Edelbrock 1405 or 1406? (Off road mod)

[Airmapper]

I probably shouldn't start messing with it, if it ain't broke and all......

It's well known that Edelbrocks are crap off road, and I think I'm starting to see this some. Turning around I took it off the pavement, I noticed it was quick to die if I tried to goose it a little and I wasn't level. Kinda annoying.

The goal for my '70 is off road capable, so I want to try this modification someone (73stallion maybe?) sent me some info on. (I uploaded it to my drive LINK) Nothing to loose except maybe $12 for spring needles if it doesn't work.

So now my question is, should I try this little experiment on my 1405 or 1406? The 1406 is on the '70 now, I rebuilt it and it's running great, tap the key and it starts, almost hate to touch it.

I got the 1405 at a yard sale, haven't tried it but I rebuilt it as well. Looked great inside, should be like a new one.

So which one should I try this experiment on? The 1405 is billed as more "performance" oriented, and the 1406 as more "economy." I know very little about tuning a carb so I don't know what that means. Any ideas?

 

[needabronco]

I had an 1826 and it ran better out of the box off road than my brother in laws off road holley!

 

[nrramse]

I put the offroad springs in my 1404, which I think is like your 1406 but has a manual choke instead of automatic. It will still stall if I descend something both steep and bouncy - which is not very often for me so I'm good with it. I've heard of guys lowering the float level for improvement but I've not tried it.

 

[br0nc0xrapt0r]

Q-jet, nuff said.

 

[gr8scott]

I had an 1826 and it ran better out of the box off road than my brother in laws off road holley!

I've been running an 1825 for a few years now and have'nt had any carb stumble going up or down long steep
hills or even off canter.

My 1405 would stumble going up short hills...

I would say modify the 1405 with the off road needles and seats:
http://www.summitracing.com/parts/EDL-1465/

 

[DirtDonk]

Me too. Like you, I hate to mess with something that's running good. But in this case, it's on the truck, you've already seen how it works with just a little bumping around, and it would give you the quickest test.
Since you just have to pop the top and don't have to remove the whole carb, it should be pretty straightforward. And it will be the most direct comparison.

Paul

 

[broncnaz]

your not changing the tuning any just replacing needle seats so it shouldnt change the way your engine runs at all.

 

[jms5580]

Q-jet, nuff said.

Amen! Can't wait to test mine out.

 

[John Marinan]

If this works you'll make a whole lot of people with Edelbrocks, or contemplating using one, very happy!

 

[Airmapper]

Me too. Like you, I hate to mess with something that's running good. But in this case, it's on the truck, you've already seen how it works with just a little bumping around, and it would give you the quickest test.
Since you just have to pop the top and don't have to remove the whole carb, it should be pretty straightforward. And it will be the most direct comparison.

Paul

This is good logic, I'm leaning this way as I won't have to mess with as much. I know that carb fairly well now, I can put it back and I don't intend to use anything permanent to block the bowl passage.

If this works you'll make a whole lot of people with Edelbrocks, or contemplating using one, very happy!

That's mostly why I'm planning on this. I got all the stuff, why not try it. If it's junk off road still, I can sell the Edelbrocks and go Q-Jet.

Some of my curiosity was what is different between the 2 carbs? They are tuned differently, but I'm not sure I understand how that makes that much difference. If the 1405 sucks any more gas than a 1406 I need a wagon full of gas to pull behind me. ;D I think it's getting all the gas it can handle now.

 

[COBlu77]

It's been a while since I ran a carb, but when I did it was a Carter AFB (same as the Edelbrock). To make it run off-road I used the "offroad" needle and seat, raised the float level slightly, used a 1/2" phenolic spacer, but the real thing that would keep it from stumbling in the rough stuff was a cheap Purolator dial adjusted fuel pressure regulator. I would turn it down to 2 psi when I turned my hubs and no more loading up or dying. I'd put it back to 6 when I hit the pavement. Bouncing and weird angles would allow the fuel pressure to mommentarily push open the needle/seat and flood it slightly, which is why they stumble and run rich offroad.

The combination of ethanol, high altitude, heat and offroad gave my AFB fits until I did those things. It ran so well offroad and on, that my friends thought I was nuts to go EFI.

 

[jms5580]

It's been a while since I ran a carb, but when I did it was a Carter AFB (same as the Edelbrock). To make it run off-road I used the "offroad" needle and seat, raised the float level slightly, used a 1/2" phenolic spacer, but the real thing that would keep it from stumbling in the rough stuff was a cheap Purolator dial adjusted fuel pressure regulator. I would turn it down to 2 psi when I turned my hubs and no more loading up or dying. I'd put it back to 6 when I hit the pavement. Bouncing and weird angles would allow the fuel pressure to mommentarily push open the needle/seat and flood it slightly, which is why they stumble and run rich offroad.

