Hey, I just bought a beautiful 77 shorty 4x4 xlt with a 429 in it. It is a healthy engine, and it runs quite well. My trouble is, when I stomp on it, it pulls hard for about 5 seconds then bogs like it is running out of gas! The carb is an Edelbrock 600. Could it be too small? The fuel filter looks clean, but could the fuel pump be failing?

 

I've ran a 600 edelbrock on a 429 and 460 without problems. Even though it may be small for the cubic inches it shouldn't do what yours is doing. Check the float level, it may be to low and causing it to run out of gas or the fuel pump is weak.

 

This problem is all about volume. Either the pump is not adequate, or something is limiting the supply.
Had a vehicle in the shop not long ago with a similar problem, and it turned out to be the glass fuel filter. I see these see through filters on vehicles all of the time, and while it may look neat, the fittings are only 5/16". Usually a rubber hose is used to attach it to a carb, and the 3/8" line has to be squeezed down to the smaller size.
This smaller size is not large enough to flow enough volume. Like a resitrictor, the fuel can flow into the bowl(s) as fast as the engine consumes it. The end result is a vehicle that runs out of fuel at WOT.
Thats my guess.

 

So, in this instance, should the fuel line be 3/8 inch all the way from the tank to the carb?
I also have a 429 but with a Holley 600 and sometimes it does the same thing, but not all the time. Are yo saying 5/16 line might be too small for the volume needed?

 

What you need is an in line fuel pressure gauge hooked into the system and taped to the w/screen so you can see it when the fault occurs. what color are the plugs as that is a good indicator of lean burn/fuel starvation. If the porcelain insulator, after a good hard run with the fault happening, is white - it needs more to drink. then look at fuel delivery or supply problems.
I hope this helps
Kiwi