Hi , saturday was my first night of racing . I have a oem cutlass ,here is my wheel weights  LF=985lbs  RF=960lbs  LR=485   RR=505  , left side 50.1% and cross 49.3%  .  I changed my sway bar on front to a heavier one and installed one on the rear as the car came with none ( light ). The car came with a small V8 so i changed to a 305 with a 3 speed  , my rears are 240 something , i was told to change to 256,s as my car only revs 4000 on the straight away  then i have the turn and back out of the throttle , they tell me it just starting to pull when i have to back off , they tell me 4000 to 5000rpm is when my motor should be working the best ? The rear of my car begins to slide when exiting under throttle . Any help would be greatly appreciated .  

Well, start by getting rid of the rear sway bar, those will make you loose.  
-Do everything you can within your rules to move wieght back in the car. relcate the battery, etc.
-Get your spring pockets setup so that you can shim them to change the crosswieght (if rules allow).  -Definitly change the rear gears so you can get to at least 5000-5500 rpms
-if rules allow, get some springs, and try a lighter one in the right side if you're still loose after ditching the rear bar.  

Hi , thanks for the info . The next race is in 2 weeks i will let you know how i made it !  

I would say that you need a 2.73 rear gear to achieve the RPMs that your motor wants.  You should hit about 5200 at the point of letting off with those gears.  What type of track are you running, (size, banking, dirt?) Any more info will help us to better help you.