Ariel Owners Motorcycle Club

By comparing the two cylinders on the picture that I posted you see that the larger finned cylinder has a flat circle around the liner.
that is where the gasket should be, the one Roger mentioned.
(the gasket goes around the protruding liner, not on top of it).
But ofcourse I could be mistaken and there is a model in between the WNG one and the later NH one.

I followed david Anderson's advice, when I had issues lapping a 500 iron head (the head would have needed a lot of lapping to get it onto spigot - likely due to mismatched parts from different places ) and made up a copper gasket to sit on the spigot. Seems to work

To check which barrel you have count the fins (on the barrel) - the later 'big-fin' one has an additional fin at the bottom, so 10 fins in all versus 9 fins for the earlier type barrel.

The later ('52-'55) 350 used a copper head gasket on the lower joint (ie not on the spigot), might be worth trying one of those if you've got the later barrel.

HTH

SG

So far as I know (and I was Singles Spares Organiser for 7 years) there are only the 2 cylinder types between 1933 and 1955 which are shown in Vincent's earlier photo. But there may well have been several suppliers of cylinders, not to mention quite a number of cylinder patterns, which may well lead to cylinders of the same type having different appearances. The critical difference is the shape of the mating face with the head. The circular one is 1952 onwards while the H shaped one (with 2 horizontal bars) is up to 1951. Incidentally, the later cylinder is slightly shorter than the earlier one so if you can persuade an early head to seal on a later cylinder you get a higher compression ratio.

Thanks for clarifying the differences Simon. I have 9 fins so without doubt an earlier NG cylinder.

I’ll run the engine in the next day or so - soon know if there is a seal problem!

Very good, looks like it will be o.k. now.

So, I lapped the joint as suggested, however, there is still a very small escape of oil/carbon, between the head and the barrel. The pictures show the head/barrel (before lapping). As you can see, on the bottom of the picture, which is actually the front of the engine, there is some corrosion on the head, but I don't think this is a problem as the seal is not made there, but it is where the leak is.
Is it normal to have a tiny leak?
Any other suggestions?

Thank you

Steve

It rather looks as if the spigot on the barrel still isn't making a good seal in the head,
especially by the pushrod tubes.

With the head sitting on the barrel there should be a noticeable gap between the
surfaces where the head bolts pass through. If there isn't this may be why the
spigot won't seal.

Do you mean when the head is tightened down Will?

With the head just sitting on the barrel - no bolts and no pushrods or pushrod tubes.