are the head&block surface,s the right ra for the cometic gasgets,they need to be really smooth,i have seen that be a problem.

There RHS heads. I'm only seeing @ 8.5 lbs of Boost at WOT. I'm running FelPro MLS head gaskets

Check the angle of the intake flange of the heads against the angle of the sealing surface of the intake. If those angles vary by more than a degree or two, then it can cause a leak. If the heads were milled and weren't perfectly flat or the intake was machined incorrectly then those angles can vary.
Eddie

I have been wondering that, but would I not see some sign of moisture on the intake gasket around the water ports?? They were dry. Seems like most of the milk shake is up front by the deck.

on a drag car engine once i had a smililar problem.. was a 400 small chevy at a very early point in its like it developed a cracked cylinder wall.. on the side closer to the intake.. if you left water in the radiator over night it would milk the oil.. if you ran the car all day it wouldnt.. i thought it was due to having mls headgaskets and a rough deck figured they was leaking.. so i just dealt with it for 2 years always drained the radiator after use.. always compression checked fine threw out the years.. ended up taking the engine apart for other reasons and i happened to see the hairline crack.. it went for 2 years like that .. just a thought..

Do the head bolts go into the water jackets????? They do on some BBC Gen engines and you need to use sealer on the head bolts.

i'm not sure i understand.... he starts off by saying

" everything was fine until i changed the prop"

so why would this motor have fundemental and basic machining or configuration errors suddenly ?

i think this has more to do with the extra 1000 revs on a motor that may or may not have had 6000 rpm in mind when it was thought out.

i think the heads have to come off and fix the headgasket that failed for whatever reason at 6k...

and then if this motor is now going to run 6 k all the time, then configure it structurally to do that. high clamp load hardware on the heads etc...

why doesn't he change the prop back?

The motor was built to run 7000 but I'm not running it that high cause I don't want to run the fuel or the boost. The prop on there was to big. it was for the last 600 cube plus motor..I propped down to get into my power band and runs great. I'm running ARP studs in the heads so that shouldn't be an issue. I don't think it's the head gasket. I'm running Fel Pro MLS gaskets and they should have no problem holding that amount of boost. As far as putting the old prop on..I think that is just putting a bandaid on the problem..but have thought of it. The boat runs GREAT..I would have never known I had a problem if it wasn't for the milk shake out the breathers.
I really want to fix this myself instead of kicking it to a shop..as that would cut into my beer fund.

you need to rule out the head gaskets.
if they are fine then you need to die the heads.
If that checks then seal, heat, and pressure the heads.

I am confident you will find the leak in these steps.

good luck