Cylinder head covers

Hi Guys,
I have seen a number of GT40s where the filler/breather holes in the cyl head covers of the 302W have been closed off with maybe just a pipe going somewhere (to get more clearance for the rear clip ???) Surely you still need some form of breathing? where does this pipe go? and how do you top up the engine oil ? down this small pipe??
cheers
Dave

 

[Bill Bayard]

Dave,

My GT40 (DRB) has a 351W, which is about 1/2"
taller than a 302. My breather/oil fill plug
has about 1/32" clearance to the rear clip.
The plug is over 2" high. Lower profile plugs
are readily available, so clearance for a 302 shouldn't be a problem.


Bill

 

[Paul Bearman]

The pipes you mention usually go to an oil catch tank mounted to the side of the gear box,perhaps someone can give us the technical reasons why this is a better idea rather than returning the oil to the Carb.

 

Why have a breather catch tank?.....

Putting oil in the carb means oil being burned, and passing out through the exhaust, and I suspect that the reason is the racing regulations guys don't like it... and its probably not very good for the carb either....

Anyone have a more likely answer?

Neil

 

Burning oil is very bad for the fuel octane number: if you get 5% oil for example, in the mixture, the octane drops by5%. A high compression motor might ping immediately.
So regulating the oil into the inlet system can be v important.
Another point is that many breathers into the carb work at high manifold vacuum, and so can assist is fouling plugs.
A much nicer solution is an evacuated sump system: this cuts oil use dramatically, and means head breathers need to be sealed..
However, many authorities frown on a direct line from the sump into the exhaust system ( if that is the method used).
Many race regs require a certain sized catch tank, and so it might as well be used if that is the case.
If you are concerned about emmissions, well the whole plumbing thing needs to run through charcoal cannisters etc etc
Rob