Ariel Owners Motorcycle Club

Just wanted to check, both my head and block have chamfered edges; I assumed these were mating surfaces. But when I place head onto block, I was expecting an interference fit, whereas in practice, I can slide the head about by approx. 1/8".
Is this correct?

Where are these chamfered edges? The seal is on the top of the spigot or the top of what would be a liner if there was one. There should be a small gap twixt the head and cylinder surfaces where the bolts go through. You may have a later cylinder and an early head. The diameter of the spigot was reduced in order to make room for a head gasket, which was not fitted until 1952. I don't have the different diameters to hand but it may have been discussed on here before, the difference would be about 1/8" on dia. In any case the fit was 'snug' not an interferance.

Hi Roger
I wish I had taken some pictures, but from memory: The liner is exposed above the top of the cylinder and has a slight chamfer on the outside edge.
I think the cylinder head has a slight internal chamfer.
As the seal is made at the top of the liner, the fact that I could move the head around on top of the liner I am hoping is not going to be an issue.
Fingers crossed!

When you drop the head onto the barrel, without the pushrod tubes, pushrod or headbolts in, then it will sit on the raised spigot. You can rotate it 360 degrees- which you need in order to grind the joint to an airtight seal.

With the situation Roger describes the head without bolts in will move a considerable distance laterally. Flopping around like that is not likely to produce the best lapping of the two surfaces without if being positively located by the spigot.. The bolts will still locate it but the thin spigot is not supported properly by the head. The ideal situation is lap both surfaces at the same time and then clean and oil off the inner one and keep lapping the outer surface for a little while . This is extremely satisfactory for iron head and barrel OHV motors. Nev

Hello Steve,
you probably have a NH cylinder and a WNG (or NG) head.
see pictures.
NH cylinder has a 'thinner' liner / rim




WNG Cylinder with WNG head :

NH cylinder with WNG head :

as you can see the NH cylinder has larger finning

I looked up your introduction post with the pictures from your WNG and you indeed have a later cylinder

Hi All
Big thanks for all your very helpful responses.
I have found a picture from the previous owner of the top of the cylinder.
The mismatch between parts/models is concerning me, so maybe I can ask for your help with the following:
1) Does it matter, at a functional level, that the cylinder/head are from different models?
2) Does it change the advice from Nev regarding lapping?
3) Is Wellseal an alternative to lapping?
4) Purely down to authenticity only, what are the chances of being able to find a NG cylinder?
5) I assume I must also have a NH piston?

Hello Steve, your picture does not show the cylinder that is on your WNG right now.
it is a earlier one, WNG or NG.

But that aside, I think you can use the cylinder you have now, it did function before.
Give it a lap and if you really, really want it to look like a WNG cylinder you could take out the angle grinder and slim down the outside

Hi Vincent
I am very sure it is my cylinder - Ron sold me the bike and it is his picture.
What makes you think otherwise?