Hey guys I recently purchased a SBC 350 after it sat for a year. I did an oil change and cleaned out the sump as well since it had some water in the oil either from sitting or a blown head gasket I am not sure. The engine runs find and I have about 130PSI on each cylinder... I'm new to this and did not run the test right I did not remove all plugs or hold the throttle wide open so it may be potentially higher. I will re do the compression test soon ! This is my current issue please let me know if you guys have any ideas. Brown water, surging in heat exchanger and a sketchy setup. The video shows the issues better

Here is the video:

I wouldn't put the motor in anything until its been over hauled. The 130 psi is low, and may increase (150) if plugs pulled and WOT but I wouldn't put a high wager on it.

Black brown water is rust. No antifreeze in closed cooling means there is a problem. Rebuild time.
sorry!.

Well the engine did sit for about a year and I am not sure what they used for coolant. I'm from the Caribbean as well so we never have temps dropping below 20C so I can rule improper winter storage out.

I couldn't tell if there were bubbles in it or was the water just surging up and down because you were cracking the throttle and there is no thermostat in it. Regardless the engine is full of rust and will probably be constant problems. JMO

Head gasket if those are bubbles... looks like instead of antifreeze someone ran water in the engine...
another worst case is the heat exchanger is bad which allowed salt water in the engine...
130 psi equal across all cylinders isn't that bad at all -- that wouldn't worry me if it was a stock marine engine...
just some thoughts to check...