That can be a fairly broad range of delay time. You'll often see 'slapback' echo listed between 75-250 ms. More recently, it may be a relatively short single repeat sync'ed to tempo (1/16 or 1/8). Little or no feedback / regeneration.
If you're going for historical accuracy (generated by a tape recorder), you might want to do the math on inches-per-second (IPS). If the distance between the record head and the playback head was 2 inches, then 2 in. / 15 IPS = 133 ms., or 2 in. / 7.5 IPS = 266 ms. Similarly, a 4 inch distance from record to playback would be twice as long for a common IPS [3-3/4; 7-1/2; 15; 30].
In any case, you might want to start with a VintageDelay or TapeEcho algorithm, and Tempo Off. Plug in DlyTime A & B at around 100-125 ms. Adjust that up or down if it's too slow / fast for what you want. Leave both Fdbk A & B at 0. Roll of the highs somewhat with Filter. Mess around with the Xnob for "raunchiness", and the Depth and Speed if you want to add some authentic pitch variations to the repeat.
I don't own a TimeFactor, but I use a similar approach with the PitchFactor.
