Need help with edelbrock 1406 carb

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RLF Cuda said:
Lean or rich are tuning issues that essentially all carbs need to be correct for a given application. The original jetting may be lean for Carter/Edelbrock carbs, but that is just a metering rod or jet away. My experience with Carters is great. My 340 FB FS was no faster with a 750 Holley than the original AVS, but the AVS got far better fuel economy than the Holley.
What is more of an issue today is the quality of fuel. Ethanol eats the inside of carbs if let to sit for any length of time, and ethanol destroys Viton seals causing flooding. This can happen to any carb. Ethanol also eats the plating on steel gas tanks putting rust and oxides into the fuel system, also leading to leaks.
For us, the sad thing is, ethanol does nothing for emissions or performance unless you design the whole system to be compatible with it.
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It's not just the jetting and rods with those. It's everything. It's the boosters as well. There's a thread around here somewhere showing just how many differences there between the 1405 and 1406. People can flip and flop it and argue it however they want, but the two carburetors are vastly different. It's been well documented.
 
RustyRatRod said:
It's not just the jetting and rods with those. It's everything. It's the boosters as well. There's a thread around here somewhere showing just how many differences there between the 1405 and 1406. People can flip and flop it and argue it however they want, but the two carburetors are vastly different. It's been well documented.
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That is correct, but my point is that tuning is required no matter which car brand or type used to get optimum performance. During the '76-'77 gas crisis, i changed the cam in my 340 to a 318 cam, tuned the AVS to perfection (leanest AFR for power) and used 2.94 gears and 28" tall tires. I got 24-25 MPG on drives from LA to SF or the like and actually went from South SF to Irvine, CA on one tank of gas. ~400 miles. The car still turned 14.50's at OCIR with this setup, so it was no slouch, but down from 13.50's stock.
 
RLF Cuda said:
That is correct, but my point is that tuning is required no matter which car brand or type used to get optimum performance. During the '76-'77 gas crisis, i changed the cam in my 340 to a 318 cam, tuned the AVS to perfection (leanest AFR for power) and used 2.94 gears and 28" tall tires. I got 24-25 MPG on drives from LA to SF or the like and actually went from South SF to Irvine, CA on one tank of gas. ~400 miles. The car still turned 14.50's at OCIR with this setup, so it was no slouch, but down from 13.50's stock.
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I believe we all get that. I don't think anyone disagrees.
 
Ok. Took off the top, remeasured the floats, made sure they didn’t have any holes. The mechanical pump is supposed to be 6psi. Fuel pressure measurement is 7-8 psi. Fuel dripping from the venturis during idle. Sure looks like lots of fuel to me.
 
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No fuel should be dripping from the venturis at idle. Only fuel to the engine comes from the idle mixture screws. I would try replacing the needle/seat and set the float slightly lower than specifications. If this solves the issue, consider resetting the floats to specs. 1/16th to 2/16ths lower than stock should work but may lean out the mixture under power. But this will put slightly more pressure on the seats.
 
RLF Cuda said:
No fuel should be dripping from the venturis at idle. Only fuel to the engine comes from the idle mixture screws. I would try replacing the needle/seat and set the float slightly lower than specifications. If this solves the issue, consider resetting the floats to specs. 1/16th to 2/16ths lower than stock should work but may lean out the mixture under power. But this will put slightly more pressure on the seats.
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Thank you. The needle seats and needles are brand new, floats are set at 7/16”. I got a pressure tester on it and it’s at 7-8 psi. The floats would need to be set higher not lower, correct? Greater than 7/16” to put more force on the needle? I think I’m at the point where I’m either going to throw a regulator on it or go buy a street demon….
 
Sorry, float settings are from different perspectives. Larger number means lower fuel level. As they are upside down when you measure them, it all depends on how you look at them. 8/16ths or 9/16ths may help, but lower fuel pressure may actually be the better solution.
 
Weird stuff. I put a regulator on it, still dripping from the venturis. Took it all apart again and found one of the venturis clogged. Cleaned it, and still dripping…. I don’t mind just buying another carburetor but man this just seems like it shouldn’t be this hard.
 
With your higher 7-8 psi of fuel pressure, set the floats to 1/2" [ not 7/16" ].

You have a flooding issue & it is not due to the 7-8 psi. The needle seats should have a washer under them. Flooding will happen without them. The fuel inlet system on these carbs is very simple....& robust. Binding, leaking floats etc cause flooding. Make sure the floats move freely. Make sure the baffles [ one in the air horn, one in the body ] are not interfering with float movement. Before refitting the air horn & suck on the fuel inlet. If you can suck air, it will flood....
 
RLF Cuda said:
What is more of an issue today is the quality of fuel. Ethanol eats the inside of carbs if let to sit for any length of time, and ethanol destroys Viton seals causing flooding. This can happen to any carb. Ethanol also eats the plating on steel gas tanks putting rust and oxides into the fuel system, also leading to leaks.
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I had this issues several years ago and was at Carlisle where Herb McCandless recommended a product called Carb Defender from a company called Driven. I have used it religiously ever since on 3 carbed LA motors and the Weber on my Rampage with no further issues with internal corrosion.
 
Very helpful this is. It looks like I have a lot of orifices to check. Different symptoms though. Starts right up, idles good although smells like it's on the fat side, in gear and part throttle not so good, give it a little pump on the pedal, smooths right out briefly. The hot rod does not have the stock fuel tank in it. It appears to be well constructed, but no idea if it's plated inside, a magnet won't make it down the fill spout to check for rust particles in the tank. Clear fuel filter is installed now, will see if any junk is visible in the fuel.
 
Bewy said:
Let's cut through the bullch*t.

- 7miles out:
Do not use an elec pump with a mech pump to stop vapour lock. It won't work...... Neither pump is designed to work with another pump. If you want to avoid vapour lock, use the elec pump by itself.........or else I have been incredibly lucky over the last 50 yrs.
- When Edel started making Carter AFBs, they changed very little. One thing NOT changed was the fuel inlet/delivery system. The parts are interchangeable. The robust design can be used up to 10 psi fuel pressure [ yes, 10 ]. Float level needs to be adjusted for [a] n/s size fuel pressure. The 5.5 psi figure bandied about for Edel carbs is the datum pressure. more pressure will raise fuel level & vice versa. Adjust jetting accordingly.
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Bewy - Sorry I'm late noticing your reply. I'd be interested in removing the mechanical fuel pump and following your advice. Is there some kind of fuel pump block off plate or something? I'm going to have to search it out now.
 
7milesout said:
Bewy - Sorry I'm late noticing your reply. I'd be interested in removing the mechanical fuel pump and following your advice. Is there some kind of fuel pump block off plate or something? I'm going to have to search it out now.
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Small block chevy bolts right up, even uses the same gasket.
 
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