Gordon Shumway wrote:
On Wed, 15 Feb 2017 23:44:03 GMT, Mike
m wrote:

I want to expand a door opening from 3' -6'. What size of lumber
and beam type do I need to use to create the beam. It is a bearing
wall in the basement.

Consult an architectural engineer.

There are online calculators for that . The one I used recommended doubled
2x10's with a 1/2" ply between for a span of 10 feet between supports for my
main floor beams . So I supported them every 8 feet ... my floors don't
"bounce" . I expect that would also be suitable for the OP's header .
To the OP - you will need to support the floor joists on BOTH sides of the
wall while you modify the opening since it is a load wall for the structure
above .
--
Snag