ok just tried again, and it just goes to rev out of control without any throttle and then flames out and dies, every now and then the idle goes stable but it still just wont run without the ignitor on it. dont seem to have an excess of fuel any more, just the occasional flame out from the pipe. i did check the seal before i put it back in and used some high temperature silcone sealant around the carb shank so i dont think its a air leak.
thanks for the help guys i am supposed to be running on sunday its the cobra's first outing and i would like it to be at least running.

UPDATE

still no joy, gone from super rich too super lean, on the lsn and nothing seems to make a difference it starts sort of revs for about 2 to 3 seconds and the dies. once every 10 goes the idle goes stable for 5 seconds and then dies, and then it starts all over again. at a complete loss.