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Old 10-26-2005, 01:14 PM
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modifying that too rich edelbrock 1405 carb?

O.K. before putting this carb in the garbadge as few of you are going to suggest maybe I still can do something with that 600 cfm manual choke edelbrock carb..mayby some experts here could help?

This carb is on my 383 and since day one always had been too rich according an exhaust sensor,rich smell and black sparks..I've done my homeworks checking floats level,idle circuit adjusted decently,checking choke is open all the way,and most important tried about all combinations of jets/metering rods/springs available with no sensible ameliorations.

I was checking today the carb and trying to push open the secondaries plates I realised they offer a surprising resistance. Can it be that this create an air restriction making it a too rich mixture? I know the counterweights can be trimmed down ..should I look into this?

My usual driving is around 2800-3000 RPMs and the vacuum gauge then shows around 20 " HG. I think that is a lot and I kind of think that too much fuel is drawn in an not enough air...should I think about possibly drilling small holes into the primaries plate for more air? The 14X3 extreme air KN filter should not restric nothing here.

I am considering another carb (holley or whatever) but I keep reading so many complaints about too rich carbs. (holleys or whatever again!) that I feel like If I swap my actual edel. for something different all I'd end-up with is a new too rich carb. that I don't know nothing about how to tune (or try to do so!).
Please edelbrock knowledgeable fellows bring in your ideas.
thanks again,Ronald.

P.S. I had the exact same model carb. on a 289 ford with an edelbrock performer and my lugs were perfect tan...?!"/$

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Old 10-26-2005, 01:27 PM
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You have checked the fuel pressure? If the carb is too rich on a 383 something is wrong with it somewhere. The secondarys have no effect on the primary side. Many (myself included) chased this same problem too long before checking the fuel pressure and fining it was too high. Edel`s don`t like over 5 psi.
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Old 10-26-2005, 06:58 PM
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i've played with an edelbrock 1405 on a mild built ford 302 and found that the factory settings were way too rich too. i just bought a re-jet/re-rod kit for the carb from napa and used this chart to help choose which rods/jets to use. just make adjustments to either and monitor your a/f meter during idle, cruise, and w.o.t.

the chart:
http://www.edelbrock.com/automotive/eps_1405.html

for more information, here's some "light" reading you might consider
the owner's manual:
http://www.edelbrock.com/automotive/eps_intro.html
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Old 10-26-2005, 09:20 PM
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Edelbrock fuel dump

TVR383,DoubleVision is absolutely correct about the fuel pressure.AFB`s do not like pessures above 4-5lbs.Another factor to check is manifold vacuum at idle.Low vacuum camshafts create a need for a revised idle circuit.A 1405 AFB was designed as a basic replacement or a light performance carb.If you have a camshaft with a duration of 220 degrees or more at .050 lift, then you will never be able to correct the rich idle.If your camshaft is under these figures and fuel pressure is correct then start using the tuning guide that came with the carburetor.Good luck from rodderjohn.
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Old 10-27-2005, 07:31 AM
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Quote:
Originally Posted by rodder john
TVR383,DoubleVision is absolutely correct about the fuel pressure.AFB`s do not like pessures above 4-5lbs.Another factor to check is manifold vacuum at idle.Low vacuum camshafts create a need for a revised idle circuit.A 1405 AFB was designed as a basic replacement or a light performance carb.If you have a camshaft with a duration of 220 degrees or more at .050 lift, then you will never be able to correct the rich idle.If your camshaft is under these figures and fuel pressure is correct then start using the tuning guide that came with the carburetor.Good luck from rodderjohn.
John,

The pressure is kept aound 4-5 via a regulator. My cam is a 230 degrees...when you say the idle circuit will always be too rich with a cam over 220 does it mean I will be too rich at idle speed alone or all over the RPMs range?

According my o2 analyser ( its an old thing that could be done) after fiddling with the idle screws I'm OK at idle,altough it smells rich,but any range beyond shows too rich.BTW what I cannot understand is that trying all jets/rods/springs combos as per edelbrock's instructions (I had bought and tried many a times new jets/rods),even going to LEAN 10 or 12 % combo,my O2 will still indicate too rich ..so do the plugs indicate also! I might have merely ameliorate the O2 readings by one bar.

My sparks plugs after only 500 miles have some hardened black carbon deposits and I don't like the idea of seeing carbon deposits inside my recent rebuild 383. I have seen the oil level going down within the said maiden 500 miles also and cannot be sure if the plugs carbon deposits have been caused by rather the too rich carb. or oil or both!

In any case the apparent too rich case needs to be cared for but after two years now of looking into it (believe me that I have read and tried all edelbrock's pamphlets,etc.) I am just wondering if the carb has not some defects that avoid all tuning efforts!?

thanks,Ronald.
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Old 10-27-2005, 07:35 AM
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In some applications having too small of a carb will cause it to run rich as the smaller venturies will create higher velocity and hence draw more fuel from the carb. Going to a 750 cfm of whatever brand may help somewhat.
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Old 10-27-2005, 07:51 AM
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Quote:
Originally Posted by Steve karch
In some applications having too small of a carb will cause it to run rich as the smaller venturies will create higher velocity and hence draw more fuel from the carb. Going to a 750 cfm of whatever brand may help somewhat.
Steve,

Your comment makes a lot of sense...among all theorical possibilities that came through my mind that exactly one pictured itself in my brain and still does..the problem is how could I check the validity of the theory without having to deal with actually buying,trying a bunch of different brand,size of carbs..an exercise that could just drive me crazier than whatever I am after two years of fiddling with the problem already!
thanks.Ronald
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Old 10-27-2005, 08:41 AM
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Ask around..

