400ex won't start
 

Broke a valve spring and replace it. Put everything back in place the way it goes. Adjusted the timing, and valves to spec. Once everything was put back together. it very slowly cranked for about 3 seconds then died. Sounded like it had an air leak down there too. Popped it on the charger and fired up. How ever, smoke came from the fin's on the engine and cut out when I gave it gas. Any thoughts? New to the fourms. Thanks.