On my '72 at least, the carb is supposed to suck in the fumes
from the valve cover as well as suck air from the carbon canister.
If there is too much gas being blown out of the valve cover, it will back up
into the carbon canister and eventually ruin it.
(This is a lousy design, BTW. Maybe there should be a check valve in
the hose to the canister to prevent the back flow.)
Maybe your carb is not sucking properly, or maybe it is not
hooked up at all. In this case, replacing the canister
will simply cause the new one to get ruined, too.
If you have no way to hook up a proper suction connection,
I would simply leave the valve cover vent open to the air.
Doug Braun
'72 Spit
At 04:13 PM 7/31/00 +0000, you wrote:
>I installed a Weber downdraft carb and upgraded the exhaust system on the spit
>and
>occasionally experience high pressure in the crankcase and valve cover. It is
>sufficient
>to blow oil out the dipstick and the hold down holes in the valve cover.
>
>With the hose removed from the carbon cannister it cures the above problem.
>The Cannister
>is 28 years old. Will a new cannister solve my problem or am I looking at a
>bigger
>problem than that will solve?
>
>Thanks for any help.
>
>Frank
>Drummond
>
>
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