LT1-LT4 Modifications - car wont start after motor swap

i put a new motor in my car and cant get it to fire over... i put a spark tester on it and i have an weird spark kinda like it sparks when it wants to... any ideas

Does the starter engage when you turn the key?

yeah it turns over and everything... just something is wrong with the spark it doesnt arch off as many times as it should.