Getting a head gasket made
Discussion
Matthew-TMM said:
I've got an engine from 1949 that will want a new head gasket when it goes back together. Spare parts appear to be non existant, and don't even appear on ebay much. Is it possible to get a head gasket made, or even make one yourself?
If you can't get one off the shelf, your best bet is to have one made in copper. You'll probably need to supply whoever makes it with a drawing.http://www.fwthornton.co.uk/index.html
give these guys a call, if they dont have what you are looking for, they will be able to get one made up for you.
give these guys a call, if they dont have what you are looking for, they will be able to get one made up for you.
I think it depends very much on how thick it has to be.
If it's dead thin, then you're probably going to have to punch the holes, and that means you're going to need to make/have appropriate punches and dies.
If it's thicker, then drills, and a trepanning bar.
Either way the material will have to be annealed. You can probably buy it that way, but if it's not actually soft you'll need a big blowtorch to do it yourself.
If it's dead thin, then you're probably going to have to punch the holes, and that means you're going to need to make/have appropriate punches and dies.
If it's thicker, then drills, and a trepanning bar.
Either way the material will have to be annealed. You can probably buy it that way, but if it's not actually soft you'll need a big blowtorch to do it yourself.
Edited by dilbert on Thursday 9th August 20:57
Matthew-TMM said:
I forgot to mention it's a little air cooled 50cc 2 stroke, so you couldn't have a simpler head gasket. I've had a look at it and it looks rather similar to a fibre washer with an embedded fine wire mesh, so not sure what kind of gasket material it is?
That would probably be a material known as paxolin(e). You may well ba able to make that yourself. If you have a drill press, a vice, and a grinder, you can make everything that you need.If you can find a holesaw the size that you need for the big hole, you'd probably get away with using that. Then you don't need the grinder and the vice. The trouble is that if it's not exactly the right size you'll affect the compression.
A trepanning bar is dead simple to make, you might even be able to buy one, and you cn set it exactly to the size you want.
Edited by dilbert on Thursday 9th August 23:33
dilbert said:
Matthew-TMM said:
I forgot to mention it's a little air cooled 50cc 2 stroke, so you couldn't have a simpler head gasket. I've had a look at it and it looks rather similar to a fibre washer with an embedded fine wire mesh, so not sure what kind of gasket material it is?
That would probably be a material known as paxolin(e). You may well ba able to make that yourself. If you have a drill press, a vice, and a grinder, you can make everything that you need.If you can find a holesaw the size that you need for the big hole, you'd probably get away with using that. Then you don't need the grinder and the vice. The trouble is that if it's not exactly the right size you'll affect the compression.
A trepanning bar is dead simple to make, you might even be able to buy one, and you cn set it exactly to the size you want.
Edited by dilbert on Thursday 9th August 23:33
Looking at it, it seems to have the wire mesh on top of a layer of compressed fibre very much like a fibre washer of perhaps 1/2 to 3/4 of a mm thick, coated on both sides with a hard coating on both sides, quite possibly a polymer of some sort. Don't know whether this helps or not.
Yes it helps lots.
That, you could make out of gasket paper. Go to your local motor factor and ask for thick gasket paper!
To make the holes and shapes in that, all you need is a big ball bearing. Place the paper over the cylinder, hold it steady, and push the ball into the head securing holes in the top of the cylinder. You might even like to tap the ball lightly into the securing hole. It'll mark and possibly even cut the holes in the paper for the screws.
Once you have them, fix the gasket paper to the top of the cylinder with the screws, and run around the edges outside and inside pushing firmly with the ball bearing. It'll mark and maybe even cut the gasket paper to exactly the shape you want.
You'll definately be able to mark the paper because it is quite soft. If the edges on the cylinder are sharp you should have no difficulty in actually cutting the holes in the paper with the ball bearing. Don't damage the corners/threads though.
If you cant get the paper to cut on the cylinder, then just use a small sharp art knife on the paper to cut to the marks you made with the ball bearing.
Gasket paper! Flipping heck. It was the thing I thought of when I first read the thread. I thought, "Nah It would never be that simple"!
That, you could make out of gasket paper. Go to your local motor factor and ask for thick gasket paper!
To make the holes and shapes in that, all you need is a big ball bearing. Place the paper over the cylinder, hold it steady, and push the ball into the head securing holes in the top of the cylinder. You might even like to tap the ball lightly into the securing hole. It'll mark and possibly even cut the holes in the paper for the screws.
Once you have them, fix the gasket paper to the top of the cylinder with the screws, and run around the edges outside and inside pushing firmly with the ball bearing. It'll mark and maybe even cut the gasket paper to exactly the shape you want.
