Steam Radiator Not Heating Up

pics of the piping beneath the radiator, the radiator itself and pics of the main vent you replaced

And... how big is that copper pipe? If it's too small the radiator can't possibly get enough steam.

I'm not a pro, but perhaps condensation is filling that copper before steam can reach the rad? how far does that copper run from where it's connected ?

From the looks of your seventh and eighth pictures in the second set, the pipe past that shut-off valve looks reduced and pitched the wrong way, allowing water to pool in that area, and the radiator looks too level and not pitched towards the supply pipe. Also, turn that radiator vent vertical. That can affect its ability to open and close.
Also, I can't tell from the rest of the piping but this looks like a counterflow system. looks like there may be a couple locations on the mains where they piping has been reduced and may also allow water to pool.
The vent in the 7th and 8th picture looks like it is leaking (based on the staining on the wood above it.
We don't like copper on mains and above the water line but it is what it is.
Finally it looks like the header, above the boiler is not as high as it should be (24 to 28 inches minimum). That will cause wet steam.

You need to have someone drill and tap the radiator vent opening for a 1/4" hole and then use a 1/4" to 1/8" bushing in that newly tapped hole so that the vent is no longer loose. A loose vent can some day blow out of the hole and then you have a risk of scalding yourself or creating a wet mess when you are not home.
1 degree is not much pitch. How did you determine the 1 degree? Ideally, if that radiator could be pitched about a 1/4" from the vent end to the supply pipe end, it should be fine.
Pipes should be pitched about a quarter inch per 10 feet. more does not hurt anything.
A counter flow system is where the mains start out at thier lowest point, at the boiler ( pitched down towards the boiler (with appropriate drips near the boiler for condensate to drop to a short wet return at the boiler). Condensate then runs in the opposite direction to the steam going out from the boiler. Steam out from the boiler, condensate in the same pipe running back to the boiler.
In a parallel flow system, the mains start out at their highest point above the boiler and pitch downward from there so that both the steam and the condensate flow in the same direction and the condensate continues to run into a dry return, after the last radiator run-out off of the main. That dry return may continue in a loop around the basement and then drop down to a wet return before it gets back to the boiler or the return pipe may drop down to a wet return right after the last radiator run out and the wet return will run back to the boiler, below the boiler's water level.

The threads on that vent should be tapered. You might be able to tighten up the connection just by turning in the vent a few turns.

Here is what I would try. Remove the radiator vent. Start the boiler. If steam gets to the radiator, then turn off boiler. The problem is likely the radiator vent. If no steam gets to radiator, then the problem is likely in the piping.

I'm not sure if I'd trust a phone app to accurately measure 1 deg slope.

For the record a true 1° should be plenty. 1/4" per foot slope is 1.1934894° so you are almost at that with 1°. The pipe slope for counterflow steam is 1" in 10' which is only .4774538°. I know 1° doesn't sound like much, but it should be fine.

lula1121 said:

When i turn the air valve on the radiator it will get tight but the valve will be facing down and I know it is suppose to be facing up. Any ideas with that?

Add some teflon tape. It doesn't need to hold more than 2-3 psi at the most, usually less. You can try using a tap to clean out the threads a bit if it's not taking more than 4-5 turns.