edelbrock 1406, running way rich, how do i tune them?

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magnumdust

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I just got my car back together from the power steering box nightmare and now i'm ready to tackle the next problem with my car. It is running incredibly rich. I pulled the plugs while sealing the header and found that in less than 10 miles the spark plugs were dark black and on their way to being completely fouled and of course the car feels rather gutless along with a stumble any time you get on the gas

Setup:
Magnum 360 w/ iron ram 1.90 heads, custom ground cam(i can dig up the specs if need be), crosswinds air-gap knockoff intake, hedman headers, and edelbrock 1406 carb.

Fueling is done by a Summit electric pump w/ a 5.5psi deadhead regulator. Though i made the mistake of running without a regulator at 7psi when i first got the car together. Is 7 psi enough to damage something in my carb?

Timing is 16/18 intial, 34/36 total(blanking on where i set the initial, but its one of those)

The carb is what came with my car when i bought it so i have no clue on its overall condition or if its even been tuned/rebuilt.

So where do i start??
 
You can download the user's manual from the Edelbrock website. It has a lot of useful information about how the carb works and how to tune it.
 
heres the link [ame]http://www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf[/ame]
 
Start by chking your float levels and fuel inlet needle and seat.
Pull the jets (really easy to do) and see what the sizes are compared to what the carb originally came with.
Unless someone put really huge jets in that thing I can't imagine why it would be running that rich otherwise.
I dropped a 1406 on my 318 and had to up the main and secondary jets 2 sizes just to get enough fuel.
This is why I think you may have a float level or needle and seat issue.
 
This is the area in the carb to deal with if you have to change needles and jets.
The online manual is a little confusing but you can see the basics of the metering in this pic.
 

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Try turning fuel pressure down to 5-5.5 max.

Check float level.
 
All of the above.

What sort of cam do you run?

Are you sure the carb is clean, not all gummed up inside?

Has someone before you (used carb?) been "into" the thing diddling with the metering rods and jets?

You might have "junk" in one or both needles, causing fuel to leak past. Can you hold the throttle at some RPM, and look down the carb throat? Do you hear or see fuel siphoning over into the throat? This makes an erratic popping sound sort of like bacon frying.

Too high fuel pressure

Floats damaged

Floats set too high

Needle/ seats damaged/ dirty

Carb is dirty/ gummed up, metering rods stuck

Carb has been "effed with" by previous owner
 
try a fatter rod. that leans it. the idle screws should be baselined at 1.5 out then set idle. Warm motor: turn one side to get max rpm, then reset idle speed then adjust the other for max rpm, then reset idle again. then trim both in until you get just a hint of a drop in RPM, there you go. Now try fatter rods. The rods do not effect idle. Also make sure your rods are fully sunk at idle. You can turn out rod covers so you can see the rod carriers in their bores. At idle they should be down, and not bouncing. If they are up or you can push them down more manually then your rod springs are too heavy, lighten up with different springs. Its nice to have a good tach and vacuum gauge for this. [ame]http://www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf[/ame]
 
67Dart273 said:
All of the above.

What sort of cam do you run?

Are you sure the carb is clean, not all gummed up inside?

Has someone before you (used carb?) been "into" the thing diddling with the metering rods and jets?

You might have "junk" in one or both needles, causing fuel to leak past. Can you hold the throttle at some RPM, and look down the carb throat? Do you hear or see fuel siphoning over into the throat? This makes an erratic popping sound sort of like bacon frying.

Too high fuel pressure

Floats damaged

Floats set too high

Needle/ seats damaged/ dirty

Carb is dirty/ gummed up, metering rods stuck

Carb has been "effed with" by previous owner
Click to expand...

Given that virtually every project on my car has had a moment of "WTF was that last owner thinking" its very possible that the previous owner played with something on the carb or that the carb was just a pile of junk, like the rest of the old engine.

Crackedback- it is down to 5.5psi now and still running this rich.

Below is the pic of the little cam-specs card that came with the cam. The engine has the factory style 1.6 rockers.

So, right now i guess maybe the first step might be to rebuild the carb to make sure everything is actually functioning and go from there?
 

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You got some good info from some of the guys. Larger cams can greatly affect idle vacuum. If vacuum is too low, the metering rod pistons will not come into play to restrict the jet orifice by the metering rod and so it runs rich. The hesitation you feel is when the throttle is hit, it gets an instant vacuum "shock" and it goes lean for that split instant but then goes back to rich. It appears you need lighter springs or fatter metering rods. Check float level by holding the removed carb top upside down. If the floats are parallel to the gasket you should be good to go. NEVER run more than 5 lbs of fuel pressure with these carbs. Even 5.5 will allow GRADUAL flooding! I've been doing carbs for over 50-years and I don't think one problem ever possible didn't happen to me! LOL! I'm not putting down the Eddy carbs but this is why I always recommend a Holley for applications with vacuum reducing cams. Nobody seems to respect the lowly vacuum gage these days! The power valve in a Holley carb does what the metering rods and springs do in Eddy/Carter-type carbs. The advantage is that the Holley power valves are numbered to relate to you engine's actual vacuum reading. Let's say you got a Holley List 4777 650 cfm double pumper. It will come out of the box with a power valve marked 6.5. This means that it will remain closed and restrict fuel to the power circuit until vacuum drops to 6.5 hg. Therefore, a lower number power valve is leaner. A 10.5 will be much richer. If your engine with custom cam has 17 hg of vacuum at idle, or higher, a 65 power valve will be beneficial. Watch that vacuum gage drop when you gas it! It is so much easier to tune a Holley to vacuum than a Carter/Edelbrock. The lowly vacuum gage will also tell you if the carb is sized right for your engine. If the gage reads zero or very near it at WFO, the carb is at max volumetric efficiency. Hope I helped and didn't confuse.
Pat
 
