Re: Engine Vacuum

[Angus Holliday <trstag@domain.elided>]

. Plugging the vacuum
>line solves the problem. Is the engine supposed to be air tight? 
No, the the Positive crankcase ventilation(PCV) system is designed to take
the gases that are in the crankcase and re-burn
them through a metered vacuum to the inlet system.  Older cars (pre-67,
earlier in California and some other cases) simply
dumped the crank gases out into the atmosphere.  This was usually done with
a downward facing pipe on the engine. 
PCV was the first real step in auto anti-pollution control.


Where does
>the air leak into the engine? Through the rings? Seals?
The crankcase pressure is primarily from leakage past the rings....some of
which is inevitable.  If you seal the crankcase by
blocking the valve cover you will usually blow the rear main seal out of the
main seal holder.  This will result in a goodly 
oil leak at the back of the engine into the bell housing.  Repair would
require the removal of the engine or trans (your choice)



 What's wrong with this
>picture? Any advice will be appreciated.
Since you are using a non-stock carb you will probably need to rig a PCV
valve and/or restrictor so that you get adequate CCV,
without excessive vacuum loss and consequent poor idle.  

Walter Holliday
Stag Specialists