The White Smoke??????

[Sreds13]

Ok so here it is my unexpected issue I just dropped an Sr redtop into my s13. Sounds great and it is but a problem has emerged. I'm at about 500 miles since I first drove the newly built car and all has worked great. The other day I started the car and took off came to a stop and when I took off a cloud of white smoke poured out of my exhaust. After that first time it never did it again for the rest of the day. Next time I took the car out I let it warm up and all was fine. Yesterday was the first time I started it up and took it out in about a week so I let her warm up ( a little bit of four play before taking her full throttle. ) I hit the road come to my first stop sign and as I'm waiting for the intersection to clear I notice the smoke again as I come off of the clutch and gas it up more smoke soon fallows by second gear it stops, next stop sign it smokes again this time I'm able to get into fourth gear and it never smoked for the rest of the day. What is this I thought head gasket but the oil is fine not milky, my water level in my rad stays as is and with it stopping after 1st gear what the fuck is causing this??? Let me hear what ideas or diagnosis you have.