You'll definately be able to mark the paper because it is quite soft. If the edges on the cylinder are sharp you should have no difficulty in actually cutting the holes in the paper with the ball bearing. Don't damage the corners/threads though.
If you cant get the paper to cut on the cylinder, then just use a small sharp art knife on the paper to cut to the marks you made with the ball bearing.
Gasket paper! Flipping heck. It was the thing I thought of when I first read the thread. I thought, "Nah It would never be that simple"!
Edited by dilbert on Friday 10th August 00:50
Edited by dilbert on Friday 10th August 00:52
Matthew-TMM said:
Thanks for that, so you reckon gasket paper is up to the job of a head gasket then? Never having bought it before, are there different types and thicknesses?
For that job it's fairly arbitary. I wouldn't be surprised if the head actually goes a short way into the cylinder barrel. If that's the case then the gasket is only a gas seal. In a car, it's a very different scenario, because the head never goes into the barrel.Anyhow, it won't do too much harm if it doesn't work out. Little 2 strokes like that spend most of their time in bits anyway!
The other thing, is to make sure it will turn over freely without a spark plug in it. If the clearances are tight, and the gasket is just a little bit thinner, you'll damage the piston crown, the little and big ends.
Also bear in mind that the original gasket would have been thicker when it was new. Do you have a micrometer. If not maybe the motor factor will have one, to help you select the right paper.
Edited by dilbert on Friday 10th August 01:00
cptsideways said:
The inner edge has a lip yes?
In which case gasket won't do. Surely just measure the ID & get a gasket off anything with the same ID & cut the rest away. Could'nt be simpler & cheaper.
The inner edge of the head?In which case gasket won't do. Surely just measure the ID & get a gasket off anything with the same ID & cut the rest away. Could'nt be simpler & cheaper.
If you can find another gasket the right size..... I thought that's why you were looking to make one?
Edited by dilbert on Friday 10th August 01:04
My text art didn't work out!
That gasket doesn't look like it has a crush ring to me. I reckon the inside of your head will project into the cylinder bore by a small ammount, which is the alternative manufacturer solution to the problem.
But if there's no crush ring you can use gasket paper.
That gasket doesn't look like it has a crush ring to me. I reckon the inside of your head will project into the cylinder bore by a small ammount, which is the alternative manufacturer solution to the problem.
But if there's no crush ring you can use gasket paper.
Edited by dilbert on Friday 10th August 01:09
dilbert said:
Matthew-TMM said:
Thanks for that, so you reckon gasket paper is up to the job of a head gasket then? Never having bought it before, are there different types and thicknesses?
For that job it's fairly arbitary. I wouldn't be surprised if the head actually goes a short way into the cylinder barrel. If that's the case then the gasket is only a gas seal. In a car, it's a very different scenario, because the head never goes into the barrel.Anyhow, it won't do too much harm if it doesn't work out. Little 2 strokes like that spend most of their time in bits anyway!
The other thing, is to make sure it will turn over freely without a spark plug in it. If the clearances are tight, and the gasket is just a little bit thinner, you'll damage the piston crown, the little and big ends.
cptsideways said:
The inner edge has a lip yes?
In which case gasket won't do. Surely just measure the ID & get a gasket off anything with the same ID & cut the rest away. Could'nt be simpler & cheaper.
I think the slight lip is just where the very inner edge (about 0.5mm) wasn't being compressed by the head, the lip was up inside the dome in the cylinder head.In which case gasket won't do. Surely just measure the ID & get a gasket off anything with the same ID & cut the rest away. Could'nt be simpler & cheaper.
In case you hadn't guessed, this is for the Trojan Mini Motor. I've just fitted the new main bearings and oil seals so at least it's starting to go back together. I need to get some new bolts for the cylinder head, as someone seems to have been heavy handed with them, they're pretty necked, and on an engine of that age they wouldn't have been stretch bolts. I also need to helicoil the thread for the spark plug as I stripped the old one with hand tightness! I also need to make a circlip for the gudgeon pin as I managed to lose one - D'Oh! I need to solder on a new HT lead on the the remaining stub of the old one and then maybe I'll be able to try running it with that lot done. After that I'll need to find/make the other parts that didn't come with it.
Edited by Matthew-TMM on Friday 10th August 01:24
Sounds like a cool project! Probably be better off buying a circlip, another motor factor job. If you still have one that is the same, treat it like gold, and take it to the motor factor for comparison. If you find the right size, buy three or four.
Edited by dilbert on Friday 10th August 01:33
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