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 Edelbrock 1403 one side rich 
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Joined: Sat Feb 25, 2017 11:58 am
Posts: 9
Edelbrock 1403 (500 cfm) still sporting what appears to be factory calibration. Showed up here on a Torker single plane intake on a mild (stock?) Ford 289, with complaints of weak power, stumbles off the line, poor fuel economy, and short plug life. The carb appeared to have been run very little, no debris inside, blasted passages with some carb cleaner and it looked new. Plugs were 100% soot covered, initial timing 4* total 24* @2500.

Dumped the Torker for a dual plane (Jegs Performer copy), set the floats and transfer slot, set idle mixture to 1.5 turns, set initial to 12*. Cleaned up the plugs a bit and reinstalled them. Starts right up, burbles nicely at 700 rpm, 16.5", in gear pulls down to 600ish and 14". Drives better, especially off-idle, but still feels blubbery at moderate load.

Looking at the plugs tells me that the drivers side is running pig rich, the passenger side can use a bit of tuning but it isn't way off. Rods, springs and jets are the same for both sides, does anybody have any detail pics I can look at to see if everything is drilled / tubed correctly? This sounds like what Tuner mentioned here: http://racingfuelsystems.myfunforum.org/viewtopic.php?f=30&t=1193, how do I adjust the tube to uncover the bleed, or might something else be at play?


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Thu Jun 15, 2017 8:43 pm
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Joined: Mon May 15, 2017 4:04 pm
Posts: 80
I would start with a new set of plugs and go from there. If it is a low compression engine I would bump the timing a few more degree's and see how it does.


Thu Jun 15, 2017 10:49 pm
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Joined: Fri Feb 08, 2013 2:37 pm
Posts: 1744
You need to check the size of the idle jets. They are the pinch at the bottom end of the small tube hanging from the booster. It is common to find these carbs with two different size idle jets.

Another problem common to these carbs is the idle air bleed on top of the cluster is bashed partly closed, sometimes substantially so. It looks to me as if the machine tooling which inserts the main air bleed tube (brass tube pinched at the top pressed into top of cluster) tried to push it into the wrong hole.

Sometimes, the main air bleed tube orifices are different size.

Sometimes one (or both) primary emulsion tube gets pressed into the booster casting a little too far and the 'kill bleed' is blocked or partly blocked. In these carbs the kill bleed is drilled in the aluminum casting at an upward angle just above the inserted brass emulsion tube. The KB is probably .029" or .031", the smaller is preferred, but they both should be the same size.

Naturally, the float level and needle and seat size must be identical on each side.


Fri Jun 16, 2017 2:22 am
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Joined: Sat Feb 25, 2017 11:58 am
Posts: 9
Thanks for the tips. I'll pin them out to see what is what. Any idea what the correct idle jet size is? Can the emulsion tube be wiggled back out a bit to get clearance, or will I need to replace the tube?

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Fri Jun 16, 2017 2:49 pm
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The size of the idle jet depends on the other orifices in the idle circuit, 1st IAB (on top of cluster) and the Economizer (in the cluster) behind the 2nd IAB (on the side of the cluster), usually between .031" and .035".

The E-Tube, you could pull it down some. Run it under hot tap water or wear some heavy pigskin gloves and heat the cluster with a butane torch and use an old drill bit that fits the large E-holes as a wrench to twist it and pull. I use 3/16" brass tube to make E-tubes to mimic the old OE carbs on 340 HP 327 Chevy or 375 HP 440 Mopar. Zoom in on the picture in this thread viewtopic.php?f=28&t=22&p=30&hilit=cluster#p30 to see some OE tubes. I like to use .026" E-holes, 3 or 4 to a tube. Almost anything works better than the tubes with the large holes near the bottom, they blob and slug the fuel in clots at the beginning of flow. Just a straight tube with a couple/three .026" holes makes a smooth flow. Kill bleed in the aluminum casting above the tube is usually .029"~.031", the smaller preferred.

If the secondary booster has the .073" hole in the bottom end it will undoubtedly not be rich enough at WOT, no matter the jet size ....... you need to open that to the full ID of the tube.


Thu Jun 22, 2017 2:45 am
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