Flat tops are good, it’s just how you use them. Brad has a few words on them worth having a look at.
Well that’s looks like a basically stupid idea. Let’s get a perfect good crank lubrication system and then bleed off oil pressure. Madness. I thought the idea is to get film of oil evenly across the bearing surface by yamming in though the middle and out the periphery. Apparently somebody thought otherwise. Only time you see holes in shells is for oil feed in like on mains.
However, I do remember something about higher pressure oil pumps being brought in somewhere around the ST intro time, and a bit fuzzy, but other models may have rods with centre oil feed to the little end. They also introduced tea spout theory to oil ports try to get better flow. Oil pressure switch was the giveaway when they changed over.
Sp5’s SP4S had barrel rollers for mains. Steve R and I have had played with them. That was a short term thing. There was fair bit of let’s try this, is my take on it. The factory has a long history of letting the consumer find design faults. The numbers of 1098 and 1198 engines that were no questions asked warranty swaps was quite large. Bearing preloads got heavier, and the water jacket wall got eaten away and blew coolant into the exhaust because of standard coolant and cavitation on a bend, it was if they knew it might not go well. After a few engine swaps at the shop, bottles of “Special” coolant turned up that seemed to fix the issue. I think they dropped off some preload or changed bearings, not sure. Shop went bankrupt and closed shortly after the 1198.
