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Edelbrock 600 CFM (#1406) to replace stock 79 L-48 Quadrajet?

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Old 02-28-2012, 02:54 PM   #1
Neo Fender
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Member Since: Mar 2001
Location: St. Louis, Missouri
Default Edelbrock 600 CFM (#1406) to replace stock 79 L-48 Quadrajet?

My original Carter (yes Carter) Quadrajet still causes the idle to be a little high. It may be the ubiquitous butterfly shaft leak (bushings). I have an Edelbrock 600 CFM carburetor. Will it fit and be worth the effort or should I fix the Q-jet?

* Original manifold
* Quadrajet-spread bore (IIRC), Edelbrock-square bore (bolt pattern?)
* Throttle linkage?
* Automatic transmission kickdown?
* PCV, EGR, Power brake booster, vacuum advance, etc.?

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Old 02-28-2012, 03:00 PM   #2
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Member Since: May 2006
Location: Danbury CT

Fix the Quad. Squirt some carb cleaner on shaft and see if idle changes to confirm your thought.
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Old 02-28-2012, 04:36 PM   #3
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Member Since: Jan 2006
Location: Crossville TN

Unless someone has drilled holes in the primary throttle plates of your Q-Jet, there is no reason that you can't get the idle to adjust where you need it, unless the linkage is sticky or the carb is not adjusted properly. I have known of carbs that are not placed 'centrally' on the intake, causing the throttle plates not to close completely. That's fixed by loosening the 4 attaching bolts and wiggling the carb into a more central position, then retightening to specifice torque.

I would tend to agree that rebuilding/adjusting your original Q-Jet is likely the best way to go. And it certainly will be the least expensive of your choices. Before you reinstall it, make all carb and choke adjustments per the Chevrolet Chassis Service Manual for your year car.
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Old 02-28-2012, 07:53 PM   #4
Oldguard 7
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Location: Norfolk VA

I agree with the others. Get the q jet rebuilt. I bought the. Edel 1406 carb and like a dummy I gave away my qjet to my instructor while in auto tech school. I should have known something was up when his face lit up as I handed it to him. As for the 1406 carb, I bought the edel 2101 manifold so I wouldnt have to buy an carb adapter plate. I have not have had problems with it as it still sits atop my engine. But is is not a performance carb. If I can stop being lazy, I will replace that manifold/carb combo with a Stealth manifold and a 750 mighty demon carb (both new in box a few years ago)
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Old 02-29-2012, 06:53 AM   #5
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I agree with others that fixing the OEM Qjet would be the best bet. I replaced my Qjet with a Holley 4175 650 Spreadbore replacement in 1985 and it has been perfect (just rebuild it myself about 1 year ago and running great again) but like oldguard7 let a buddy of mine "borrow" my OEM Qjet to run on his built Pontiac 400 in an 80 Trans AM in the 80's, engine backfired through the carb catching the carb on fire (I was not there at the time) destroying the carb-I am still pissed at him for that blunder! Never saw my OEM Qjet again-Knowing what I know now, I sure wish I still had it and would have at least tried to get it in running perfectly, even if I didn't use it on the car.

Last edited by jb78L-82; 02-29-2012 at 06:57 AM.
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Old 02-29-2012, 06:53 AM
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