Edelbrock Free Troubleshooting

How Loose Can The Throttle Shaft Be?

Probably around 1/32? of free play, but more importantly what does it do when you spray carb cleaner around the shaft. If the RPM stays steady, you don’t need to do anything about the shaft.

When you do need to bush the shaft use 22-172bushings.

Flooding

Flooding on an Edelbrock carburetor is a situation where the float bowl is getting too much fuel and it is pouring over the top.
Some of the causes, not in any order.

Fuel pump pressure – test your fuel pump. New pumps are especially suspect. Should be 4 to 5 lbs.
Bad float – heat some water and immerse your float. Bubbles would indicate a leak.
Float sticking – gently move the floats up and down to make sure they aren’t sticking somewhere.
Worn float pin
Needle – Putting any pressure on the needle when adjusting the float can damage the viton tip and then it will not seal. Test the needle & seat
The seat uses a metal washer and they don’t always seal. Unscrew the seat and screw it back in will help. Turn the top upside down with the floats resting on the needles. Blow in the inlet gently. You should not be able to blow through.
Float level – Should look level with the top upside down.
You may be getting dirt in the needle & seat – this could be caused by a dirty, or old gas tank. Ethanol is a great gas tank cleaner. Unfortunately years of built up material on the inside of the gas tank will be sent up to the carburetor.

Off road – you may need a spring loaded needle & seat.

Hard Starting

Hard starting can be from so many different things that it is hard to point to any 1 thing.

You 1st need to determine if the hard starting is from flooding, or lack of gas.

If when you do get the vehicle started and you see black smoke out of the tailpipe, then you are flooding.

If the smoke out of the tailpipe is not black, then you are probably too lean.

Too Rich (too much gas)

Check the points, plugs, wires and any other ignition component.
Look down the carburetor after turning it off. Any gas dribbling from the venturi indicates a problem with gas getting siphoned from the float bowl.
- Test the main discharge.
- Gas cap should be vented – test by driving with the gas cap loose and look for discharge problems.
- Vent line going to the gas tank might be plugged.
- Check for any carburetor vent plugging.
- Float level
- Float leaking
- Needle & seat leaking
- Fuel pump pressure too high

Too Lean

Popping through the carburetor might indicate a lean condition.
Fuel pump pressure too low.
Kinked, or collapsed fuel line. Be sure all rubber hose is injector ready. Ethanol can eat the inside of rubber. Any black particles in the float bowl would be an indicator of the Nitrophyl float getting eaten, or the rubber fuel line collapsing inside.
Float level
Float drop not enough to allow the needle to pull out of the seat.
Fuel filter plugged. Look for in-line as well as filter screens in the fuel inlet and possibly connected to the needle & seat.

Make sure the choke valve can open & close. If the valve is stuck closed, then the engine won’t get enough air to start.

Dies or hesitates when stomping on the gas.

Fixing an Edelbrock Carburetor Hesitation / Stumble

A hesitation, bog, or flat spot when you step on the gas with an Edelbrock carburetor (typically an AFB-style design like the 1406 or 1405) almost always points to an issue with the accelerator pump circuit or transition circuit.

When you snap the throttle open, air rushes in instantly. If the fuel doesn't hit the cylinders at the exact same fraction of a second, the engine leans out and stumbles.

1. Check the Accelerator Pump Arm Linkage (The Quickest Fix)

Edelbrock carburetors have a linkage arm on the driver's side that connects the throttle to the accelerator pump plunger. This arm has three different hole positions (labeled 1, 2, and 3 or inner, middle, outer) to adjust the pump stroke.

The Problem: If the pin is set to the inner hole (shortest stroke), it might not inject enough fuel volume when you step on the gas, especially with heavier vehicles or larger engines.
The Fix: Move the linkage pin to the outer hole (or the hole closest to the tip of the arm). This increases the pump stroke depth, delivering a larger, more aggressive squirt of fuel immediately when the throttle moves.

2. Inspect the Pump Nozzles (Squirters)

Look down into the primary venturis with the engine off and air cleaner removed. Snap the throttle linkage by hand. You should see two crisp, instant streams of fuel shooting straight down into the boosters.
If there's a delay or weak dribble: Your accelerator pump leather/rubber plunger inside the pump well may be worn out, or the tiny discharge check needle/ball beneath the nozzle screw is stuck or gummed up.
If it still hesitates after moving the linkage arm: You may need to step up to a slightly larger nozzle size if your engine has a high-performance intake or low-vacuum setup.

3. Check Transition / Idle Mixture Settings

If the hesitation happens right as you transition from idle to part-throttle (often called an off-idle stumble):

Idle Mixture Screws: Your idle mixture might be too lean. Try backing out both idle mixture screws (counter-clockwise) 1/4 to 1/2 turn to enrich the idle/transition circuit.
Curb Idle Speed: If your curb idle speed is set too high, the throttle plates expose the transition slots too early, throwing off the progression. Ensure your hot idle is set correctly (usually around 600–700 RPM in neutral/park).

4. Check Ignition Timing (Often Blamed on the Carb)

A weak initial timing advance will mimic a carburetor hesitation every single time.

Check your base timing and ensure your vacuum advance canister is hooked up to a ported vacuum source (not manifold vacuum, depending on your distributor setup) so that timing advances cleanly when the throttle opens.