Cylinder heads

[tamson]

Hi, I recently posted about a snapped exhaust valve, it had somehow broken off just above the grooves for the keepers. So I've ended up stripping both heads as an exhaust stud needs helicoiling on the other head and I thought while I've got the engine in bits I should get it sorted. I decided to do some research into the heads that I have, turns out left side is p/no 029 101 371B which is a 79 late bay with square exhaust ports, right side is 022 101 372G which is 76-78 with oval ports. Is it unusual to have miss matching heads and does it matter that they are not t25 heads? I have read some conflicting info regarding the t25 heads, some sources state they take 37.5 intake valves and others that say they take 39.3. Lastly are these heads symmetrical, in other words does each head have a specific part number that denotes left and right? Thanks

[bigherb]

Well any thing can happen to these engine in the hands of bodgers.
All CU engines have 39.3mm inlet valves.
Are heads handed? Yes and no. European head are generally interchangeable, fuel injection heads where handed when the engine was build due to one head having a mounting for the cylinder head temperature sender, replacement heads where interchangeable coming with the sender mounting.
Some USA heads are handed due to one having an EGR port.
The problem is also some heads have a different sized combustion space due to some heads using a spacer ring between the head and barrel.

[tamson]

So do the CU heads differ much besides exhaust ports and intake valves, I didn't seem to have any running problems but perhaps engine wasn't working to full potential. I wonder if I would be better investing my time and money into finding a set of appropriate heads for my engine code.

[bigherb]

So do the CU heads differ much besides exhaust ports and intake valves, I didn't seem to have any running problems but perhaps engine wasn't working to full potential. I wonder if I would be better investing my time and money into finding a set of appropriate heads for my engine code.

Apart from the ports and valves the CU heads have a better head to barrel seal not requiring the sealing ring of earlier heads.