Hi everyone - I have been experiencing something very strange and want to see if anyone else has experienced this.

’79 L42 matching number car

When I am parked with a slight forward incline and gas is at a quarter tank level, the car will not start.  
if I level it out, put gas directly in the carb, it starts up and pulls fuel from the tank as it should.  

Strange to me! 

Thanks for your comments

EDIT: The car does initially start and I go maybe 50 feet until it stops.  Gas does not flow to the carb (The gas filter is empty)

Does it have to sit parked at that incline overnight for this to happen, or it is more immediate? Either way, if you have to add fuel to the carb for it to start, then my opinion would be that you have an internal fuel leak from the carb bowl. That is the only way for fuel to leave the carb while parked....except for extended periods of time, when the fuel will evaporate. Assuming you still have the OE Quadrajet carb, another idea is that perhaps the fuel filter check-valve is missing, and the fuel is draining back to the fuel tank when parked uphill. I know, it's a stretch, but it can, and has happened. 

Thanks Adams Apple

It can be as short as me having dinner to have this issue.  
I need to check the fuel pressure (I need to purchase a gauge)  

The carb is an Edelbrock 9605S 

Missing check valve excellent suggestion Adams Apple!  I do not know if that has one inline   Where exactly would I see that?

I appreciate the assist

Is the check valve typically where the gas line goes into the carb?  

EDIT: The car does initially start and I go maybe 50 feet until it stops.  Gas does not flow to the carb (The gas filter is empty)

Otay! So the car will start and run for a minute or so...that's better. Since you do NOT have the Quadrajet carb, the check-valve is moot. The Quad filter has the valve...it is right in the carb where the fuel line connects to the carb. Now then...my thought now goes to the possibility of the fuel tank bladder being deformed, and either giving you an incorrect fuel level reading, or it could be moving the fuel away from the pickup/filter when parked on an incline.

Another "stretch" is that you might possibly be dealing with a vapor lock situation, where the fuel is hot after parking, and it creates a vapor lock between the fuel pump and the carb inlet, preventing fuel from getting into the bowl. This would ONLY happen after driving...it would NOT happen after an overnight, or even an hour or so cooldown. Could also be a fuel pump problem....might need to do a pressure check WHILE the problem is taking place.

Thanks Adams Apple!  I will start checking things - and order a pressure gauge as well.