During abhijit muhurhta , Lord Vishnu himself with his Sudarsanachakra dispels all the evils.
To arrive at abhijith muhurtha, find out the actual duration of the day from sunrise to sunset and divide this into 15 equal divisions. The eighth division from sunrise is called the abhijith muhurtha. This will be on both sides of the midnoon. Two minutes on each side of mid noon should be left as it is varjya.
Example - Sunrise 7:00 am, Sunset 5:15 pm
Day duration = 615 minutes
600 minutes / 15 = 41 minutes
Eighth division starts at 7:00 am +287 minutes = 11:47 am and continues for 41 minutes till 12:28 pm.
The mid noon is at 12:07:30
Two minutes on both sides of this ie:- 12:05:30 to 12:09:30 is varjya.
Leaving aside these four minutes the rest of the 37 minutes of abhijith muhurtha is acceptable.