How'd you get the mixture right? I'm going by what the book sez, warmed up, air cleaner on, etc, but the IMS screws are all the way IN, like seated, and the thing is still wayyyyyyy rich. It's in the garage and making my eyes burn! How do I lean it out? The idle speed is 900 RPM, everything else is good. BTW, if it matters, it's on a 360 Mopar. Thanks...cough cough cough... Jay
Probably got some sort of leak internally...if it was a Holley, I'd suspect a power valve, but I'm not too sure on Edelbrocks. But, I doubt that carb size has anything to do with it...I just put an 800cfm Edelbrock on my truck yesterday, and it burns perfect. If you got the mixture screws all the way in and it's still way rich at an idel, you have a stuck float, a float set too high, or some other problem causing fuel to get into the venturis when it shouldn't be.
Are you running a big cam? Even a medium size cam can screw things up for you when trying to set the idle mix on an edelbrock carb. It is a vac secondary carb , and if it is not seeing enough vac at idle, the secondaries will "fall open a little". Are you having a hard time getting a real consistant idle speed, like once you get it set, blip the throttle a couple of times and then the idle speed it higher or lower? That would be another symptom of the carb not being happy with the vacuum at idle. Set it as best as you can, and then take the air cleaner off and with it running at idle use a flash light and look down into the throttle bores. You will see fuel spilling into the throttle bores if this is your problem. A little different spring should cure the problem. Edelbrock has a set very good tuning instructions on there web site. - Duane
I bought a couple of the small ones for some mid 80's dump trucks at work. I just didn't have the time to get the ancient Holley's working right [Smogger, vacuum secondary 4 barrels with Governors on 'em 4160 series] and in the interest of saving time, I scored the Edelbrocks with hand chokes. They went on bone stock 370 cu in ford V/8s....destroked 429's with a small bore. I had the same problem! They weren't as rich running as the junk Holleys but they still foul plugs. Naturally, I didn't have any time to dedicate to setting float levels or buying an asortment of jets.....everything there is a panic. The main selling point was immediate satisfaction and I don't feel they delivered. Hell, I didn't care if the damn carb was chrome plated. I just wanted a carb I could bolt on and set the idle mixture and Idle speed before the truck hadda be driven out from under the conveyor belt it sits under....fills up every 3 hours with stuff I don't wanna talk about.......stuff that doesn't chemically break down after flushing it down the shitter.......know whatta mean? Gag me with a tampon! Signed: Unsatisfied.
Had a 600 Edelbrock on my old 283 plus .060 too big......... Bought a new 500 Edelbrock....better ...but still had to play with the step up springs and changed the metering rods 1 size smaller........worked good.....BUT I have a Holley on the 32 roadster and have another new Holley for the 32 3W.....when it gets going..... .
If the screws are seated I would suspect that you have some trash in the needles or the floats are stuck. I would also put a straight edge on the base make sure it is not leaking at the base. Sometime they are just worn internally. I hope this helps Slick Willie
If you kick the idle screw up to 900 rpm you are no longer in the idle circuit, it's trying to idle on the mid range system and it won't ever like it. Open the mixture screws back up to where they were when you took it out of the box, or if you don't know try 2 1/2 turns each then start it and turn the idle speed screw out/down to 650 rpm. then adjust the mixture screws. If you can still close them and it keeps running you've got a vacuum leak somewhere.
Thank God... I have an Edelbrock with some of the same problems, but I have no manuals or anything on it. Maybe I will try some of these suggestions tommorrow. That;s what I get from buyin' an engine already built huh?
I just had this problem a week ago. In my case, I left out the plug in the back of the carb, 1/4" pipe, used for the power brake booster. Makes a big vacuum leak. Dr. J is right, at 900 rpm, you are out of the idle circuit. I had a deal a few years ago, with a local speed shop, all the Edelbrock carbs that were returned, he sold to me at cost, saved him the hassle on warrantee, and I got cheap carbs. Over a couple years, I got about a dozen of them. Outside of normal adjustments, I never had to do anything to them to make them work. None of them ever came back with problems. Double check everything.
