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IC cylinder head gasket material & suppliers
| mick | 13/02/2011 16:58:02 |
| 421 forum posts 49 photos | As I have enjoyed positive responces to most of my postings regarding sourcing materials, I need to scratch your collective brains again.
This is my first and by no means last venture into IC engine building, but I've come to the point of finial assembly and need to make a couple of cylinder head gaskets.
My first question is:
Can any one suggest the best material to use, as every web site I've look at seems to suggest something different. I feel that the gaskets wouldn't need to be much thicker that 0.010''/0.015'' No materials I've so far looked at starts under 1mm thick.
Secondly and more importantly, can anyone recomend a supplier who would be happy to supply small quanties of gasket materials.
Thanks in advance.
Mick |
| MichaelR | 13/02/2011 17:17:23 |
 528 forum posts 79 photos | I would think the Gasket in a tube type would do the job, eg- Hylomar Blue, or the Silicon types of Instant Gasket which most motor part stockist keep ( Halfords ) |
| JasonB | 13/02/2011 17:42:53 |
 25215 forum posts 3105 photos 1 articles | Its easy enough to get a sheet of gasket paper, this comes in various thicknesses from about 0.005" (0.15mm) upwards, look for something like Klinger Statite or as said above one of the liquid gaskets is fine.
One supplier here plenty more if you google
On the models you can't get enough torque on the head studs to use one of the compressible gasket materials like you would on a car cylinder head.
J Edited By JasonB on 13/02/2011 17:44:51 |
| AES | 13/02/2011 17:47:47 |
 85 forum posts 1 photos | Mick,
In my (misspent) "yoff" when fiddling about with all sorts of aeromodelling engines (both diesel & glow), broken or missing gaskets were quite common (a whole group of us swapped & bought & sold engines amongst ourselves). In all cases it was common to replace broken & missing gaskets with "thickish" brown paper, as used to be used for wrapping parcels - this both for backplate to crankcase and for crankcase/liner to head gaskets.
You just took a nice clean & wrinkle free piece of said wrapping paper and used a modelling knife (if you were well-heeled, or a broken off razor blade if not) to cut round the outlines (inside hole first). Clearance holes for bolts & studs were made by using a suitably-sized brass tube sharpened to an edge on the INSIDE (bore) face (using a fine round file, then finishing off the cutting edge with said knife or razor blade and fine sand paper wrapped round a suitably sized piece of dowel).
The lay the gasket flat on the bench with a pad of newspaper underneath and gently cut the bolt hole/s using a back & forth rotating motion.
I don't know what sort of IC engine you're building but the above always worked fine back then (long-lasting too) and I've used the self same trick a couple of times since without problem.
I don't know how thick the paper is/should be, but at a guess about an Imp thou or perhaps a little bit thicker.
Hope that helps.
Krgds
AES |
| John Olsen | 13/02/2011 17:57:27 |
| 1294 forum posts 108 photos 1 articles | You could consider the use of thin copper sheet. I've used that sucessfully on motorcycle engines. After cutting it out heat it up to a dull red heat as this will soften it. regards John |
| Ramon Wilson | 13/02/2011 18:42:09 |
 1655 forum posts 617 photos | Mick,
As said , not sure what type of IC engine you need gaskets for but further to AES's reply most IC aero engines today have aluminium gaskets. A good source of supply for these is the humble coke can or some litho plate from a friendly printers. As said the object is to get the hole done first and this is always the awkward bit in ali but if you can clamp a few layers between some ally sheet and bore it this works well. Once the hole is done it's a simple matter of holding the blanks on a mandrel (clamped up tight) for turning the ODs to diameter. The can material is a bit claggy but is workable. Litho plate needs annealing before use to soften it. Waving it through a soft flame is sufficient.
Paper gaskets - I use either good quality brown paper or 100gm computer printing paper. Again get the hole done first and here I can recommend using an Olfa circle cutter. Cut the outside contour around the shape of part - backplate, front housing using a scalpel and mark off the hole positions.
I have made a tool from silver steel sharpened as per AES's brass tube and run this in the drill cutting through the paper into one of those green cutting mats - produces perfect holes. I then soak the paper gaskets in a light oil before fitting.
Hope this helps - Ramon
Edited By Ramon Wilson on 13/02/2011 18:43:00 |
| Nicholas Farr | 13/02/2011 19:26:10 |
 3988 forum posts 1799 photos | Hi Mick, you can always use Wellseal jointing compound in conjunction with brown paper or the copper/aluminium mentioned, If you are confident that both faces are relitivity flat and reasonably smoothish it can be used just on its own. There seems to be plenty on ebay.
I have used Wellseal for many different things in my work, and also including my old Beford vans engine head gasket, which was recommended in the Haynes worshop manual. It is a bit of a sticky compound, and you have to use it as directed to get the best result, but it dosen't harden or dry out.
