well if allowed to go long enough i suppose the coolant level could get low enough to somehow get a bubble into the head/s in the right spot to cause a overheat issue and could cause a weak headgasket to fail. alot of couldoves there

 

No need for an air bubble. If you're low on coolant the car can easily overheat.

 

with the lt1 it only takes a bubble in the right place.

 

On an old school car removing the overflow will not hurt anything. Once the car reaches hot soak it pretty much has all the coolant it needs, hot. The main reason for the return system is humans. They see the radiator "low" when its cold and they add coolant. That coolant ends up on the ground. Coolant is very bad for the environment. Without the coolant overflow an old school system will regulate itself. This is not because of the tempters the system run at. Anyone who owned a big block stuck in a traffic jam in the 70's knows how hot they can get. The only what the system would need coolant add would be if there was something wrong with the car and it got a good 20 degs hotter then what it considered "normal" hot soak.

As a general rule on old school cars the highest point in the coolant system is the top of the radiator. This is why the system does need bled. Since the highest point in the system is the radiator cap that is where air ends up. LT1's needs to be bleed. So if the system goes low every time the car cools down it could trap air in the system. The trapped air can cause a blown head gasket.

 

Why don't you let us know how high the coolant pressure go's with the overflow tube blocked.

 

https://camaroforums.com/forum/membe...3-94-15717.jpgThe Camaro's heater lines leave the heater and drop down to the frame, then one line go's up to the water pump. The other returns at lower location back to the water pump.This means that there will be trapped air in the heater core.
You'll need to remove the heater core cover inside the car and tap the heater core with a soft rubber mallet to get the air out, with the engine off. Then with the engine on and hot you can tell if there's air trapped in the heater core by feeling for cold areas in the core. When there's no more cold areas the trapped air is out and then use the heater air bleed valve to remove the air. If this dose not work you may have a clogged heater core.
The v8 cars are a pain to bleed all the air out but it must be done.

 

I usually just turn the heat on.

 

what would tapping with a rubber mallet do? does the air bubble get stuck to the side of the heater core and you have to knock it loose? There's a procedure for bleeding the coolant lines on shbox.com and it works great, no need for a mallet.