Ok here goes. The motor is a .030 over '70 318. I suspect that the motor was rebuilt sometime in the 80s judging by all of the orange silicone. It didn't seem to burn much oil before we tore it down but we did not drive it much.

New Comp cam, timing chain and oil pump. Scuffed the cylinders with red scotch brite and called the short block good. We picked up some JY 714 closed chamber swirl port heads from a '91 pickup. These heads were the transition ones before the Magnum and have rocker shaft oiling. I had a valve job done along with the correct springs for the cam. Edelbrock performer with a 1405 600 cfm carb. Felpro head and intake manifold gaskets.

The motor has been assembled for about a month.

During the cam break in I had one son in the car and the other one holding a flashlight to look for problems. At about the 7 minute point the lookout saw something bubbling at the rear PS exhaust manifold. I knew that we had exhaust leaks so I gave him a socket to tighten the nut on the stud. I looked again and realized that it was something coming out of the valve cover. I only glued the cork gaskets to the underside of the valve cover. I looked around some more and realized that it was water and that some was coming from the front of the valve cover as well. This is the valve cover with the PCV. I then had my son shut the motor down and it was at the 10 minute point. I had an old Prestone funnel in the radiator neck and the water was more or less "boiling" and not really flowing like I would expect. When the engine was shut down it pretty much erupted out of the radiator.

The underside of the valve covers and and different points on the rockers show evidence of water. After sitting 4 hours, the dipstick looks like it is just the Brad Penn that we were running. No water. We still need to drain some out to see if there is water in the bottom of the pan. The dipstick level seems normal.

I rented a tool to pressurize the cooling system to about 14 pounds and it never really bled down much.

This is the transition head from LA to Magnum and I ran an LA Felpro head gasket. The motor had a Felpro in it before and the new gasket seemed to match the old one.

Pressurized coolant during an engine run usually means a head gasket or a crack in the head I would imagine.

Opinions?

If that stat was in it might be stuck closed or partly closed. It's pretty well holding cooling system psi but it might be possible for combustion much higher pressures to be bleeding over 1 way into the cooling system. As said head gasket would be a likely suspect. what I would do is go to an emissions testing station & have them stick the probe in the air above the radiator coolant level just below the rad cap & it'll pickup any hydrocarbons if there is combustion gasses present and there is the blok check fluid that turns blue if combustion gasses are present (suck some air above the coolant up in an antifreeze tester with the balls in it with some of that blue fluid in there). I'd confirm/deny combustion gasses present or not & you've pumped it up to 15 lbs (how long did it hold and how far did it drop) then tear it down. EDIT your timing was not way retarded?/fan was functioning I'm assuming. On second thought a stuck or partly stuck stat would not show water under the valve cover. Might actually be an intake coolant port leak, they can be troublesome especially if the front cork gasket is a bit too tall for your head gasket/head/deck final "height" and it dont let the 2 front intake/head coolant ports/passages seal up tight enough

Did you put sealant on the end bolts of the headders? Pretty sure they go into the water jacket.

I also suspect stat problems.

Some SB's can have wet head bolt holes - they break into a water jacket. Pretty rare but some factory literature recommended sealant on the head bolts just as sealant is required on some manifold bolts. MA covered this in an article a couple of years ago. Of course it could be a cracked head or maybe gasket issue (maybe even the intake? not sure on a SB). Those are all the things I can think of that would put coolant under the VC.

I don't have headers on it and there are studs in the front and rear manifold bolt holes. Aren't those the only 2 holes per head that go to water in a 318 ?

I could pull the stat and do another run, but it won't be until this Friday. I don't have a temp gauge. I was using a heat gun liberally while the engine was running and the stat housing was right at 180 degrees. Get a gauge, I know.

I have a USED aluminum Eddy performer intake. The one that is basically an aluminum version of the factory cast iron 4 bbl intake. It has Felpro gaskets with Gaskacinch type stuff on it and I didn't use the cork gaskets on the ends. I used sealer on the ends instead so that the manifold would get a good seal to the heads.

I had turned the motor and distributor to fire at about 15 BTDC before we actually cranked it. The vacuum advance was plugged and I set total to 35 with a dial back light while the engine was running at about 2500 rpm. It fired right off and total was really close.

edit: I didn't use sealant on the head bolts. After a quick look at the FSM it doesn't say anything about doing that.

