Edelbrock 1406 600 cfm Carb a little rich, how do I adjust [Archive] - Team Camaro Tech

: Edelbrock 1406 600 cfm Carb a little rich, how do I adjust


Buildinga55
May 31st, 06, 07:13 AM
I have a 600cfm Edelbrock 1406 carb on my 350. Have the HEI installed and it is running pretty good. It does seem to be a little rich however. I am not a carb guy. This carb is new. Is there a simple screw adjustment to lean the carb out a little without screwing something up? If this were an 8N Ford tractor, that is about my speed when it comes to carbs.

kz1000ltd
May 31st, 06, 07:34 AM
No, you need to lower your jet size, very simple process on these carbs, but you have to have the calibration kit, available at Jegs or Summit. Then, all you do is take the top off of the carb (easier to do off the car, but can be done while still attached to the intake). The jets are just screws that come out, and you replace it was a smaller one, so it gets less gas. There are 4 total, 2 on the primary side and 2 on the secondary. The calibration kit comes with instructions, very good investment, it also includes step up springs and some other doo dads (metering rods)! :beers:

Everett#2390
May 31st, 06, 07:37 AM
There are two mixture screws on the front pointing up. These screws along with a vacuum gauge, can be used to adjust the mixture for the best running, meaning the higher the vacuum reading, the better.

I have one on Buford (black 88 Monte Carlo SS) atop a 307 w/HEI, and it pulls 17 in./Hg at 750 rpm. I have about 10* BTDC of initial.

Other than that, that's about it. Unless you want to buy a tune-up kit for it and change jets and metering rods, very easy to do. And the nice part about it you can go back to where you started.

go2fast
May 31st, 06, 07:52 AM
There are two mixture screws on the front pointing up. These screws along with a vacuum gauge, can be used to adjust the mixture for the best running, meaning the higher the vacuum reading, the better.

I have one on Buford (black 88 Monte Carlo SS) atop a 307 w/HEI, and it pulls 17 in./Hg at 750 rpm. I have about 10* BTDC of initial.

Other than that, that's about it. Unless you want to buy a tune-up kit for it and change jets and metering rods, very easy to do. And the nice part about it you can go back to where you started.

Note that the screws adjust idle mixture only. Is it rich at idle or rich when off idle? Does the motor have a performance cam?

STM69
May 31st, 06, 12:16 PM
I have this carb. Check the back of the manual. It has tuning graphs in the back of the book. Or go here:
http://www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf
and slide your side bar down to the middle (Pg 13. of 26). Check the graph for the 1406 and look in the middle of the graph. That is #1, which the calibration that it comes out of the box. If you look below the graph, you'll see that #1 has a .098 main jet and a .075 x .047 metering rod. This rod and jet together create a certain air/fuel mixture. Chnaging these (by changing numbers on the chart will get you leaner. Try number 7 and then go 1 step leaner in your secondarys too. (which would be a .092 jet) that should get you close. When you check out this graph and study it for a little bit, you'll see that this is a stupid easy carb. just a note... #1 setting was way too rich fpr me with 195cc fairly high flowing heads and an RPM manifold... dont know why...

smalblock
May 31st, 06, 12:26 PM
You don't have to remove the carb. from the intake manifold or remove the carb. top. Remove the metering rods and replace with the next larger size found in the calibration kit. On a 350 motor, you should be able to tune it for street use without changing the jets. Jack

Buildinga55
May 31st, 06, 12:40 PM
The car is a 4 speed. Seems like it is rich at idle and when you rev up to take off in first. Also, after you turn the car off and let it sit a little while, it seems to be flooded when you first start the car. Seems to run pretty good once you get going. I may still be rich. I have not driven the car much yet as I have not had the car in the front end shop for an alignment. Just trying to get it running pretty good so I can drive it to town.

STM69
May 31st, 06, 01:10 PM
Check the plugs at idle, check them after cruising at mid RPMs by shutting it down at 3000RPM to not let the car go back to idle before you turn off the ignition. And, try WOT. You don't need to take the carb off, but just changing the metering rod over and over won't show you where you are on the graph which is really handy. Its worth the 5min. to remove the top,in my opinion. Also, on the accelerator pump (front of carb on drivers side) there is a 3 hole bracket that attaches to the throttle linkage... which hole is the linkage using? The closer to the top, the more fuel is supplied at take off.

JimM
May 31st, 06, 03:32 PM
If this is a new carb, you'd best check the float levels before you make any other changes.
And yes, the top has to come off to do that. It's easy to do.

go2fast
May 31st, 06, 04:45 PM
The car is a 4 speed. Seems like it is rich at idle and when you rev up to take off in first. Also, after you turn the car off and let it sit a little while, it seems to be flooded when you first start the car. Seems to run pretty good once you get going. I may still be rich. I have not driven the car much yet as I have not had the car in the front end shop for an alignment. Just trying to get it running pretty good so I can drive it to town.

If it's flooding when you shut it off hot, it may be percolating. You may need an insulating (thicker) gasket under it.

Steptoe
May 31st, 06, 11:09 PM
A word of warning before determining if It ACTUALLY is running rich.
If u have headers and/or upped the cam a bit, it may read rich at the exhuast but run lean in the engine..
Just before the inlet opens, there is a slightly more concentated 'pool' of mixture on top of it. both valves are open at the same time, and the length of that time and/or scavanging effect of headers, will pull this 'pool' right thru into the exhaust as raw mixture.
Determine a rich run, by reading spark plugs...make a good run of several miles, kill the engine pull and read the plugs.
There is many a good engine killed by running to lean, and blamed on cams, machining or anything else that has nothing to do with the owner.
In saying that..Carb manufactures tend to over jet a couple sizes up..the reason is if the carb is sloightly rich, engine dies, it cant be blamed on a lean carb and saves on expensive lawyers

Buildinga55
Jun 1st, 06, 11:50 AM
Thanks for everyones advise. The car does not have headers, but does have a very mild cam. I will drive the car this weekend 50 miles or so and pull the plugs before doing anything else. It sounds like that should give me a pretty accurate reading of a rich condition or not. Then I can determine if anything needs to be done. Thanks

ept000
Jun 1st, 06, 12:26 PM
The restart is common on the Edelbrock carb. There have been lots of posts here about it.

Granny's 69
Jun 1st, 06, 09:12 PM
If this is a new carb, you'd best check the float levels before you make any other changes.
And yes, the top has to come off to do that. It's easy to do.

I'm having the same running rich problem on my E-Brock 1406. As JimM said above, I pulled the top off the carb and the floats were way out of adjustment. Per the E-Brock manual, the proper float level is 7/16" with the airhorn inverted and 1" max of float drop with the airhorn upright.