Nowanker

Yep, it's losing water, and it appears to be going through the motor, not overboard. Still haven't actually confirmed that yet...
Professional opinion: (39+ yrs...)
The more precise your preliminary diagnosis is, the more efficient your repair will be.
With almost any repair, you'll be ahead of the game if you're capable of making an accurate diagnosis.
If not, just start rippin' sh*t apart and hope that the problem becomes evident along the way.
Just my $.02, free to disagree.

outhouse

Exactly.


As much fluid as he went though, it should have been evident if external.


Would never advise blindly looking, in this case removing heads is the exact call.

db2xpert

Thanks for all the suggestions.
The heads will be pulled when the engine is out of the car for rebuild.
Having two cyls on opposite banks down 40# and 50#, and two others down 35# and 20# -- says rings to me. While I haven't built any LS engines, I have built and raced dozens over the years.

Small piece I omitted before, there appears to some small oil hazing on the back of the car, pin sized droplets. Oil level in the sump was down about 1/2 qt from 4 days of events.
Everything to me implies head gasket for leak, and rings for the rest.
Car idles normally, and seems to run fine on track, just down a hair on power.

I mentioned before that my exhaust pipes were black, from "seemingly" running a bit rich. After every event.

Heads and block and liners will be thoroughly checked when it's apart.

I don't have time to do things piecemeal looking for the leak anymore.
Just going ahead with the rebuild to ensure piece of mind.
And a slight bump in power and reliability.

Thanks, again..

Will update after the teardown, a week or so.

Nowanker

Good luck with the rebuild, and hope the block checks out OK!