cheers, Lionel

I have always used composite gaskets and had no trouble ,perhaps I've been lucky.

Or perhaps you've been sold the real thing, not the Chinese replica. I always use the composite ones unless the engine is on an oversize that makes the flame ring stand into the bore.

Hello all,

When I restored my 99 in the early 90's (92 if memory serves)I used a composite gasket. The bike has now done many thousands of miles,many of them in the company of much bigger, faster bikes, so it has had to work for it's living, & I have had no problems whatsoever. Also, I fitted a composite gasket to my Commando just before the trip to the international rally in France 2001, as the solid copper item was leaking so much oil, this has also served me well. I do, however,carry a spare solid copper gasket when on long trips, just incase. Why a solid copper ? Less likely to be damaged when stuffed into the spares kit, simple as that.

I should point out that I've nevr had any problems with solid gaskets, other than oil leaks.

Regards, Tim