The combination of ethanol, high altitude, heat and offroad gave my AFB fits until I did those things. It ran so well offroad and on, that my friends thought I was nuts to go EFI.

Interesting concept with the regulator. I'll have to keep that one in mind. I know I always had issues when things got bumpy.

 

[carmi]

As stated, the offroad needle and seat should cause no changes to the carb settings. Adjust the float level per the manual and call it good. If you are having problems when you accelerate then try moving the accelator pump linkage to the lower holes. This will squirt less fuel when you push the accelerator. A fuel pressure regulator is essential to maintain the proper 5 psi and minimize flooding. I use an adjustable one and have had good luck turning it down to about 3 psi to help in off camber situations. Just crank it back up when you get off the trail. What I found is that the edelbrocks tend to run very rich from the factory. Look at the manual and lean out the carb a few steps with a change in needle and jets to see if it makes it more responsive. Try experimenting with the vaccuum springs. I had good luck leaning out the carb several steps while running the pink spring. That being said, After running a 1406 for 15 years, I finally made the switch to a SMI QJet and couldn't be happier.

 

[Airmapper]

Yesterday I tried to flood it off camber, but it ran fine. Maybe I didn't lean it far enough but I got the drivers side up on a bank and tipped it over far as I dared, but I'm a noob off road, so I didn't push it too far, probably 30 degrees, maybe little more. I was lifting the rear wheel and getting uncomfortable with it bobbing around, so I quit while I was ahead, didn't have anyone around to spot me.

I'll probably play with it some more to get an idea what I'm working with now, that way if I make changes I'll see if it improves. I need to try up and down angles next.

I do have the fuel pressure regulator, bowls set to factory specs, but no needle springs or bowl cross feed blocked.

I'm probably going to order the spring needles and a tuning kit soon. I think I'll try it a few stages lean and see what it does. I have noticed the throttle is kind off or on. You start to press and it goes from idle to revving up rather quickly, not much in between.

 

[OneRaceOneWinnr]

I have a 1411 (1407 with electronic choke) 750 cfm on a 351W with high rise Weiand Stealth intake and also headers. I do not have the offroad kit for the Edelbrock (just a stock 1411). I ran a few hills at my local offroad park (Spring Creek Offroad in Houston, TX). There are some really steep hills where I would flood out going up and down everytime like clock work. I broke the rules of scientific investigation and I changed two variables at the same time (so I don't know which one is what worked).

#1 I added a fuel pressure regulator and set it to 5.5 psi
#2 I added a copper vent tube extension (just like the Holley Truck Avenger). The vent openings in the carb aren't round like the tube so I filled in around the tube with steel putty.

I have never stalled due to inclination ever again off road and I've run exactly the same hills I did before I made the modifications. I've been running this setup for about 4 years.

The Edelbrock 1411 was put on by the previous owner. I believe it is too large for my engine.

I want to float the following carb sizing guidance. This is based on a stock engine with low restrictive exhaust and intake.

600 cfm ~ 300 ci displacement
650 cfm ~ 350 ci displacement
700 cfm ~ 400 ci displacement
750 cfm ~ 450 ci displacement

From my research and limited experience this makes sense to me.

 

[blubuckaroo]

I have a 1411 (1407 with electronic choke) 750 cfm on a 351W with high rise Weiand Stealth intake and also headers. I do not have the offroad kit for the Edelbrock (just a stock 1411). I ran a few hills at my local offroad park (Spring Creek Offroad in Houston, TX). There are some really steep hills where I would flood out going up and down everytime like clock work. I broke the rules of scientific investigation and I changed two variables at the same time (so I don't know which one is what worked).

#1 I added a fuel pressure regulator and set it to 5.5 psi
#2 I added a copper vent tube extension (just like the Holley Truck Avenger). The vent openings in the carb aren't round like the tube so I filled in around the tube with steel putty.

I have never stalled due to inclination ever again off road and I've run exactly the same hills I did before I made the modifications. I've been running this setup for about 4 years.

The Edelbrock 1411 was put on by the previous owner. I believe it is too large for my engine.

I want to float the following carb sizing guidance. This is based on a stock engine with low restrictive exhaust and intake.

600 cfm ~ 300 ci displacement
650 cfm ~ 350 ci displacement
700 cfm ~ 400 ci displacement
750 cfm ~ 450 ci displacement

From my research and limited experience this makes sense to me.

I agree with your carb mods. Edelbrock carbs seem to be affected by excessive fuel pressure than other carbs. I have a Cagle regulator that keeps the pressure around 2 PSI at idle. That and a slightly lowered float level have fixed my off-road issues. Your vent extension sure couldn't hurt either.
However...
I will debate your carb CFM / engine displacement guidance though. A 600 CFM would work great on say a Mustang & 302. However heavier cars need a lower CFM carb than a light car with the same motor displacement. I'd move your whole left column of CFM ratings one level. for a heavy car like a Bronco.