Cylinder Head Query

[bcmc33]

As a pure matter of interest, what is the significance of the difference between these two cylinder heads?

This is my cylinder head with two holes ? one of which is blanked-off.

The second picture shows the picture of a head that was for sale on eBay last week ? this head did not have any holes. The with and without holes are confirmed by similar pictures in the Miles Wilkins book.

[ppnelan]

The end hole leads into the breather pipe 'chamber' and should be blanked off. It is probably only there to allow the chamber to be cast?
The inner hole is for the oil drain tube which lets oil to drain back down into the sump. Perhaps the eBay head is for a race engine with dry sump arrangement or external breather pipes?

No, I don't know...
But someone else will!

Matthew

[TeeJay]

As per Matthews comments; but I am sure Brian knows this; re the inner hole.

[bcmc33]

Yes Trevor, I'm well aware of what the holes are for - I was simply interested in knowing why and how there are heads that do not have either hole.

[rgh0]

I have one head that the rear most hole is not present on - not sure if its orginal or was welded up at some time. Maybe some versions did not have this hole and had the casting cores arranged differently.

All orginal heads had the front hole for the oil drain / breather as far as I am aware apart from the first few prototype heads that did not have the oil breather chamber in the head.

Looks like the Ebay head had the front hole weldup for some reason - maybe used on race engine with different breathing arrangements

cheers
Rohan

[JJDraper]

Any ideas for the cause of this problem? QED reckoned it was a liquid lunch on a Friday.... Caused no end of leaks until I bodged a solution.

Jeremy

[Dag-Henning]

We use to call the rubber tube "the oil drain tube", but very little oil drain from the head that way. It is a breather tube, and are often taken away on race engines, and the holes in the head and the block blanked off. A breather take-off from the cam cover to a catch tank does the breather job better . It is also a source for leakages........


Dag