Well today I need to start my cam break in and other than worrying about my head gasket blowing up and timing cover leaking I need to figure out how to add my other gallon into the cooling system. How do I displace the air in the motor itself with coolant?

If it's not too much trouble, what I have done in the past is drill a small hole in the thermostat. It lets the air bleed through. Once you start the engine, leave the cap off for a few minutes and add water ass needed until full.

X2

Wouldnt that make my thermostat useless...

No the hole just lets trapped air out before the thermostat opens.
I drill two 1/8 holes at opposite ends-not much water flow through two 1/8 holes is there but it helps bleed air out tremendously

When air gets trapped in the cooling system, often the air is trapped inside the heater core. Jack the front of the car up slightly so that the radiator cap is significantly higher than the heater core when filling the system. Even with the small hole drilled in the thermostat, you will probably need to add more water/coolant once the thermostat opens fully. Always have plenty of water ready available when starting/running-in a new engine and keep an eye on the radiator level.

Alright I will probably end up doing that. One more question about the cooling system. Would it benefit to go ahead and add some of my last gallon of water into the intake manifold or go ahead and just wait for the air to get pushed out and add everything into the radiator.

When air gets trapped in the cooling system, often the air is trapped inside the heater core. Jack the front of the car up slightly so that the radiator cap is significantly higher than the heater core when filling the system. Even with the small hole drilled in the thermostat, you will probably need to add more water/coolant once the thermostat opens fully. Always have plenty of water ready available when starting/running-in a new engine and keep an eye on the radiator level.

So I can just leave the cap off the radiator? Wouldnt the coolant/water mix spill out?

Put the cap back on the radiator. Once the coolant begins to circulate (thermostat open) you can feel the heat of the coolant in the upper radiator hose. At this time open the radiator cap very, very carefully and check the level. Did I mention that you need to be very careful when removing the radiator cap . . . . ??!!

Just pull off the heater hose that attaches to the intake manifold. Then add coolant until comes out of that intake fitting. No need to drill holes in the thermostat.

Why not leave the cap off to let the system burp itself? You will see that coolant will need to be added onces it burps itself.

I normally just leave the rad. cap off, fire the engine, let it run and once the the stat opens and the level drops, add in however much you need, then let the stat open again. It's either going to go down some more or start flowing out. Either add more in, or cap it.

Just pull off the heater hose that attaches to the intake manifold. Then add coolant until comes out of that intake fitting. No need to drill holes in the thermostat.

however, drilling a hole in the thermostat takes less time and makes less mess.

however, drilling a hole in the thermostat takes less time and makes less mess.

I spend no time drilling a hole and pay attention to what I'm doing.

I spend no time drilling a hole and pay attention to what I'm doing.

I just got in the habit years ago of drilling a hole in the thermostat. It just makes it easier. No need to fill hose, or fill through the thermostat housing. Drill a small hole, fill everything up and start it. The air will bleed off and you can top it off once it warms up. Just makes it pretty trouble free.

Takes about 10 seconds to drill a tiny hole in a thermostat vs. dealing with unhooking a hose, carefully filling it and hooking it back up.

I just got in the habit years ago of drilling a hole in the thermostat. It just makes it easier. No need to fill hose, or fill through the thermostat housing. Drill a small hole, fill everything up and start it. The air will bleed off and you can top it off once it warms up. Just makes it pretty trouble free.

Takes about 10 seconds to drill a tiny hole in a thermostat vs. dealing with unhooking a hose, carefully filling it and hooking it back up.

Yep. And when building a high dollar car, I AM VERY careful about spilling ANYTHING....

Take the thermostat out, open the thermostat and put an asprin in it to keep it open. Reinstall it, and fill the system. Asprin will fall out and dissolve when thermostat fully opens.

We went thru a world of grief trying to burp my son's 383 Vortec engine. Two small holes in the thermostat and no more trouble. Honestly, how much water do you think you're going to force thru two toothpick size holes before the engine warms up? If you finally get it burped without the holes, count on doing it again if you ever have drain the radiator/system for any reason.

Alright well sounds like theres lots of ideas that would work. I pick one and go. But right now I need to get rid of my horrid oil belching problem because I cant even run the car safely and confidently to let it warm up at all.

I normally just leave the rad. cap off, fire the engine, let it run and once the the stat opens and the level drops, add in however much you need, then let the stat open again. It's either going to go down some more or start flowing out. Either add more in, or cap it.

Same here and never needed a hole in the stat.
In all my years of messing around with these old cars I can't remember ever having a problem with trapped air.
I do watch the coolant level for a couple of days however.

I think you only need a hole in the stat IF the bypass is plugged.

Never tried the hole trick, too lazy or did not think of it when I had the thermostat out.

I usually end up checking the coolant level and adding some after the next 2 or 4 running cycles. This has always done it, except for a Windstar 3.8 minivan, where the rad cap was lower than the engine. I had to have it explained before I figured it out, then just pulled a hose and it worked fine.

Good stuff here.

Here's what I tried this time.

Drilled T-stat, filled rad, then got the free Motorad cooling system tester loaner tool from A-zone. Pressurized the system to 15 psi. When I relieved pressue, you could hear the bubbles / air pockets coming through the cooant, and the level dropped a good 1/4-1/2 gallon or so. Filled rad again and repeated twice. I haven't started the car yet, but in my mind, I would think this would be a good "no mess" way of getting most of the air purged before starting.