Why are some Detroit 2 stroke's valve covers vented & some are not?
Because they don't have the governor, block or vent at the rear of the engine like used for the non vented valve covers , all the later engines were all vented at the valve covers since the 70's older 6L-71's could be vented on the side of the block or the governor housing or both.When I have the covers I vent from the valve covers on rebuilds of a 6L-71
The turbo engines need more breathers than the non- turbo engines.
--Geoff
When a fellow busnut's 671 Detroit na engine's valve cover vent was abandoned & capped off it caused LOTS of oil to mist out of the block vent on the back side of the engine. Don't know if he has a governor vent or not. That is why I asked the question.
Quote from: dtcerrato on May 13, 2017, 01:59:55 PM
When a fellow busnut's 671 Detroit na engine's valve cover vent was abandoned & capped off it caused LOTS of oil to mist out of the block vent on the back side of the engine. Don't know if he has a governor vent or not. That is why I asked the question.
That is usually caused by the blower gasket leaking at the mounting on the side of the block,no venting or a blown end plate gasket causing to much crankcase pressure,interesting ;D
Thanks for the responses