Why does this happen?

72red,
My 72 suffered from similar issues. Your tank may have lots of crap in it to clog the filter. The fuel filter screws in to the carb and clogs easily. I learned the hard way to replace the filter twice a year and always travel with a spare. They are easy to get at NAPA for a modest 5 bucks. I would highly recommend draining and flushing your tank and replacing all of your fuel lines if they are the original or of undetermined age.

This is probably still not your problem. Even with these repairs my car would still be hard to start if I did not run it at least once a week. I replaced the OEM carb and manifold with a 650 BG Speed Demon and Edelbrock Performer. The car has never run better. Always fires right up and a noticeable improvement in overall performance. If you want to maintain 100% originality you will most likely need a total rebuild of the carb and replacement of the electric choke.

I've got the BG 650 Speed Demon (I got it second hand but only slightly used on Ebay for about $260.) mounted on a Blue Thunder two plane on #7102. I'm with Pantera 4134, the car starts easily and runs great, from the first try, right out of the box. One pump of the gas pedal and it starts and settles down to idle just like it was fuel injected. I'm probably running a little rich though because it doesn't seem to like any choke at all when cold, but no black smoke and the plugs look good too.

Had one little hiccup early on and kind of an exciting one too, when the secondaries stuck open. The linkage piece that limits their travel was slightly bent and then inserted in the wrong hole (by the prior owner fooling with it I guess-can't believe it came from the factory that way). The tip of link would hang up on another piece of linkage. I straightened it and stuck it in the hole it now lined up with. No other issues now in 3000+ miles.

Definitely replace your fuel filter AND your carb. At a minimum, the carb needs to be rebuilt, but for a few dollars more you can replace it with a new BG Demon or Holley (I have a 670 Avenger) which will offer superior performance and efficiency.

Want to thank you guys for the thoughts and suggestions. The car runs well but I am sure the choke is shot, I should think about a fresh carb down the line here - I think I am going to have to put up with starting woes for a bit until my bodywork is done. The inline carb fuel filter replacement should be done though. Any idea on the part number at NAPA?

This should be it. FIL3019

http://www.napaonline.com/MasterPages/NOLMaster.aspx?Pa...n=Fuel+Filter+(Gold)