All the manuals and tuning guides are available free on Edelbrock's site They're also notorious for needing the floats set from the git-go..
Damn, Rocky...my experience went totally the other way! When I bought my truck, it had some 80s reject feedback QUADRAJET rigged up on the 460 (really big 370!) engine! The dope I bought it from had nothing hooked to the electrical plugs on the Quadrajunk, of course, and to say it ran like shit would be the understatement of the decade! So, I bought a used Holley 780 from a swap meet shiester, and gave it a rebuild. Still leaked like a bitch and the base was warped! Having owned one other Edelbrock years ago, and finding it to be 'good enough for a driver', I went to the local speed shop a couple days ago and bought a brand new Edelbrock EPS 800cfm carb. I dropped it on 'out of the box' and the truck fired up easily and runs incredible! I haven't even bothered to set the mixture or speed screws yet...it idles at about 700rpm and the throttle response is uncanny! Tried easing out of the parking lot at our local cruisin' spot last night and STILL left a few feet of rubber on the ground! I got the choke wired open, and when cold it just takes one pump to start it, followed with a little feathering of the gas pedal for a minute or two to get it to idle. Hot starts were a total bitch with the old carb, now all you do is bump the key and it lights right off and idles perfectly. (Even with the 800 carb's bigger accelerator pump and raised booster, it doesn't run rich at all...I considered buying a 600 or 750cfm Edelbrock, but figured I'd "go big" and get the 800 for a few bucks more. I'm so impressed with it that I doubt I'll ever fuck with a Holley again!)
I bought a new intake and 600 man choke for my 307 68 chevy pickemup. Right out of the box seemed to work great. even in the dead of winter w/o the choke hooked up, just a little feathering and she's good to go. I'm pretty happy with how it performs. my 2 centavos phil
Running a big cam? If so, the lower manifold vacuum levels are pulling the rods up at idle and low speed. Vacuum keeps the rods down (lean) and springs raise em up (richer). Get a spring kit from Summit or Jegs or the local shop that carries that stuff. (Price about $5. - $7. depending....) The pink spring may be about right, but it's best to note the springs vacuum rating and stick a vacuum gauge on your engine to see precisely what the engine wants. Go too far in the weaker spring dept and you'll end up with a flat spot when the secondaries come in.
Aha. Thanks for all the idears. It worked fine outta the box, but after sitting over the winter it's running uber rich. I didn't think about the float deal, but even after tapping it with a hammer last night it didn't help. The idle is actually about 750, I just have a CRAPPY factory stock Chrysler tachometer. It reads erraticly and I was typing quick and not thinking of what I was saying. Oh well, back out to try again. Someone came over with BEER last night and I got, um, sidetracked. Thanks again everyone. Oh btw, I don't consider the cam large (.450/.455 268 adv. dur, I think) but is that what could be doing it? No vacuum leaks, at least around the carb. Tried the brake clean test for that... Jay
i have a 270 adv. duration with .500 lift with an edlebrock 500 on my 289. maybe something dried out internally or something, and like you said it sat during the winter...maybe something is caught in the carb...just some gunk. snake9t9...these carb have mechanical secondaries right? you said that if the carb doesn't see enough vacuum the secondaries will fall open a little...am i missing something?
Well, sorta, I screwed up when I said "secondaries" what I mean is that while the butterflies are opened mechanically, the fuel enrichment circuits are operating based on vacuum. And what is actually opening first is the "primary enrichmnet" ciruit because the step up springs allow the metering rod to open the passage at the jet. This will happen in a low vac situation. If this is happening at idle you will be able to see the un atomized fuel pouring down the throttle bore, and to correct the problem you would need to use a differnt step-up spring.
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