OK...some history first. I have been fighting this truck tooth and nail getting it to run right (or at all). I thought I had it fixed, only to have it not run at all the next day. The problems seemed to arise soon after I put in a new sending unit in the rear tank. The carb is an edelbrock 1406 (freshly re-built). Anyway, it wouldnt start and I suspected the carb got gunked up due to dirt getting into the tank while replacing the sending unit. I pulled the top of the carb off and cleaned it out the best I could without tearing it completely apart and soaking it. Put it all back together and went to start it. The only way it would start is if you crank the hell out of it with the throttle wide open. After it warms up a bit, it runs beautiful, even starts right back up. This morning it started the same way, crank the hell out of it with the throttle wide open. What I was considering is pull the carb completely apart (again) and soaking everything in chem-dip for 5-6 hours or so. While the carb is soaking, disconnect the fuel line at the sending unit and at the fuel pump and hook up an air compressor to it and try to blast the lines clear in case there is gunk in the lines. Any thing else I should do? Or could this be a different problem altogether? Suggestions would be greatly appreciated, thanks. The reason that I hesitate on re-soaking the carb and all that jazz is that after this thing runs for a bit it runs perfect. It seems to me if things were very clogged it wouldnt run so good after warmed up. Maybe it is just a simple choke adjustment. I know the timing is off because I was playing with that as well (without the light). But I dont think the timing is off much.

 

The first thing I would do is to install a see-through filter in the rubber fuel line coming out of the tank. That way you can get an idea of how much trash is coming out of the tank. I run three filters. One at the tank, one between the fuel pump and carb, then the carb has one that screws into the bowl. This is what is needed to keep the carb clean.
It only takes one speck of dirt in the wrong place to cause your carb to act up.
I would retrace your steps to find your start problem. Check the choke first.

 

Two "good practice" tips:

1) It's never a good idea to halfway rebuild the carburetor, or clean out parts of it. If you're going to open it up and clean anything, it needs to be rebuilt completely. Often times, opening it up and cleaning out what you can see causes more harm than good.

2) Adjusting the timing without a light is shooting in the dark; there's no way to verify how far it is or is not off time if you're not using a timing light.

Since both of those apply to your situation, you might be chasing your tail in diagnosing these issues. But since it does run once it's warmed up, it sounds like a choke issue. When you start a carbureted engine, you must press the pedal once to close the choke. This releases the fast idle linkage so that the choke can close. Pressing the pedal much more than that can easily flood the engine.

 

I think I usually press the pedal twice at first. I will try just once this morning and see what it does. I will get my timing light and get the timing set back to where I had it initially. I know it is off.

 

I would look down on the carb and work the throttle linkage and see if gas is making its way through the carb. It takes less gas then you'd think to let the motor run. If gas is coming through, you know its timing. I still have points and it loosens up and gets out of tolerance, which is usually the culprit for my truck. I still always check to make sure its getting gas, because that cuts out 1/2 the troobleshooting.
Hope my rambling helps.

 

Usually the very first thing that I do when it wont start at all is operate the throttle linkage while looking down the carb to ensure it is getting fuel. My only problem is when it is stone cold. I find if I hold about 1/2 throttle and keep cranking it will start. Once that happens, it runs awesome. I am going to tinker with it today since the weather cleared. I think the choke got out of whack somehow.

 

If its nice out, wire the choke open and see what happens. I had a 302 a few years ago that started when it was 17 degrees with the choke wired open.