I wasn't sure if it was a coolant or oil passage that concerned me, so I grabbed a DOHC head and put a SOHC head gasket on it - you can see that with the exception of some of the SOHC oil return holes between the bores, everything appears to line up:

It looks like the holes I was concerned about are water passages, not oil - if you look toward the right edge of the head, there are small passages that appear to go up above the combustion chamber and you can see that they're blocked by the SOHC gasket.... perhaps they would work if DOHC gaskets were used:

Here's a better picture of the small passage:

The small holes seem to be connected to the same chamber as this flange opening at the rear of the head:

Also, note the triangular/tear drop shaped insert that is fastened with a screw - the SOHC head also has one of these, but IIRC, it's at a different location. I don't know what purpose it serves - perhaps a plug of some type:


I've kept these DOHC heads to try to learn more about them after I finish my current project. About all I know so far is the twin cams and sprockets make them nearly twice as heavy as the SOHC head. <img src="/forums/images/graemlins/scared.gif" alt="" />

I wouldn't want to put these on a 12v SOHC engine until I knew a lot more - also, there's no distributor provision, so the ignition system, ECU and harness would have to be changed.

Frank