Originally Posted by
Lumps
Also, if it was such a problem with this engine why don't Chieftans etc also have wet heads, the article seems to indicate not.
Nobody seems to have responded to this particular part of your question, so I'll have a shot at it:
The TLS engine is unlike the Navajo engine, the TLS engine is a "parallel valve" engine, and the Navajo engine is an "Angle valve" engine. The parallel valve engines are much lighter, and have significantly different cylinder heads. The angle valve cylinder heads have better cooling at the valves; the valve guides are longer (more transfer area) the valves are further apart so have more mass between them to transfer heat, and have greater cooling fin area. So, with a different head construction, different compression ratios and different operating parameters, it doesn't follow that the Navajo engine should need oil cooled valve guides like the TLS engine does.