Originally Posted by
Dynamic
33 mm distance between each rails on the selle
35mm distance between rails on my old saddle
Standard is "nominal" 44 mm center to center with 7 mm diameter rails.
I just measured the rails on my Selle Italia SLR (conveniently parked on the trainer next to my computer). I get 36 mm between rails and 7 mm rail diameter which would be 43 mm c-c. I could readily believe a 1 mm error in my ID measurement (old calipers and older eyes) so it is probably 44 mm.
Sounds like your new saddle's rail width is off standard by about 4 mm.