Captain America appeared in Tales of Suspense #58 (October 1964) with Iron Man, and became the co-star of Tales of Suspense until after Tales of Suspense #99, when Iron man spun off to his own title, and Tales of Suspense changed its name to Captain America with issue #100. Captain America starting with issue #100 also allowed fans to avoid any confusion as to what issue numbers were referenced; the older Captain America series from Timely never reached three digits.
I have profiled only the Captain America stories of his run in Tales of Suspense - I'll leave the Iron Man stories for someone else. Many of the entries below have no cover - I gratefully accept scans!