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Edelbrock carb problem! 1406

46K views 28 replies 11 participants last post by  bigsky 
#1 ·
Just had my motor rebuilt to a 383 stroker, new m22w muncie 4spd tranny. New ignition, heads, cam, etc..... It starts great, idles great, drives great, slight acceleration is great, BUT, when I'm in gear cruising and I slam it WFO it falls on its face than takes off, no matter what gear or anything else. I printed the manual for the carb, it has the plain color step-up springs and the metering rods say 6552 on them, which I dont know what that means. I set my pump rod to the lower hole like the manual suggested and It changes nothing, any suggestions? Also I had it dynoed and the A/F numbers on the left ranged from 13.7 to 14.3 and the right side ranged from 11.9 to 13, according to the manual this is the optimal range, so I gathered that the A/F is not the problem.
Thanks for the help, Jeff

:beers:
 
#2 ·
I would look at the squirters that the pump sends the 'shot' to. If it is an economy carb, then it might not be letting enough fuel for the sudden surge that you are asking for. More af a little weak stream. (When you turn 65 or so, you will know exactly what this means.)
Anyway, (I'm only 57 so I have no idea what I'm talking about.) I would look to increasing the orifice size with a different 'squirter'.

Others will have different opinions I'm sure, but it should not hesitate when you punch it.

Mike
 
#3 ·
I believe I just found my problem, I wrote an email to edelbrock and they said you cannot use a 1406 carb (600cfm) with a RPM or Air Gap intake. I have an RPM intake, so they suggested the 1407 which is a 750, so my question is, would you advise this carb or something different? Also if this carb, it comes without a electric choke and it is 55.00 to buy one for it, but, will my choke off of my 1406 swap over to the 1407? Thank you, Jeff
 
#4 ·
I'm using a Carter AFB Competition Series on an Edelbrock Air Gap - it works fine. I personally cannot see any difference in the 1406 or the Carter... besides, I have numerous AFB style carbs and it seems much in the carbs is interchangeable. Yes, you can install the choke from the 1406.
Why did they say it would not work on the Air Gap?

Mike
 
#5 ·
I'm using a Carter AFB Competition Series on an Edelbrock Air Gap - it works fine. I personally cannot see any difference in the 1406 or the Carter... besides, I have numerous AFB style carbs and it seems much in the carbs is interchangeable. Yes, you can install the choke from the 1406.
Why did they say it would not work on the Air Gap?

Mike
Go to edelbrock.com select automotive, select carbs, look down the selections tell you get to 1406 and read what it says, it says that testing info that a 1406 will not perform well with a RPM and a air gap or tork, not sure on the last part.
 
#8 ·
I'm running the 1406 carb on my 350 with the Edelbrock 2101 non-RPM intake, with no issues. It's funny to hear Edelbrock support stating the 1406 should not be used on an RPM intake. The first page of their 2006 edition carburetor manual states otherwise:
Your Edelbrock Performer Series carburetor was calibrated using Edelbrock Performer, Performer RPM, and Torker II Power Packages.
Are you referring to the "Calibrating the Pump" section on page 14? You moved the pump rod down a hole as the manual suggested, which should provide more fuel but did not help the stumble. Have you also tried moving the rod to the top hole (leaner) to see if that helps?

The 1406 is intended as an economy carburetor and is originally jetted lean, but it can be tuned a good amount.
 
#10 ·
I also had the performer intake before my motor work with the 1406 and I had no issues, with the stroker and higher compression, my motor guy said I need a performer RPM, tahts when it all began.




I'm running the 1406 carb on my 350 with the Edelbrock 2101 non-RPM intake, with no issues. It's funny to hear Edelbrock support stating the 1406 should not be used on an RPM intake. The first page of their 2006 edition carburetor manual states otherwise:


Are you referring to the "Calibrating the Pump" section on page 14? You moved the pump rod down a hole as the manual suggested, which should provide more fuel but did not help the stumble. Have you also tried moving the rod to the top hole (leaner) to see if that helps?

The 1406 is intended as an economy carburetor and is originally jetted lean, but it can be tuned a good amount.
 
#9 ·
I tried every change it suggests, and tried the biggest of everything you can buy for the carb. From the performance shop I had my motor done, he says that edelbrock carbs are basically stock replacements that look cool. The biggest edelbrock carb, compares to the smallest Holley or other brands...etc. The carb was disigned to be easy to work on, and look like high performance, I dont know, just what I was told. So I orderd the 770 holley, it will be here next week, I will put it on and let you know the results, I dont know what will happen, I am experimenting. All I know is that after the work done on my engine, and the look of the car, it is quit embarrassing to have a stutter in every gear, and I want it gone!
 
