For starters go out and do an event run of 350m and run it as fast as you can.
The whole practice should go like this.
200m at 4 secs of your race pace.
5 minutes rest
300m accelleration run. 100 easy- 100 float- 100 sprint. This time should be close to your goal time for the 350m.
10 minutes rest
350m event run, a controlled acceleration to start reaching your peak speed in the first 80m relax coming out of turn, stay relaxed down the straight, and in middle of last turn try starting to drive again thru the numbers. Then finish running past the 350m mark.