Help understanding carburetors - metering rods and jets

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cudajames

cudajames

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I am in the market for a new carburetor; looking at the edelbrock 600 CFM performer series. There are 3 models to choose from that all have differences; with one marked for fuel economy and another performance
The 1406 (fuel economy) seems to be the most popular (cheapest), has .098 primary with .095 secondary, 4” spring and .075x.047 metering rods
The 1400 has .098 primary with .095 secondary, 5” spring and .073x.047 metering rods
The performance model is the 1405 which has .1 primary with .095 secondary, 5” spring and .070x.047 metering rods

What performance differences does the larger step-up spring make?
And what difference does the smaller metering rods make? Does this limit the amount of fuel that moves through the jets? Or the rate of fuel delivery to the jets?

The 1400 and the 1405 with the electric choke kit are about the same price. And the thunder 1806 650CFM has .095 primary with .098 secondary, 5” spring and .068x.047 metering rods is just a little more expensive
Thanks for the education
 
Try reading this:

[ame]http://www.edelbrock.com/automotive/misc/tech-center/dl/carb-owners-manual.pdf[/ame]
 
The 1406 is an electric choke model
1405 is the manual choke model
They are the same carb otherwise.

Step up springs are what determines how much fuel is allowed through the jets at any given throttle and have no specific bearing on performance or non performance, as they come in different strengths (poundages) that determine how much the needle rises out of the jet under different vacuum levels. (caused by throttle position)

I would call the 1405 and 6 as nice reliable daily driver carbs and the Thunder series as a more performance oriented carb.
The electric chokes on the 1406 series work perfectly, and are nice for a daily driver.
If you want more control over the choke amount, duration and warmup RPM's go with the 1405 for the manual choke.
 
The 1400 is the "emissions" carburetor and it has a ported and EGR vacuum port on the front (no manifold), though I'm thinking the power brake port on the back could be used for manifold vacuum. It also has a specific fuel vapor connection for the charcoal canister (if you have one). The manuals don't have any tuning changes for the 1400 since Edelbrock looks at it as a carb that shouldn't be altered. I'm not sure if anything else internal is different between the 1400, 1405 and 1406.
 
TrailBeast said:
The 1406 is an electric choke model
1405 is the manual choke model
They are the same carb otherwise. I would call the 1405 and 6 as nice reliable daily driver carbs and the Thunder series as a more performance oriented carb.
The electric chokes on the 1406 series work perfectly, and are nice for a daily driver.
If you want more control over the choke amount, duration and warmup RPM's go with the 1405 for the manual choke.
Click to expand...

this ^^^^ exactly. you can buy a calibration kit that has a variety of jets/springs/rods and instructions.


http://www.ebay.com/itm/edelbrock-c...Parts_Accessories&hash=item2a48cb6a0c&vxp=mtr
 

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NukeBass said:
The 1400 is the "emissions" carburetor and it has a ported and EGR vacuum port on the front (no manifold), though I'm thinking the power brake port on the back could be used for manifold vacuum. It also has a specific fuel vapor connection for the charcoal canister (if you have one). The manuals don't have any tuning changes for the 1400 since Edelbrock looks at it as a carb that shouldn't be altered. I'm not sure if anything else internal is different between the 1400, 1405 and 1406.
Click to expand...

The large port on the rear of the carb is not really for power brake connection, but can be used as such. It is really for PCV hookup. Power brake vacuum should be hooked to the large port in the manifold runner(s).
 
This is simply my opinion base on my experience. Take it as you will. You have been given excellent advice as far as the reading material above.

I disagree however, with the 1400 series consensus. If you want a really great performing carburetor, choose the 1800 series over the 1400 series.

The 1400 series is bases on the Carter AFB. They were decent carburetors. But the Carter AVS was a big step up in improvement over the AFB.

The 1800 series is based on the Carter AVS. They are considered superior to the AFB for several reasons but the number one reason is the smoothness of the transition into the secondary side of the carburetor.

The reason for this is unlike the AFB style carburetor, the secondary boosters are located under the secondary air door instead of on top of it. This allows for a much more accurate air signal to the boosters and results in a much more smooth operation of the secondary side.

Also another great benefit is the AVS style carburetors, much like the Thermoquad, are a vacuum secondary design. This means that they are much more forgiving in an over carbureted situation and that one size carburetor will work on a variety of engine sizes.

Since the AVS style carburetors will only flow what the engine demands, that means they will never "over carburete" the engine. Rich primary conditions can easily be adjusted out, since they have an almost infinite adjustability with springs, metering rods and jets.

IMO they are probably the dead best carburetors out there for a street or street/strip car. Repair parts are cheap and plentiful. It's not like trying to find a needle in a haystack tuning kit for a Thermoquad, because all kind of tuning kits are available.

IMO, the 1800 AVS Thunder carburetors leave the 1400 series in the dust. That's my story and I'm stickin to it.
 
Two7T3Dart said:
The large port on the rear of the carb is not really for power brake connection, but can be used as such. It is really for PCV hookup. Power brake vacuum should be hooked to the large port in the manifold runner(s).
Click to expand...

The PCV port is on the front. The back one is a threaded connection that you can either plug or put in a hose connection. The manuals say it is for power brakes.
 
Triple R thank you for the great write up.

Also further research on the 1405 and 1406 has found they are different carburetors beyond metering jets and rods.

http://www.forabodiesonly.com/mopar/showthread.php?t=146279

Billbo does a great write up

At this stage it is between the 1405 and 1806. Especially since they are all real close in price that will not be a variable. And I don’t think 50 CFMs will be much of a difference
 
NukeBass said:
The PCV port is on the front. The back one is a threaded connection that you can either plug or put in a hose connection. The manuals say it is for power brakes.
Click to expand...

Since they are both manifold vacuum sources, it does not make a hill of beans difference other than perhaps location which port is used on what.
 
cudajames said:
Triple R thank you for the great write up.

Also further research on the 1405 and 1406 has found they are different carburetors beyond metering jets and rods.

http://www.forabodiesonly.com/mopar/showthread.php?t=146279

Billbo does a great write up

At this stage it is between the 1405 and 1806. Especially since they are all real close in price that will not be a variable. And I don’t think 50 CFMs will be much of a difference
Click to expand...

I had wondered about this, too. Thanks for the link.
 
73AbodEE said:
Interesting although I will be using 2 1406's lol
Click to expand...

The AFB style carburetors are better for dual quad applications. But for single four, they are not even close to the AVS, IMO.
 
cudajames said:
Triple R thank you for the great write up.

Also further research on the 1405 and 1406 has found they are different carburetors beyond metering jets and rods.

http://www.forabodiesonly.com/mopar/showthread.php?t=146279

Billbo does a great write up

At this stage it is between the 1405 and 1806. Especially since they are all real close in price that will not be a variable. And I don’t think 50 CFMs will be much of a difference
Click to expand...


Huh, thats interesting isn't it?
Everything I have seen or read from Edelbrock says they are the same carb.

Thanks for the info.
 
RustyRatRod said:
The AFB style carburetors are better for dual quad applications. But for single four, they are not even close to the AVS, IMO.
Click to expand...

Don't get me wrong, l love the AVS , in fact I have 2 of them sitting right here waiting their turn to be ran and tuned. I have always preferred them since the good ole days. It has only been in recent years that i started messing with the AFB performer series and I am really liking them for every day use as well
 
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