General question for Detroit 2 strokers

[dtcerrato]

Why are some Detroit 2 stroke's valve covers vented & some are not?

[luvrbus]

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  

[Geoff]

The turbo engines need more breathers than the non- turbo engines. 

--Geoff

[dtcerrato]

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.

[luvrbus]

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    

[dtcerrato]

Thanks for the responses