I don't understand where you are getting your numbers.
The "substantial presence test" is only used to determine if an alien (not a citizen or green card holder) is a US person for income taxes. As a US citizen, you owe the federal government a US tax return reporting all your worldwide income, no matter how many days you live overseas.
The "physical presence test" is used to determine if you qualify for the foreign earned income exclusion, and you must be physically overseas at least 330 days, not 183 days. Since you don't have foreign earned income, this is not relevant to you.
Basically, if your only income is a US pension, you must report it on a US tax return and pay US income tax on it, no matter where in the world you live and no matter how many days you live there. Whether or not you also owe income tax in the country where you are living overseas is not something we can advise you on.
There might be rules that apply to your Visa, we also can't help you on those.