Regards Nick. |
| mgj | 13/02/2011 20:02:58 |
| 1017 forum posts 14 photos | Brass/copper shim too - in thicknesses from .001 upwards, or metric equivalent.. Head gasket what .005". . |
| AES | 13/02/2011 20:12:18 |
85 forum posts 1 photos | Mick,
Further to Ramon's post, I agree 95%, BUT:
1. Personally I've had problems "flattening" the sides of Coke tins - perhaps I'm ham fisted, but either I don't get the old curve out completely, or I get a curve starting in the reverse direction. IMHO you really do need to cut the gasket from really FLAT material. Suggest you look for the (flat) tops of some ring pull food tinws - e.g. here we have a particular brand of coffee which has lovely flat thin ali tops.
2. Similarly I find printers litho plates a bit thick.
3. But Ramon is quite right, most modern engines do use ali for gaskets (no idea how thick really - just "very thin"!), and under those circumstances I've found that a craft knife with a fresh blade will cut ali prefectly well with minimal distortions if you're careful and take it easy (probably 2 cuts).
4. But when you come right down to it, though ali is "nice", it does seem to me from my own results that ali isn't any better (at sealing, or in longevity terms) than brown paper, so why bother with ali? (I'm assuming here that you've got a decent finish on the surfaces that will mate against whatever gasket material you use in the end).
5. Re something like Wellseal, I've never tried it on model aeroengines (worked great on a Ford 100E I was rebuilding once - remember those?), but assuming your engine is "model size" (let's say, up to 100 cc cylinder capacity) then I'd guess that Wellseal (or any other similar Halfords componds) will be not only a bit of an overkill, but also (in view of the very small mating surfaces in model engines) likely to give you problems with the compound "squidging" everywhere as you tighten up.
Anyway, several ideas to try out above, good luck with it.
Krgds
AES |
| Ramon Wilson | 14/02/2011 09:38:45 |
1655 forum posts 617 photos |
Hi AES,
Yes, 'can' material is nowhere as good as nice flat virgin sheet which is why litho plate is better but it will do and the curvature is not really a major problem. Litho plate comes in various thicknesses too whereas the can stuff is pretty consisistent. Thickness is not critical but the thinner obviously the better. I have just meaured the few spares I have and they run between .007 and .012 (inches).
The can material needs to be rolled using a smooth piece of steel on a blemish free flat surface - true flatness is not essential but this will take out the stressed in curve.
Though I have not tried it I guess the Olfa circular cutter would soon cut through it but I would still prefer to clamp a few blanks and bore out which is how I have dealt with this material to date.
Another possibilty that has just occured (though not tried) is to use a scalpel with a floating or rotating blade. If this was run around the inside of a plate with a hole cut in it - the hole taking into account the diameter of the blade holder this would probably be better. Many years ago I had to cut several thousand 'Fablon' green baize discs without cutting the backing paper. I made a cutter up with a rotating blade and this worked perfectly. I sold that on but do have a commercial item and the next time I make some gaskets which is not that far off I shall investigate to see if this is viable in ali.
This is the knife I have currently - I believe this one is an Excel but there are various makes available. The cutter guide (plate) would need to be thick enough for the tapered part to bear against - might be better to turn this area parallel. Incidentally The backing is some very nice brown paper kept specifically for gasket material
  Hope this sheds a bit more light for someone Regards - Ramon |
| AES | 14/02/2011 16:57:34 |
85 forum posts 1 photos | Hi Ramon,
Thanks for your inputs and the pic (a very "superior" if not downright "sexy" modelling knife). BTW, I use Swann Morton myself, can't roll off the table.
And I've never tried the Olfa cutter but I'm sure you're right, it should work well on thin ali, even at the cost of 1 or 2 (throw away) blade/s.
Your brown paper looks very nice too - "just what the Dr. ordered". That good stuff is still available (in my case over here, only through specialist stationers, at a pretty high price too, but it does work well for gaskets).
But I like your advice re flattening ali tins, I must try it again some day. All the (few) bits of litho plate I've got in stock are quite a bit thicker than yours (I've used it for the odd engine cowling, softened over a candle then beaten over a wooden former). Must try and get some thinner stuff one day.
Krgds
AES |
| mick | 14/02/2011 17:05:17 |
| 421 forum posts 49 photos | Hi. All
Thanks for all the good advice. As the crankcase and cylinder heads were all fly cut I'm pretty sure they are flat, so I'll give the wellseal and brown paper a go. Thanks again
regards.
