still not starting well

I'm about ready to give up on this damn thing.
I've replaced just about everything I can and my engine still doesn't start well.
Sometimes it fires up with a flick of the ignition. Other times (like yesterday) I crank on it for a half hour and have to give up.

Once it is running it idles perfectly, it has NEVER stalled off idle for any reason other than me making an error with the clutch.

When I installed the cam I didn't degree it in, I just used the two timing dots. It idles fine though (226 .050 hyd) so I wouldn't think the start up issues have anything to do with that.

I'm ready to take a sledge hammer to this thing so anyone with ANY ideas at all please let me know.
thanks

for the record:
edelbrock 650 thunder, man. choke
iron heads
tried many ign timing variations

There are a lot of things that could cause this. You didn't mention what engine your working on???? Maybe your fuel pump is going. Coil breaking down. Do you have spark when it won't start?? I can't beleave changing the cam would give you an intermitant problem.

I tested the resistance in the coil and it is still what it should be.
I have an msd box too. It's a bb chevy 402.
I replaced the cap and rotor and all plug wires.
nothing makes this thing reliable.

the fuel pump seems fine, I always manually prime the fuel system with a bulb anyhow. it's just start ups.