Dar< Davis has been making conversion heads for at last 30 years, He recomends the larger prop loads and the engines thus produce
more thrust at a lower rpm. Also they run cooler than glow, if running hot they are overcompressed (pre-ignition) which will take its toll
on any engine glow or diesel. The fuel formula with the kero is also has more of a lubricant action, As far as made as diesels I believe
on the MVVS 12,15,and 61 the only variance is the diesel head and a smaller bore carb. The Irvine Q40 and Irvine diesel are the same engine except for the head. In enya the CX11, CX15 and 25 are the same except for the head (the 25 does have a restrictor in the carb
barrel).It also follows that an engine will last longer at 9 or 10K rather than 14K. There are a few engines out there that may have weak
cranks or rods that might not make a good conversion but also how long do they last as glow?. My case in point at least as far as MVVS
and Enya (and only the one irvine as far as I know) they are factory issues the only difference being the head martin
One more thing the MVVS 40 and 49 make super conversions massive rods, I have the 40 with the davis head, my only regret was not getting the 49 instead, and back to the orginal issue the LA 40 and 46 are good inexpensive glow engine but really turn on as diesels