Carb advice?

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Mopar to ya

Mopar to ya

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I have an Edelbrock 1406 600 cfm carb on my Dart right now. It runs and idles beautifully. It is adjusted very well, but the mixture screws are way out. When I floor it it immediately winds up, I start to fishtail, and about when it begins to straighten out it starts to cough and sputter. I am guessing a lean backfire and thinking maybe the carb is too small, or maybe I need to re-jet it. I have no idea what the jets are now, I assume whatever came stock in the carb. I am looking at an Eddy 1413 800 cfm because I like my set up and it will bolt right in with all the same linkages. I am looking for advice, even though I can already sense the can opening and the worms sneaking out ... :)

73 Dart Sport
318
Edelbrock RPM air gap intake
Edelbrock 1406 600 cfm carb
Comp Cams XE268H cam and lifters
Hooker competition headers with 2 1/2" exhaust
Stock 904 with 2800 stall
Dana 60 with 4.10
 
Yup. It's too small. I think the 800 would be too much though.
 
I would have thought that carb would be good for 6000 rpm, which would be an area that cam wouldn't opperate too good in.
 
If you think the carb is too small, put a 1" square hole spacer underneath it.

The sputter could be a fuel delivery issue as well. If you are draining the bowls it will certainly lean out. Check your fuel pressure.

Since you indicate the idle screws are "way out" as well, start with the basics. Check the float settings. A low fuel level will lean out quick when you jump on it.

Re-jetting & tuning that carb is simple enough. You can download the manual from the edelbrock website.

B.
 
I will check the float level tomorrow morning. I don't have a fuel pressure gauge and will have to borrow one. I am running a stock mechanical fuel pump which puts out less pressure at WOT. I am just thinking that the 600 may be not enough at this point.
 
While you have the top off to set the floats, make a note of the jets & needles in it.

A 600 might lay down a little on the top end, but it should not go lean.

The 1" spacer will help the top end if you are short on cfm.

B.
 
Your idle set screw is too high, and your Air/Fuel screws are out to far.

You need to REzero that carb.

Set the timing with the vacuum hose unplugged...to the highest/steadiest vacuum reading.

Screw both Air/Fuel screws in all the way.
Back them out 1 1/2 turns from seated.
Set the idle to 800ish rpm

Adjust the choke to a light spring back on the choke door....stiffer for longer warm up.

THEN...turn the right side Air/Fuel screw IN till you hear the idle drop....and back out till you hear it increase....the ideal setting is in the middle of that.

Repeat for Left Side....Set Fast Idle to 1100, and idle to 800ish.

Done.
 
bohica2xo said:
If you think the carb is too small, put a 1" square hole spacer underneath it.

The sputter could be a fuel delivery issue as well. If you are draining the bowls it will certainly lean out. Check your fuel pressure.

Since you indicate the idle screws are "way out" as well, start with the basics. Check the float settings. A low fuel level will lean out quick when you jump on it.

Re-jetting & tuning that carb is simple enough. You can download the manual from the edelbrock website.

B.
Click to expand...
agreed,i was thinking float as well.
 
Prine said:
Your idle set screw is too high, and your Air/Fuel screws are out to far.

You need to REzero that carb.

Set the timing with the vacuum hose unplugged...to the highest/steadiest vacuum reading.

Screw both Air/Fuel screws in all the way.
Back them out 1 1/2 turns from seated.
Set the idle to 800ish rpm

Adjust the choke to a light spring back on the choke door....stiffer for longer warm up.

THEN...turn the right side Air/Fuel screw IN till you hear the idle drop....and back out till you hear it increase....the ideal setting is in the middle of that.

Repeat for Left Side....Set Fast Idle to 1100, and idle to 800ish.

Done.
Click to expand...

Already did all that. Didn't run well, lack of acceleration, hesitation on moderate to heavy accel. Idled nice, though. Took it to an experienced carb guy I know who works on all the rods in town. He adjusted the carb the way it is now and the car never ran this good. I don't think he took it out on a WOT run, though, so I am sure he didn't know about the problem. I am going to tell him and see what he thinks as well.
 
magnumdart said:
I would have thought that carb would be good for 6000 rpm, which would be an area that cam wouldn't opperate too good in.
Click to expand...

It would be....BUT, it has a lotta cam a lotta stall and a lotta gear for that little carb. Not to mention a monster of an intake. All those things can add up to needing a bigger carb, regardless of peak RPM.
 
The Eddy 1406 carb is an economy carby. The better carb is the 1405 which runs richer for modified street engines. I had the problem where the car surged and pinged at light to medium throttle. This indicated the carby was very lean. This was fixed by jetting up the primaries to step #19 from the carb manual and I also jetted up on e step in the secondaries aswell. You need to download the manual to see what I am talking about. The 600 is fantastic down low. Buy the jetting kit for this model and retune the carby under instruction of the manual. Don't put a bigger carb on the car. You will end up back to the 600.

Regards
BillyD...
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Billbo - Would a regulator be helpful if he was to upgrade to a bigger carb or would it still cause similar symptoms?
 
any carb you put on ...is going to be needed to be tuned to your combination and weather....


so buying a bigger carb is not going to solve your problem.....

i know some 340 barracudas that run pretty fast with stock avs carbs....
 
A regulator will not help. A regulator is fitted if you have too much fuel pressure. The 1406 600cfm carb is good to at least 5500 rpm for a 360 with the cam specs he has. The draw back with these carbs is that they run leaner in the idle mixtures than Holleys. This is why people cannot get the:

-off idle stumble out
-surging at very light throttle
-idle to main transition hesitation
out of the engine when they install these carbs on thier cars.
O.k. they do work right out of the box if you have an engine that can give a high signal (vacuum reading) at idle, but when you have a performance camshaft in your engine the 1405 carb is better and still might require modification.
I just found a solution to my 1406 problem. Although richening up the primaries helped with the surging, the idle to main transition was still no good no matter how rich you went in the primaries. The only solution is to richen the idle circuit. I know you guys are no going to like this but the idle jetting needs to be enlarged by a very small degree to get a smooth idle to main transistion and bring back drivability to the car.
So I will tell you what I did:
According to the carb manual I went to step #19 on main jets. This I reduced to step #23 but I also drilled out the idle jets in both main venturis from approximately 35 thou to 40 thou. I still needed one step richer jet in the primaries. Even the Q & A's on the edelbrock web site state this also. (I was still getting slight detonation at moderate throttle openings)
With the richer idle jetting and after readjusting the idle mixtures, The car has not felt so great with a Edelbrock carb. As people has mentioned before they threw thier eddeys away and have gone to Holley. I was one of these people.
I have tried:
-Carter 625cfm
-Carter 750cfm
-and this 1406 Eddy
and they ALL had the same caracteristic!
I was very reluctant to drill the previous carbs so I stayed with Holley with good results. But I was so desperate to get this one right.
I like the carter design. It starts easier and idles smoother with a radical cam spec.
I would recomend to drill VERY CARFULLY the idle jets 2 thou at a time and test the outcome. You will need to get one or more precision drills from a machine shop or somewhere else who might have these drills.
My engine is a 360 with a Comp cams xe274H, 10.4:1 with LD4B maifold and the eddy 1406 with mods.
So far so good.
Soory for the long story.
Hope this helps.

Regards
Billy D...
***************************************
 
:prayer: Very helpful info, Billbo.

I'm just getting introduced into the "Fine Details of The Carb World" and I've heard so much about all brands. I've recently picked up a Edelbrock 1407 for my 318. It's a work in progress. I've upgraded the ignition system and my next step is the heads and cam. Hopefully, I'll have positive results.
 
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