When we were building the 230 and got to the rods, my macinist recommended leaving the squirt hole open. The holes squirt oil on the thrust side of the cylinder walls. He (machinist) seemed to think this was more beneficial that eliminating them. So we did not close the holes.
The only problem in dealing with flatties is the external heat. The water temp. will remain at a comstant level but the external temp. is higher than I like. The transfer of this external heat to the oil is of concern to me. Starting research and work on a 308 flattie. The external heat issue is to be addressed more fully. Hope this helps.