Mick |
| mgj | 14/02/2011 20:03:29 |
| 1017 forum posts 14 photos | May I suggest against the assumption that something is flat because it has been flycut. Unless the axis of the spindle is EXACTLY at right angles to the table, and the jobs were set exactly level, they WILL be dished. They may be very smooth in terms of CLA, but the one thing they will not be is flat. May not be by much, but unless those criteria are met, truly flat they will not, and cannot, by definition, be. If you take a plate, tilt it and then move it sideways you will see why. One of the problems with flycutting if real flatness is necessary. Head gaskets are interesting things. I've never met Wellseal, and doubtless it works well, but I was always taught 2 things about head gaskets. - 1. Never use anything on them as a sealant. I wish I could remember why, but that's what we were taught - perhaps wrongly. Something to do with bonding to the surface. 2. Choose a material that is soft enough to conform to imperfections (of course), and whose coefficient of expansion is greater than that of the hold-down bolts. Then as all heats up the seal improves. That may well be why very thin copper and ali are two favourites. . Edited By mgj on 14/02/2011 20:09:40 |
| Gordon W | 15/02/2011 09:21:32 |
| 2011 forum posts | I've never made a small I/C engine, so may be well off course, but why not grind the head seal? My car has ground head to cylinder joints, some of the old bikes had also. Use coarse grinding paste on spigot and fine paste on the flat joint. works very well in full size. To soften ally gasket rub with dry soap, warm until the soap turns black and quench if required, this old dodge still works. |
| Gordon W | 15/02/2011 11:39:45 |
| 2011 forum posts | Just realised the obvious mistake. It should of course be fine paste on the spigot into the head and coarse paste on the flat head to cylinder joint .This gives a very small clearance at this face, and allows the spigot to seal. |
| Dinosaur Engineer | 15/02/2011 14:57:15 |
| 147 forum posts 4 photos | As Gordon W says gaskets are not always required.. If the mating surfaces can be individually lapped flat and then lapped against each other then you should get a pretty good seal. The later VW aircooled engines did not have any head gaskets. |
| mick | 15/02/2011 17:38:29 |
| 421 forum posts 49 photos | Further to my flycut heads not being flat, I have been proved wrong in the past, but after 45 years in the trade I think I've just about got the hang of this milling thing. I don't understand how the job not being level will result in a dished surface. What happens if the surface to be cut is at an angle to the rest of the component and so requires the head to be inclined, does that represent not being level? If you knock down on strips, then when the vice is released after machining the material, having memory, may very well return to its pre-machined condition. But when a component is held in the machined registers of soft jaws, or in the jaws of the machine vice, without tapping down, the resulting machined surface will be completely flat and true to the spindle, as there is no preasure to be released, so the molecular structure of the material has not been compremised and the registers in the soft jaws are milled true to the spindle, the resulting machined surface will also be true. As this was the method employed to fly cut my cylinder heads, I'm pretty confident that they are indeed flat.
A quick test would be to apply a thin film of engineers blue to a surface plate, then move the machined surface in a figure of eight around the plate and observe the result.
Regards.
Mick |
| mgj | 15/02/2011 18:34:50 |
| 1017 forum posts 14 photos | One needs to look at the gemetry in 3d to see that if a disc is inclined, then it doesn't cut flat. The tool tip travels a slightly elliptical path with respect to the reference surface direction of travel, resulting in dishing. Equally, if the table is not moving exactly horizontally, then the same phenomenon will occur. And by exactly I mean exactly to National Physical Laboratory limits, which we as engineers cannot achieve - the slack in the bearings is enough or a tad of slack in the gibs on the knee . As I said, it doesn't have to be a lot, and it might not be meaningful in the context of the job to be done by the work, it may be barely detectable, but but unflat it will be, and has to be, by mathematical definition. I wasn't having a particular go at anyone in particular - just making a general point that it can be very difficult to get things truly flat when flycutting. Actually its almost impossible, because there is always an error. Its not an accusation of casualness or incompetence - just a statement about the geometry that exists. Its just one of those things, like no straight edge is straight. Its a question of how much, and whether that much matters. And for those milling on a lathe, it certainly won't be flat, because the head of a lathe is offset with respect ot the travel of the cross-slide - and needs to be for good turning. A lathe always turns concave, or should do. Holding in a vice - there is always SOME deformation. Sorry. To every action there is an equal and opposite reaction. Again, whether it matters, mostly not of course, depends on the job. But you grip it, you have squeezed it so when you take it out the machined surface won't be the same as it was in the vice. Precision is a most awkward thing- and I agree I'm pushing the limits beyond our practical limits, but the statements are true, and as engineers I think we should understand what we do, against the day that it does matter. Please also don't get me wrong, I'm quite happy to flycut and lap on occasion, so I'm not ruling it out. Just saying that it has limitations. |
| mick | 16/02/2011 17:24:53 |
| 421 forum posts 49 photos | Like I said, my flycut heads are flat.
Regards.
Mick |
| mgj | 16/02/2011 17:33:46 |
| 1017 forum posts 14 photos | I'm sure they are. |
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All Forum Topics > General Questions > IC cylinder head gasket material & suppliers