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another Eddy 1406 sob story

A

aceinco

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I know I'm going to get blasted for this, but I'm doing it anyway!

I've spent countless hours scouring countless posts on dozens of forums and read countless articles trying to nail this one down to no avail. so, I thought I'd turn to the members of this board for my query. I'm sure this question has been answered many times over and over again but I just can't seem to find it... so...

I have a 78 K5 with a 350 SB and TH350 trans, stock NP203 and stock 10 bolt / 12 bolt axles... when I bought it last fall I drove it home but almost stopped to call a tow truck, it was that scary to drive (and I've driven a lot of junk over the decades!)... I have since replaced every single component of the service braking system and the cooling system, deleting the O.E. cooling fan, opting for an electric fan... this thing sits steady all day long at 190*F... I replaced the stock exhaust with a set of Hooker headers, 2 1/2" pipes, and a pair of Flowmaster 40 mufflers... the lady I bought it from removed the original Q-jet and installed an Edelbrock 1406 in its place... the install was... rough... to say the least... the O.E. gas tank had about 2 gallons of water and about 10lbs of rust in it so I replaced it with a 32gal fuel cell, all new fuel lines, and an electric pump, regulated to 4.5psi with a new Holley regulator... a new Weiand dual plane intake... I replaced the cam with a Comp Cams 12-231-2 cam kit (lifters included) 206/214 duration at .050" and .432/.453 lift... new timing gear set from Comp, also... broke in the cam at 2500rpm for 1/2 hour with Joe Gibbs break-in oil and replaced after break-in with Joe Gibbs 10w-30 and new WIX filter... I installed a new mechanical advance kit from MSD with the lightest springs in the kit and a new Accell vacuum advance... I have initial timing set about 12-14* and total timing at about 40* coming in about 2500rpm... intake vacuum is steady at about 16" hg, no surprises revving it up or decelerating... it runs very smooth (mostly)... new cap, rotor, wires, plugs... everything needed to make this beauty purr, BUT...

it'll sit and purr like a kitten in the driveway... I can rev it up and it's smooth all the way to 4500rpm... but, as soon as I try to drive it, everything goes to pot! when I shift into gear the revs drop by about 500rpm... I live in the middle of a decent sized hill, about a half mile from the bottom and about one mile to the top... I always drive to the top of the hill and by the time I get there, the engine seems to be loaded up full of gas and won't run properly... I have to shift to neutral and rev the snot out of it before I can go anywhere... #8 plug keeps fouling to the point where I've had to replace it... I know the Edelbrock owners manual is available on-line and I've downloaded it and read through it several times... I've used the charts to lean it out step-by-step and have gone out of range on the chart... I'm continually tuning this thing leaner and leaner and I've not yet hit the "lean stumble" I've expected to experience... :dunno:

I talked to a guy at a local parts store and he says folks using that carb are leaning it WAY down with great results... right now I have .092 primary and .089 secondary with 75-47 metering rods and the 3" (lightest... blue) step-up springs installed... this guy was saying he's seen people regularly use .080 primaries and secondaries with the 73-47 rods and 4"springs on 500+ HP engines:eek1: ... does this sound right to anyone??? I live at 6200 feet above sea level, but I've seen much richer combos than this described all over the internet even at this elevation and they claim to be working well... anybody got any ideas?
 
some years back i fooled around with those carbs, i dont remember how it was jetted but it ran great.
i had a problem with it running rich and it was due to the float bouncing around, i installed the spring loaded needle and seat kit,
you could also lower the float level temporarly to see if that helps
 
I also installed the offroad needles and it runs much better now. Im honestly quite happy with my 1406. It can sit on a steep hill all day long and not sputter out. Also make sure your floats... Float. Take them and place in a bowl of water, and make sure they stay up. Could have a bad one
 
I bought the rebuild kit(edelbrock #1477), new floats(#1469),new electric choke(dont have package), and offroad needles (#1465) from summit, had it to my door in 2 days and i dont think it was very costly. I also found a REALLY good book on amazon for $10 on these carbs. Tons of pictures and step by step rebuild directions with pics and captions. Along with tons of other great info. Book is by HP BOOKS, Larry Shepard - Rebuild & Powertune - Carter/Edelbrock Carburetours.
 
I feel your pain. I have gone round and round with mine. I live at 7000 feet. I have jetted down several carbs. My experience is most people think they need way more fuel than they really need. You can only ad as much fuel as you have air. At these altitudes it isn't much. I think in mine I am running 82 and 85's? If I remember right. I ran into vapor lock issues this summer with mine so I went to TBI. Where in Co are you maybe I can help.
 
i would say to start your timing is way high i usually dont like more than 36 total on good gas.

have you pulled the valve covers to make sure everything is opening closing properly? flat cam maybe?
 
I did a few mods to mine and it worked pretty damn good. I had a write up on it but cannot find it on my iPad.
 
a 4779 is a holley 750 double pumper. They don't have them at autozone.
 
first, I would like to say thanks for all the replies... the videos were very informative, and all the advice appreciated...

I think I got it figured out... I called a few reputable shops in the area asking for advice... mostly I got the same old schtick as usual (check all your settings, use the Edelbrock manual, etc.) but one guy I talked to had a slightly different take on it... he told me to remove my choke flap and run it like that... when I got home I went through the carb, checked the choke settings and noticed when I'm on the gas it's a little sloppy... I changed the jets to VERY lean and removed the choke plate... started it up and got a nice lean-stumble just off throttle (finally!)... rejetted until the lean stumble was gone and drove it...

I still have a slight lean stumble at about 50% throttle angle but no more loading up, no more falling flat on it's face, no more stalling out!!! the choke plate slop must have been causing all my problems...

right now I have a .086 primary with 70-47 metering rods, 5" (orange) step-up springs, and a .083 secondary... I'm going to try a slightly smaller rod next then go from there...

I feel kinda foolish for not thinking of this myself, but when you're that close to a problem, solutions, even simple or obvious ones, can be quite elusive... sometimes it's best to get an outside opinion and some fresh perspectives:rolleyes:

thanks again for everyone that chimed in... I really appreciate it!
 
fresh eyes/ears can help find a lot of problems....:waytogo:
 
Once the 1406 is dialed in you will be happy. They ate stupid simple carbs and work good for a long time once turned in. The 1406 is rated for 600 cfm, but actually flows in the 550s. Which is good for.Colorado altitude.

One thing I started doing with these carbs is run the wood edelbrock carb spacer to help.dissipate heat from the intake to the carb. The way the bowls are part of the side. They don't cool the fuel very well and that series or carbs tends to heat the fuel up.
 
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