#11 · (Edited)
Bigsky, Carter style carbs have been around forever and have work well in high performance setups. The problem you are having is with CFM, the carb you have will work great on a mild small block With a volumetric efficiency of 85% or less. It sound like your 383 is just asking you to feed it a little more. If my calculation are close your setup needs about a little less than 700 CFM carb. You can jet up the 1406 to get close to your 383 needs but above 5000 rpm it will lay down on you. The good news is below 4500 RPM the throttle response will be excellent :D. Go get yourself the strip kit for the 1405 and start out with the silver step up springs, the #10 setting for the primaries and a 8% richer setting for the secondaries (all on the 1405 chart). This should get you started with the edelbrock. The Holley that you ordered will be a far better strip carb for your setup.

Greg


PS 6552 on a edelbrock rod stands for .065 X .052
 
#13 ·
I would agree that the 1406 is too small, first thing I thought of before reading all the threads. Look a the 1406 base calibration vs. the 1407 and you can see how different the calibration is. The 1406 is a 600 CFM, the 1407 is a 750. So buying the 770 Holley, if that works won't "prove" the Holley is better, it will simply show you didn't have the right CFM.

BTW, the furthest hole on the squirter arm is fuel delivered more slowly, the opposite what you need if it falls on it's face. I can't explain what's on your metering rod, the 1406 base calibration is fatter than that. The first two numbers are are the cruise circuit diameter and the second two are the power circuit diameter.

Unlike a Holley, the Performer / Cater carbs allow you to adjust "when" separately from "how much" fuel on the power circuit -- the step up springs determine when and the rods/jets determine how much. You need to set idle first, then secondaries, then primary cruise, then power circuit, then squirter last.

I would start by putting the 1407 calibration in your 1406 -- this will require a secondary jet change, a primary jet change, a spring change, change in the squirter arm hole and a squirter change. Everything but the last one is available if you buy the right tuning kit, but the squirter is a separate part number. So if it's falling down, you need to do more than just a squirter change.

If everything else on the 1406 is truly in tune (with no stumbles, jerking when you slightly accelerate) try this -- jet up the secondaries, richen the primary metering 4-8% on the power circuit (book will show you the right rods) and go to the closest hole on the squirter arm.

The electric carb should swap over, I can't remember what it takes to uncover the internal vacuum passage for the choke though.
 
#14 ·
I would agree that the 1406 is too small, first thing I thought of before reading all the threads. Look a the 1406 base calibration vs. the 1407 and you can see how different the calibration is. The 1406 is a 600 CFM, the 1407 is a 750. So buying the 770 Holley, if that works won't "prove" the Holley is better, it will simply show you didn't have the right CFM.
Too little CFM does NOT cause hesitation.

Too little CFM may cause a reduction in higher-rpm power--but NOT stumbles, misfires, etc.

The problem is very likely in the calibration of the carb--amount of accelerator pump shot, squirter size, or the secondary air valve opening too abruptly.

Come to think of it--didn't Edelbrock introduce the "Thunder" series carbs which have a more-tuneable air valve?
 
#15 ·
Shurckey is on the money. I can't believe he is the only guy who mentioned the air valve when it is the first thing to check with this symptom. If it opens to soon the vacuum in the secondary is to low to signal the secondary fuel circuit. This is the classic behavior that led to the phrase Quadrabog. Adjust the spring tighter until the bog goes way. Yes, the Thunder makes this very easy, but it can be done on all carbs with secondary air doors. As for the Edelbrock being a small Holly, what a load of nonsense. Look, a 600cfm carb flows 600cfm no matter who made it. And the fuel flow is set to mix with the air flow to have a correct A/F ratio, so if Holly's 600 CFM carb can make the right A/F ratio, then so can Edelbrock's 600 CFM. I have been working on my 650 Speed Demon for the last year and it finally works pretty good, but the types of things I have had to do to get there are rediculous. The throttle plates stuck when the throttle closed due to sloppy assembly at the factory, so it would never return to the same idle twice. I had some porous castings. I had metal chips in the fuel air passages. I finally took it to a local Demon guru and he set it up for me and yes, it now works pretty good, but it should have worked pretty good right out of the box. I swapped it for an Edelbrock 650 Thunder carb and wow. It works better, right out of the box, then the Demon did after a year of futzing around. Now don't get me wrong, if you have a Demon and you like it, great. I may have just gotten a lemon. It's just that a Demon, like a Holly, is also considered to be a high performance carb and somehow superior to an Edelbrock. They are not. The design may be great, but the quality of the one I got was awfull.
 
