anilnandyala,
You should be able to do SC problems in between 60 and 90 seconds. You can take a bit longer if you're pretty strong in CR and RC, and you might need to shoot for even shorter times if you aren't. Completing a SC question in 3 or 4 minutes is as good as missing it altogether; timing is critical on this test.
I think whiplash2411's suggestion is a good one, and I'd also do the following:
1. Start the timer and do a single SC problem. If at the end of the problem you look at the timer and see that it has been longer than 90 seconds, that's something you need to work on. Start the timer over and do another problem. Check the time. Repeat this drill until you develop a mental timer that goes off after every 90 seconds or so (nobody is perfect, but you should be able to get to the point where you have a sense of when approximately 90 seconds has passed even though you are intensely focused on the question at hand.)
2. Once you can pretty reliably know when 90 seconds has passed, start the timer again and do two questions. You should be able to finish these two questions in 3 minutes. If you can't, repeat this drill.
3. Repeat this cycle of adding another question and 90 more seconds until you can reliably do 7 SC questions in about 10 minutes.
The point of this drill is to develop an internal sense of how long you have on SC questions so that you can keep yourself on track during the test without looking at the clock so regularly. This means that you'll also have to learn to move through the stages of a SC question more quickly and you'll have to get comfortable guessing. Again: Getting an SC question right in more than 2 minutes is arguably no better than guessing after 1 minute.
Good luck!
Brett