I agree your carb might be a bit small. When I ran into a similar problem I borrowed a carb from a friend to check my theory. Ask around at your local hotrod club somebody should have one on a shelf that they might lend you or make you a good deal on.. Try www.craigslist.com in your area.
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Old 10-27-2005, 09:23 AM
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Quote:
Originally Posted by TVR383
Steve,

Your comment makes a lot of sense...among all theorical possibilities that came through my mind that exactly one pictured itself in my brain and still does..the problem is how could I check the validity of the theory without having to deal with actually buying,trying a bunch of different brand,size of carbs..an exercise that could just drive me crazier than whatever I am after two years of fiddling with the problem already!
thanks.Ronald
Small carbs don't do this. All they will do is create a better booster signal.

A 230@.050 cam is not to big for a Edie carb

Black and hard deposits are an oil control problem not a carb problem. Bad plugs,(fouled out, not hot enough) will cause similar issue's.
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Old 10-27-2005, 09:46 AM
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are the primaries opened to far in order to maintain idle speed with the lumpy cam?on a holley doing this causes the engine to begin pulling from the main metering ciruit causing rich mixtures. Afix for holley is to drill.125 holes in each primary throttle plate.allowing the plates to be closed back to allow the proper amount of idle slot exposure.
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Old 10-27-2005, 10:14 AM
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agree with johnsongrass....

if you are showing 15+Hg at idle (700rpm?) with the 230 cam then start looking elsewhere......weak spark, cold plugs, timing, cap and rotor, etc.

only 500 miles since the re-build!!! drive it about 2000 miles checking for oil loss......easily can be the rings not seated yet
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Old 10-27-2005, 12:55 PM
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Quote:
Originally Posted by johnsongrass1
Small carbs don't do this. All they will do is create a better booster signal.

A 230@.050 cam is not to big for a Edie carb

Black and hard deposits are an oil control problem not a carb problem. Bad plugs,(fouled out, not hot enough) will cause similar issue's.
I need to make a correction about my cam it is a 220 int. 231 exhst at .050. Plugs are now carbon fouled after 500 miles but were brand new 12Y champion to begin with..can and should I get hotter ones?

About the idle circuit adjustement if I close the screws further in it just won't keep idling good specially when cold where they are now doesn't get gaz sucked in from main circuit..it did but I backed them off.


About the primary plates getting drilled .125 holes..that is what I was thinking first ..my understanding is that would have effect only in closed to almost closed in primary throttle plates allowing extra air but while cruising,partially opened plates at angle what kind of extra air would this allow?

thanks,for the inputs,
Ronald.
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Old 10-27-2005, 01:48 PM
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Ronald
What is your initial timing and where do you have your vacuum advance hooked into. Is it ported or manifold vacuum
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Old 10-27-2005, 01:50 PM
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Quote:
Originally Posted by TVR383
I need to make a correction about my cam it is a 220 int. 231 exhst at .050. Plugs are now carbon fouled after 500 miles but were brand new 12Y champion to begin with..can and should I get hotter ones?

About the idle circuit adjustement if I close the screws further in it just won't keep idling good specially when cold where they are now doesn't get gaz sucked in from main circuit..it did but I backed them off.


About the primary plates getting drilled .125 holes..that is what I was thinking first ..my understanding is that would have effect only in closed to almost closed in primary throttle plates allowing extra air but while cruising, partially opened plates at angle what kind of extra air would this allow?

thanks,for the inputs,
Ronald.
Hard stuff is oil. Soft stuff is fuel. A hotter plug might help but with sucjh few miles you can't say anything yet. The idle mixture screws don't pull from the main circiut ever. You won't pull from the main till around half throttle or a little less. You can't set up a carb to run cold and hot without a choke. Too many compromises are present. When ever doing adjustment's you should drive till full operating temps have been established. This usaully takes about 5 miles or so of constant same speed driving. You don't even haveenough miles on her to worry yet. Get another 1500 or so and make adjustment's to fine tune then. It's quite common to foul a plug while seating the rings. Just clean 'em and go till you get about 2000 miles. Then fine tune. You may even find you have to tinker a little after 5000 miles when things have worn off the new.
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Old 10-27-2005, 03:53 PM
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Quote:
Originally Posted by Steve karch
Ronald
What is your initial timing and where do you have your vacuum advance hooked into. Is it ported or manifold vacuum
,,

Steve,
I've put the initial timing at 17/700-800 difficult to be precise as it varies the idle somewhat cause of the cam I guess (among other uncontrolables!). I'm not sure I get right your second question but its a mechanical advance MSD so no vacuum advance here..I get my vacuum readings from a hook up to the carb...
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