Reel to Reel tape decks have 2 speeds, 3.75 and 7.5 ips, normally switchable.
If yours only records/plays at the standard 3.75ips speed then no you can't adjust it.
I have a 4 track mono/stereo tape deck that records/plays at both speeds.
If your tapes are not "personal" I would be willing to transfer them to CD for you. Just send me the tape and blank CDs and some stamps to cover the postage back to you.
email me via the envelope.