MGB with rebuilt engine and replacment 2bl weber carb. when cold which means sitting for a day or overnight it starts well (about 3-4 seconds of cranking) after a drive it will restart well if you retry immediately but if it sets for a while it is very hard to start. many attempts at 10 second cranks. I dont think its flooding.

Two things to look at is make sure choke is working properly and fuel pressure regulator is set properly. I run my regulator at setting 2. I have found my 71 B to be very temperamental in cold weather with the Weber downdraft and its been that way since I installed the system back in 1983. Great in summertime, fussy in the winter.