First of all, it'd make more sense for this to be in either "Other", "General Questions", or an "Engine" section, since carbs aren't block-size-specific. Anyway.

I have a newish carb on my car, a 4 barrel Quadrajet, and two older, disfuct Quadrajets from my first car. They're different from the newer one, though, and I wondered what this difference meant. The first picture is of the newer one.

EDIT: See third post for updated situation.

 

The first one is an older casting.
The second one is a newer casting with an adjustable power valve (well, I think it's not called a power valve in that series, but it's the same thing).
Both should work fine, if set up correctly, and if the throttle shaft bushings aren't worn out.

- Eric

 

Will either of them deliver more mileage and/or less foul emissions?

The reason I took my otherwise working carb apart was because I have yet to clean it, and the fuel filter in the fuel line was gunky, so I decided to get a new fuel filter and clean the carb. The older carb was taken apart for reference.

Might as well use the thread for something useful;
The problem I'm having is that the car cranks, but won't start. I got no streams of fuel in the primary part of the carb, so I changed the fuel pump and filter. I made sure there was a clear line down to the tank by blowing air into the main fuel line, which blew back a neat stream of fuel. When I still wasn't getting streams of fuel in the carb, I wondered if it was plugged or otherwise gunked up. Guess not.