Quadrajet - Bogging out

[swissarmychainsaw]

So this just started happening. Under load (like making a dump run) my 1975 GMC 350/350 Quadrajet would bog out. As in you give it some gas and it sounds like its drowning. (this truck is new to me and I'm slowly working through a bunch of issues on it)

So it will work OK with LESS throttle or even with MORE but there is a zone it does not like.

It's a bit weird, because (now unloaded) it does not bog out all the time.

I believe the carb is original and likely could use a rebuild, but I would kind of like to know "what specifically" is going on before I just buy Cliff's book and rebuild kit and go at it.

I have NOT done a real tune up on this thing, and I will as a first step.

I am kind of wondering if it is getting too much fuel or not enough.

Cliff's book comes tomorrow. I'll start posting some pics as I go.

One thing: The PO put he air cleaner lid on upside down (so you can see the air cleaning with the lid on). When I put this on correctly, the truck would bog out when you gave it gas (like, engaged the secondaries). I was not sure what to make of that, but returned the air cleaner lid to the upside-down position and things were back to "fine" for a while...

Nick