#16 ·
Great info guys, thank you, but you must know, I'm not a high tech carb guy, so with all the info I gave on here about the carb theories was stuff I was told from other people. Right or wrong I have no idea! I think the performance shop guy I talked about told me to get the holley 770 instead of working the 1406 edelbrock, was the best way for a person like me to rectify the stumble problem in my car. But according to Edelbrock, the 1406 is a "economy carb" which I believe in just the name alone, its not the carb for me. My stroker wants fuel at will:) So my 770 is here, but it is the MN fishing opener this weekend so I wont be putting it on. When I get it on, I will let you guys know the difference, thank you for all the great comments. By the way, anyone want to buy a great performing 1406 Edelbrock carb, like new, with a performer intake. Jeff
 
#17 ·
i ran that 600cfm on a 388 stroker with an auto and rpm intake 2200stall and it would twist to 6700rpm that was the sweet spot..ported 624 castings 1.94-1.60..and it would pull the left front wheel an inch

DO THIS TEST.. car in neutral loosen the metering rod cover screws, maybe 3.5 turns the piston will push up the cover ,but not come out

now start the engine they should suck down. and stay down..
Blip the throttle they should come up and hit the cover..blip it repetitevly quick like, they should come up and down following the throttle...

for best performance RUN THE HEAVIEST SPRING YOU CAN under the power piston.. I usually run the old 60's afb springs with an INK PEN spring to make it even stiffer....

Too stiff and the power piston at idle will not stay down...find that spot and you will need to go softer on the spring

That my friends will make your AFB type carb come into the primary power circuit extremely well....

Make sure the squirters are squirting as you blip.. or you have another problem to fix
 
#21 ·
I have personally run both the 1406 and 1407 Edelbrock carbs on a decent 402 BBC on top of a RPM Air Gap intake. Between the two for street manners I actually prefer the smaller carb. The issue with the 750 is that vacuum changes too fast as you start to open the throttle. When vacuum drops below 5-7" the idle circuit shuts off and you have bog city. Plus I had serious challenges getting the secondaries to provide enough fuel.

The 1406 is slightly spreadbore and has a much smoother vacuum transition. It also pulls fuel better on the secondaries.

I would make sure you accelerator pump is setup correctly. You need the hole closest to the arm pivot AND you need to adjust it for a full stroke. Every time you move to a different hole you need to readjust the pump stroke on the Ede carbs.
 
#23 ·
I would make sure you accelerator pump is setup correctly. You need the hole closest to the arm pivot AND you need to adjust it for a full stroke. Every time you move to a different hole you need to readjust the pump stroke on the Ede carbs.
What do you do to do that, bend the rod or the arm itself?
 
#25 ·
WOW, way to complicated for me, like I said from the start, carbs are not my gig. So I will try the swap and hopefully that cures the problem for a carb dummy like me. Thanks for all the great info, I wish I knew this stuff, and I wish I understood some of it! Thanks again, all, Jeff
 
#27 ·
I just purchased a Speed Demon 650 over the Edelbrock 650 Thunder AVS because I read the Edelbrock carbs were made for camshafts up to a 220 @ 0.50% lift duration and the Speed Demon 650 is for durations of 220 to 250 @ 0.50% my cam shaft is in the 230-236 range anybody have any suggestions if that was the right purchase? Im replacing a worn out Edelbrock 1406 w/ electric choke 600 cfm.
 
#28 ·
the numbers from the rods can be deciphered in the manual on the calibration page. with my eddy i messed with the springs for the primarys and it made a huge difference. have you had the top of the carb off? if so i would make sure the rods are in the jets. i made this mistake, went to drive it and it bogged hard. also there are two vacuum ports on the front and when i had mine on the right hand side (looking straight at it from the front) it didnt like it one bit. other than that i would just play with the adjustment screws and feel the motor out on what it wants
 
#29 ·
Ok, the verdict is in. The 770 cfm Holley corrected all the problems, no matter which way anyone worded it, stumble, power loss etc................. I bolted it on, the dual feed line leaked took it off, put it on, it leaked again, took it off, looked it over, nothing obvious, put it on, and no more leaks, did all the Holley adjustments they said to do on their DVD, which was great, went and ran it, it is a whole new car, unbelievable difference, very happy now, with no stumble, Jeff
 
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