Edelbrock Carb idle issues

[Huck]

Over the years I have always seemed to have issues with the Edelbrock 1405 and 1406 carbs running too rich at idle. I've tried to adjust the mix screws, jets, etc. and no matter what I've tried, idle would load up over time. Now I'm not talking about one or two trucks or one or two carbs but maybe a dozen. Meet a couple of the Edelbrock factory reps today at the Pumpkin Run swap meet in Ohio. Both agreeded that the most probably and common cause is that the stock fuel pumps tend to put out between 5 and 9 lbs of fuel pressure which is too high for the Edelbrock carbs. They explained that their carb is really a redesign of the Carter Carb but that their design cannot handle more then 5 lbs of fuel pressure. They recommend putting a fuel pressure gauge and adjust fuel pressure to around 4.5 lbs which would probably require a fuel regulator. I will try to work that into my schedule in the next few days and let you all know the result. Huck

[mtdave2]

you know i have the same issue with it being a bit rich. i see a black puff a smoke more often than a want to. choke is all the way open.. so i guess this could make sence....

is there an easy fix?

[piecesparts]

Originally Posted by Huck

Over the years I have always seemed to have issues with the Edelbrock 1405 and 1406 carbs running too rich at idle. I've tried to adjust the mix screws, jets, etc. and no matter what I've tried, idle would load up over time. Now I'm not talking about one or two trucks or one or two carbs but maybe a dozen. Meet a couple of the Edelbrock factory reps today at the Pumpkin Run swap meet in Ohio. Both agreeded that the most probably and common cause is that the stock fuel pumps tend to put out between 5 and 9 lbs of fuel pressure which is too high for the Edelbrock carbs. They explained that their carb is really a redesign of the Carter Carb but that their design cannot handle more then 5 lbs of fuel pressure. They recommend putting a fuel pressure gauge and adjust fuel pressure to around 4.5 lbs which would probably require a fuel regulator. I will try to work that into my schedule in the next few days and let you all know the result. Huck

I haaaave run several Edelbrock carbs (1406) and also the Carter carb equivalent. The guys from Edelbrock are smoking dope---the two carbs are the exact same model of carb from an OUTSIDE supplier. If you look closely the body of the carb will have a "Weber" name stamped on it. That is because both companies buy the carb, parts from a company called Magneti-Mareli and sell them under their name. The parts for the Edelbrock is cheaper than the ones for the Carter, but they are the exact same items and fit both bodies (been there and done it). My Carter is essentially filled with Edelbrock carb parts.

As for the running rich--both carbs (Edelbrock and Carter) have the exact same floats and needles in them, so they both should load up if the fuel pressure is too high. I do not have a pressure regulator on my AVS carb and did not have one on the Carter before it and I have not had a loading issue on my truck or my son's truck (1406 carb). I set my idle mixtures using a vacuum gauge for the best idle condition and vacuum signal when idling---this works quite well for getting the optimim out of a carb. I also have my idles set at 700 to 800 RPM in DRIVE. The timing on our trucks is set at 35 degrees TOTAL, which moves the initial timing quite a ways up on the BTDC tag. My truck is a 385 stroker motor and my son's truck is a 350 with a different cam profile. I used to run a factory fuel pump on my truck, but now have an Edelbrock street pump and my son still has his stock fuel pump.

I have also changed out my needles and jets to get the performance where I want it, but that had nothing to do with the idle circuit--the tuning was for the transition point and the WOT performance.

[uncle]

Last one I ran,I had decent luck by lowering the float level.

[byrd]

I had the same problem with my 1406 and used a reg to rectify it and it worked OK. When I did a little under hood clean up of my driver I took to Street and strip here locally and they rejetted and set up the carb and timing and I picked up at least 25 HP and it runs better than it ever has before, but this time, no reg required, still have the stock pump and the carb doesn't load up at all Wierd?? They charge $65 plus the cost of new NGK plugs for what they call a performance tune(may require more than one attempt, same visit just another go around, and each one costs $65) Just a thought if you want to go this route....

[gator2511]

I can only tell you that I had what appears to be the same symptom. I put a fuel pressure regulator on it and the problem went away immediately.

[mtdave2]

so is there a generic one that you got?

[gator2511]

Originally Posted by mtdave2

so is there a generic one that you got?

I bought a Holley off Sumitt. I also put a pressure gauge in one end of it so I can tell what I'm doing when I adjust it.

[wHATANERD]

I've got the 1406 on my truck aswell and also get a rich idle. When I complete my engine swap I'm planning on going with the Edelbrock Performer Fuel Pump which doesn't require a regulator.

[soba_03]

Just finished my engine r/r, Edlebrock 1405 as well, Until got out the tach and vacuum gage it was rich as well. But once tuned it's a happy camper.... stock fuel pump not regulator.....

[wedgemon]

I know about the "Best Idle" tuning from the Edelbrock Manual. How do you tune with the vacuum gauge???

- Dave

[soba_03]

Well I was told that set carb up to idle where you want it and then check vacuum to obtain the best vacuum. This will turn out to be the best spot for the carb. I have no idea if it's right. However it does create a very nice light brown plug. So I'm sticking with it. Even though your idle is set within that idle setting you can set vacuum too with the idle screw. It's the right idle speed with the most vacuum.

[70rs/ss]

In my case I live at 5500-6000 ft/elev so I need to rejet mine, but the edels don't like anything over 5-6 psi so put a guage on it first and if you're over that a regulator will fix it, as for tuning you may need to do a jet or rod change to get it where it needs to be, but other than that, they are dead on reliable.

[piecesparts]

Setting the idle with a vacuum gauge:

Connect the gauge to a vacuum port on your intake manifold (it is better to not use one off of the carb base--better signal response from the manifold). With the engine running at what you would like for an idle speed ( I chose about 800 RPMs for mine) adjust one of the idle/air mix screws inward until you get a drop in idle speed. Next turn that screw outward watching the vacuum gauge for an increase in vacuum signal. When that signal stops increasing stop there. Now, do the other idle/air mix screw the same way and watch the vacuum signal for an increase. NOTE: You may have to adjust your idle speed on the carb to keep it where you want it.

NOW: Do the same process once again with each of the screws until you are sure that you have the best adjustment capable.

FINALLY: The last thing you want to do is turn both of the idle/air mix screws inward an 1/8th of a turn. You are done with setting the mixture on your idle settings.


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