Stuck stat as stated but many exhaust bolts on that year 318 go in to water jacket Good possibility you also had a air pocket driving things every where coolant wise. By the way don't stick to that 36 total give the engine what it needs but watch the initial timing you don't want it over 25 degrees if possible. Pressure tester held for more then 5 minutes go and run and see what happens just don't fry it

timing is in the ballpark (I would go to ~42 or so since you ain't on the can). intake gasketing with no end seals sounds OK (& it did hold (psi). As said the corner ex studs holes (only) are wet & reportedly some head bolt holes are. I'm thinking the geyser is from a head gasket if the stat is open & I'm thinking it likely was (did you say the coolant was flowing early on?). 180 temp is fine but I'd think a combustion leak would kick that up higher than that (boiling at least) or maybe the combustion leak is just kicking it out but I'm missing something. Just thinking out loud till my coffee is ready. keep us updated

May try it again without a stat in and check the stat that I have. I should have at least stuck a thermometer into the rad neck.

I have seen a little debate about head bolts going into water. Most of time the posters say that the head bolts are dry and do not have water. That's was what I always thought was the case. This is a 1970 block.

I will have my son pull the exhaust bolts to check for water. I kinda think that they will be dry, though.

Thanks everyone.

Check the valve cover bolts, I understand they can get into water when one too long is used and it cracks the casting when being tightened, or if the hole is drilled to deep. I might be thinking B/RB though.

The head bolts are not supposed to go into water. But as was stated in the post above, either because of a faulty casting or an incorrect machining step, it is possible.

There is no way that the exhaust manifold bolts could get water inside the valve cover. That one is a dead end. Really, people!

Timing, you are close enough. There is no need to change what you set. Period. How could that have anything to do with the problem?

Thermostat? If it's stuck closed the engine will overheat in a few minutes.

The kit for combustion gases in the coolant is around $30 if you shop. Lisle 75500 I'd rather buy a reusable tool than another pair of head gaskets. I still don't see how a crack to combustion would result in water under the valve covers.

So we're down to leak from the intake or past the head bolts. Check those right after the combustion gases test.

R.

Don't use replacement type steel intake gaskets with an aluminum intake. Use composite type gaskets only, such as the Superformance gaskets, or from Mancini,Summit etc. and don't use the end gaskets. I don't think you have water coming out of the valve covers or your oil pan would be full of water. You are probably getting a spray out of the intake and running around the valve covers.

Felpro intake manifold gaskets with with Gaskacich and Permatex ultra silver on the ends. Water drops inside of the valve cover.

Ok, I finally got back to the motor. There was NO oil in the bottom of the pan, so I took out the thermostat and finished the cam break-in for another 10 minutes. The 190 thermostat WAS opening fine in boiling water as well.

After that I set the initial timing, we shut down the motor and started looking closer for coolant in the motor.

I pulled the PS valve cover and it looked like we had coolant. A camera down into the lifter valley showed what looked like coolant. I pulled the intake and found this. There was actually green coolant in the upper bolt hole for the timing chain cover and a little coolant pooled by the #1 lifters. There is a little pooled between the lifters for #2 and #4 as well.

When I pulled the intake, I saw a little bit of water run down the inside of the block to where coolant is pooled at the #1 lifters.

There was actually some coolant in the upper bolt hole for the timing chain cover. The screwdriver is pointing to the bolt hole.

I have an old Edelbrock intake and the mating surface to the head seems true with a straight edge laid against it. The intake manifold gasket appeared to form a good seal between the head and intake.

I don't know if the heads are cracked or if I'm not getting a good seal at the front of the heads to the intake and it's allowing coolant into the block.

NO white smoke, or any smoke, out of the tail pipes.

Ideas?

some of the t cover/wp bolt holes are wet & the bolts need viscous sealant on the threads. leak in 2 front head to intake big cooling holes.

Robert,

I didn't think that the top bolts of a SB timing chain cover were a problem since they came into the block and into "oil". I do have TPFE paste on the the other, lower, bolts since they clearly go into water.

Alright sounds like that ain't it, that you have that area properly taken care of

I pulled the intake and resealed the ports where the coolant goes from the heads to the intake with some Ultra Black.

No more water in the valve covers.

Thanks for all of your input.

that is good to hear that you got it & fast, coolant leaks are the worst!