John,
My 1275 was vented only to the atmosphere through the TC cover and I was
blowing a lot of oil out the scroll seal. Once I replaced the bad pistons
that were the source of backpressure and used Paul A's kit to restore the
scroll seal, the leak is gone. I'm still venting only to the atmosphere as
before, but have added a draft tube to the TC cannister vent that points
down to the road near the motor mount.
This indicates to me that excessive leakage out the scroll can be an
indicator that the motor has excessive backpressure that may hint at a
problem. Some say that the 1380s need additional venting, no personal
knowledge. Mine is only 30 over but is turbo boosted which eliminates
manifold vacuum as an option.
Regards,
Glen Byrns
'59 bugeye
'59 Morris Traveller (Winifred)
>
> What is the disadvantage to using manifold vacuum to vent the valve cover?
> Seems lots of cars, particularly so-called hopped up cars, vent to
> atmosphere.
>
> How come?
>
> My 1275 vents through the breather can on the timing chain cover and
> (I guess) through the oil cap orifices. Doesn't seem like a whole lot
> of venting. I've read about adding a crankcase vent at the unused
> mechanical fuel pump spot. Is that worthwhile? Also seems that a
> substantial vent in the valve cover would also help reduce pressures
> that push oil past the crankshaft scroll "seal."
>
> Comments?
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