Coolant leak

[ydrogs at gmail.com (Gordy Stedman)]

My 79 has a bad coolant leak.  After 20-30 minutes of driving I end up with
about 1/2 of my radiator coolant missing.  I filled it back up and burped it
this weekend and idled the car for 10 minutes through 2 radiator fan cycles
and the coolant level was down appoximately an inch.  I park it inside and
have never seen any puddles under the car and when driving there is no steam
or over flow from the radiator.  Also no puddles or even wet carpet inside
of car so I assume the heater core is not leaking.  Just put a brand new
radiator in with a new cap and the system does not have an overflow bottle.
3A engine with JH head.  I thought it might be a blown head gasket but got
160-180psi across cylinders.  I did notice the exhaust having a white tint
to it so I think the engine might be burning the water but with such good
cylinder pressure I do not think there would be a way for water to get into
the cylinders.  I did find some milky white oil/water mix on the inside top
of the valve cover but no water in the oil when drained which also made me
think the head gasket was blown.  The engine starts up just fine and idles
good and revs ok but have noticed a small decrease in the butt dyno.  I am
not trying to track down a small or gradual leak but a constant massive loss
of coolant.  Any thoughts before I go insane?  TIA.

-- 
Gordy
MK1 x 4