Previous owners :banghead: no telling what you have until you check it out. Remove the jets and metering rods and write the numbers down that are stamped on ALL of them. Refer to the Eddy tuning guide that was already posted earlier and this will tell you exactly where you are. It might help to post the info here too. And since you don't know what has been done before, take the time and go through the little adjustments. Float height probably being most critical. IIRC, that's all covered pretty well in a 60's era Mopar servece manual since it is basically a Carter AFB.

I'm running a 625 Carter AFB (1406 Eddy) on a 318. Using the tuning guide I was able to get it running pretty well in spite of the previous owners "adjustments". I bought a strip kit from Summit and it included 5 sets of springs and an assortment of jets and rods. Using that and the tuning guide, all 8 plugs are text book perfect now. Best I've ever seen on any car I've owned.
 
Check the floats. I had a 1406 with a leaky one.
 
Ok so update:

I did the full rebuild today and to my surprise, i didnt screw it up. lol, well atleast not totally. I had expected that i would screw up badly, and be buying a holley on tuesday.

Anyways things i found once inside the carb:
1. Nasty carbon deposits everywhere. Two cans of carb cleaner and it was good as new.
2. Floats were way off the appropriate adjustment range for both the drop/level
3. A metering rod was bent and sticking. Now bent might be on me because i made a newbie disassembly error, but i was never rough/forceful with the top plate. So i suspect the sticking/bend was there beforehand.
4. The floats appear to have a slow leak. They didnt sink, but the floated *** heavy and given enough time i think they would've sank.

So replaced the busted parts, cleaned everything, set the base adjustments per. the instruction sheet, and installed it along with a new set of spark plugs. It fired up instantly and sounded healthier than ever. There wasnt the annoying bog that the car use to have when it was cold.
 
If anything a stock 1406, shoud be way lean , i had to buy a calibration kit and up mine with jets and rods. on a stock 73 340
 
I'm still struggling with some carb issues. Yesterday my calibration kit came in and i swapped out the metering rods to the .70x.37 which with the stock jets is suppose to give the richest mixture w/ the stock jets and calibration kit.

The engine is still running pretty lean. I went to the middle of nowhere and did a few WOT starts and then checked the plugs. There doesnt appear to be any hint of brown on the porcelean and on the side electrode(curved metal piece) the metal looks to have some heat discoloration.

I richened the idle mixture to 2 1/2 turns out, changed the springs to orange springs, and set the fuel regulator at 5.5psi(was at 5psi) and still the same results.

Timing is still at the same 16-18 initial and 34-36 total.

Also, it occasionally diesels(briefly) when i turn the car off.
 
Sounds like a manifold vaccumn leak. My 440 does that too because the machine shop didnt mill the intake face on the heads when i had them milled. Gonna have to pull the intake and have it milled instead. Did you have trouble bolting down the intake?
 
You might also consider installing the ubiquitous Bosch oxygen sensor into your exhaust system and running a digital gauge (Innovate or other) somewhere easily visible. I spent $100 on my mine. With this setup and a little graph paper, it makes your carb, timing, and distributor calibrations an enjoyable process.

I have an Edelbrock 1406 on my 360 and it's great, even though I'm getting ready to do an EFI conversion. With the air/fuel gauge you really, really know what values you're getting at all times. Even with a range of 4-5 different rods and springs the car will sound like its running perfectly fine. But to really dial it in you need good feedback that you simply cannot detect by listening and plug reading alone. The other information the air/fuel gauge shows is how a carburetor is only in the ballpark most of the time. It's really only dead on target at idle, mid throttle, or full throttle with the secondaries open. In the transitions you just want to make sure that it isn't starved or dumping fuel. I have mine dialed where I'm always between 13.5-14.5 regardless of conditions, which is the best you can hope for.

So buy one the Edelbrock carb tuning kits and prepare to pick up a couple of extra sets of rods. The kit contains a range of jets and springs, but doubtfully the exact rods you need.

As the above poster mentions, if you're getting sudden unexpected gunning throttle you probably have a vacuum leak. You'll obviously have to take care of that first.

It's worth it.

-marcus
 
Don't try to tune anything but "curb idle" with the mixture screws.

The rest is a combo of jets, rods, and springs.
 
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