7/8 " Cylinder head core plug

[Tattybogle]

The front core plug on my Ruby head was leaking, so I removed it and reached into my spares box for a replacement. To my surprise I found it is too small (3/4") and fairly rattles about in the 7/8" bore in my head. (The other plug in the head is 3/4" )

The Seven Workshop only list 3/4" for the cylinder head, so has anyone else come across this? It doesn't look as though the shoulder has been machined out to the larger size.

Ebay has yielded some 7/8" plugs to get me off the hook, but I wondered if anyone has come across this before?

Thanks!

[steve davidson]

I recently did one on the block and found that I had to go for a metric size to make it all work. Not sure about this smaller one on the head but it maybe that you need to go metric to make up for sins of the past.

[Tattybogle]

I recently did one on the block and found that I had to go for a metric size to make it all work.  Not sure about this smaller one on the head but it maybe that you need to go metric to make up for sins of the past.

Thanks Steve - that is a good idea.  I think I am sorted with a 7/8" plug but I shall follow up on your suggestion if it leaks!

[Austin Carr]

As 7/8" = 22.225mm, surely a perfect fit.