At 09:11 AM 5/14/03 -0700, Bill McLeod wrote:
>.... If there is a pipe coming out the side of the engine which rises and
>then curves abruptly down toward the ground, you are already vented, and
>do NOT need to vent the valve cover. ....
There is more to it than that. An engine needs two vents, an inlet vent
and an outlet vent, and some means of making air move through the
crankcase. This is to purge and remove fumes, byproducts of combustion,
and condensation from the crankcase to keep this stuff from building up in
the oil (sludge) and coating the inside survaces of the engine (scum). To
this end you need both the valve cover vent (inlet) and the tappet cover
vent (outlet). Ideally the inlet air should be filtered (but it isn't always).
For a description of the "forced" ventilation of the MGA and early MGB
engines, see here: http://mgaguru.com/mgtech/engine/cv101.htm
Later MGB engines use intake manifold vacuum to force crankcase ventilation
and also to route the crankcase fumes into the intake manifold to be
burned rather than vented to atmosphere. When the sealed fuel system and
carbon canister are used to capture evaporated fuel, the same crankcase
vent system is used to purge the carbon canister when the engine is running.
For any of this to work you do have to have a crankcase inlet vent.
Barney Gaylord
1958 MGA with an attitude
http://MGAguru.com
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