[Hib Halverson]

I still keep touch with some of the guys I met from Lotus and MerCruiser back in the "old days", and I emailed one of them yesterday.

He told me during development they figured exhaust pressure would keep the oil off the stems when the engine with running but they did not figure on engines with some miles on them starting to leak down the exhaust stems when the engine is stopped. That's why for 91, they added stem seals.

He made the point that when the engines were new or near-new, even without exhaust valve stem seals, they wouldn't puff oil smoke after cold starts. When he said that "engines with some miles on them" didn't necessarily mean "worn" but that worn engines would have a worse problem with that.