I have had my car in a heated shop all winter. I made some modifications and finally got it running nicely. I took it home and put it in the garage. It is about 30°-50° in the morning and really hard to start, after the initial it starts great.

What causes this and what can I do to fix it? Could my timing be too advanced?

I have a holley carb with electric choke.

What exactly does it do when you try to start it cold?
Describe the trouble a with a little more detail, and I may be able to help.
Mark

After sitting overnight. I give it a squirt or two of gas and turn it over. It turns, but just won't fire up. After a few minutes of repeated trying it will eventually sputter, then once more and it starts. If I move the distributor to advance the timing, it fires right up, no hesitation. When I set the timing back to where it should be, the next day it is hard to start.

Are you sure there is gas in the carb when you try to start it?
When it is cold, try pressing the accelerator pump arm while looking down the primaries to see if it squirts into the carb.
Also make sure the choke is closed before starting. Adjust the electric choke so that it has very little tension, just enough to hold it closed. Also check to see what your total advance is. Get a peice of timing tape from your local speed shop and put it on the damper. Run the engine at 3000 rpm and you should have between 28 and 32 degrees total advance. If it is erratic, you may have distributor problems. If this stuff does not help, then we'll try something else.

Woody, thanks for the help. I checked what you said and played with the timing. I believe I have fixed the problem. I think it was too far advanced. I also changed the configuration of the vacuum lines, so I do not have as much vacuum while starting. I have tried it a number of mornings and it has started. I have left it sit for 4 days now, so the next start will be the test.