we had an entry way widened a bit which required them to install a longer support beam. I'm absolutely not a professional. But the 2x4's supporting the larger beam don't seem very substantial to me. There's just one under each end of the cross beam.
For an 8.5' span I'd say no. The purpose of the jack studs isn't just to hold up the header - it also helps distribute the load more evenly to the foundation. For that wide of a span the IRC calls for 2 jacks(see R502.5 Allowable girder spans).