Here's one for the edelbrock-big block guys

"Kermit" has gone from running like a swiss watch to loading up on fuel at an idle . Found one side a little different from the other somehow , adjusted them even, seemed a little better but still loading up at idle . Cruising speed to w.o.t. is crisp as always , what could have changed ? The block is stock , unported D3 heads , edelbrock performer intake ,edelbrock 600 performer carb , mild cam , crites long tubes , 2.5" exhaust , pertronix flame thrower 2 dizzy + coil . The P.O. told me it was a 750 carb , after looking up the model no , it's a 600 . Is that enough for this set up ? If so , where do you suppose my gremlin is in it ?

"Kermit" has gone from running like a swiss watch to loading up on fuel at an idle . Found one side a little different from the other somehow , adjusted them even, seemed a little better but still loading up at idle . Cruising speed to w.o.t. is crisp as always , what could have changed ? The block is stock , unported D3 heads , edelbrock performer intake ,edelbrock 600 performer carb , mild cam , crites long tubes , 2.5" exhaust , pertronix flame thrower 2 dizzy + coil . The P.O. told me it was a 750 carb , after looking up the model no , it's a 600 . Is that enough for this set up ? If so , where do you suppose my gremlin is in it ?

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Your saying it ran perfect before..It's loading up at idle..so I would say Idle circuit of the carb..If it sat for a bit without being run & no ethanol protector additive in the fuel..I'd start with the carb ..cleaning rebuild..new pre carb fuel filter too..It has to be something simple like some dirt.. buildup in one of the needle valves, seats, passages

+1 on Q's statement, it is the idle circuit being contaminated. Take one mixture volume screw out, spray a little carb cleaner in the hole with the provided tube. Put the screw back in and do the same thing on the other mixture volume screw. If that don't fix it, you might try doing the same thing folioed by compressed air. Also, 600 cfm is not enough for a 460 with a mild cam. If you decide to change carbs, consider a Holley or the summit brand in the 750ish range. Perhaps even more depending on a lot of things with the current set up and future plans. Let us know how things develop. Chuck

EDIT: The idle volume screws should end up between 1 and 2 turns out.

Thanks guys , I"ll try that . I thought a 600 was a little small too , but it ran real nice before this . If I can't get it smoothed out , I"ll spring for that 750 before I go nuts with the 600 .

The smaller carb will only limit your ultimate power potential, daily driving with a smaller carb won't hurt anything, it should actually be more responsive.

Sounds like some trash or moisture is caught in the carb's idle circuit somewhere. Blended fuels contain more alcohol which absorbs moisture and eats fuel lines that are the older, non-alky resistant type...

Dig out the book on the Edelbrock Performer carbs. Mine was running mega-rich at the traditional 1.5-2-ish turns out. From what I read, the mixture screws do the opposite of traditional thinking (rich vs. lean). I've always been of the impression that turning the idle mix screws clockwise, would richen the mix (closing off the idle air bleed), but that's not the case - clockwise to lean, counter-clockwise to richen.

http://www.edelbrock.com/automotive/misc/tech-center/dl/carb-owners-manual.pdf

I "fiddled" with mine for awhile (thinking I knew what was what), and noticed it was running rich, and kept getting richer... then stumbled a bit when 'brapping' the throttle. Then the first Duraspark module smoked after I rewired it as CZ-75 did his. When the second module smoked, and I rewired it back to how I had originally wired it, I decided to actually use the book to adjust my carb. BIG difference - no rich, no stumbling, and even more throttle response.

Cleaning never hurts. Scott's and Chuck's advice is spot-on as always. I just wanted to share what I found [and was wrong about] when adjusting mine.

Well , I tried taking out the mixture screws and spraying some carb cleaner , no better . Then tried a little compressed air , thought it was better but after a couple minutes of idling it died . I played with the screws between 1-2 turns no better . The P.O. had them set @ 3 1/2 turns for some reason , but it ran great for the 2 yrs I"ve owned it . I'm not thinking ignition , because last year I put in a brand new pertronix billet dizzy and coil to cure a glitch in the pro comp P.O.S. dizzy that was on it . So , do I buy the $50 rebuild kit and hope I don't need to also buy the floats and accel pump or suck it up and get a 750 cfm . Seems funny it ran so good for 2 yrs on the 600 , but am I leaving horses on the table by not using a 750 ?

It hasn't sucked up rust or crap from the tank ? Do you have an inline filter you can check? Does it run under part throttle or stall out after a little while.

It hasn't sucked up rust or crap from the tank ? Do you have an inline filter you can check? Does it run under part throttle or stall out after a little while.

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It has a clear see-through filter that looks great , carb and fuel lines less than 4 yrs old . It runs great above idle to w.o.t. , but stalls out after a few mins. of idle , stumbles bad , then only will re-start if you floor it when cranking . Been driving at least once a week so it hasn't been sitting .

Well , I tried taking out the mixture screws and spraying some carb cleaner , no better . Then tried a little compressed air , thought it was better but after a couple minutes of idling it died . I played with the screws between 1-2 turns no better . The P.O. had them set @ 3 1/2 turns for some reason , but it ran great for the 2 yrs I"ve owned it . I'm not thinking ignition , because last year I put in a brand new pertronix billet dizzy and coil to cure a glitch in the pro comp P.O.S. dizzy that was on it . So , do I buy the $50 rebuild kit and hope I don't need to also buy the floats and accel pump or suck it up and get a 750 cfm . Seems funny it ran so good for 2 yrs on the 600 , but am I leaving horses on the table by not using a 750 ?

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It's 100% a carb problem..Since blowing air carb cleaner didn't work But did seem better for a bit..You have a piece something in there OR the needle valve tips could be worn Or the seats o-rings could be worn..gaskets..I've seen where gaskets degrade over time a small piece lodges inside..As I said I would do a full rebuild gaskets seats needle valves o-rings etc. Or just drop the bucks on a new carb If it ran good on a 600 then I would do the holley street avenger 670 no need to go to a 750 if you were happy with the 600 reasonable price great carb under $400..Just thinking you did check the float height..nuts adjustment while on level ground right ? Sometimes they can loosen up Opps Holley on the brain I think you have to remove the top plate on a Eddy to adjust the float but It's still some thing I would check

Does sound like there is some bit of crap in there to me but Hey I don't know too much ? More mechanical guys will give you the best repair tips.

I had an edelbrock 600 that suddenly developed idle problems and the culprit was in the idle circuit as previously mentioned. Looking at the top of the carb notice the 2 small tubes sticking straight out of the top of it on the left and right. Try spraying carb cleaner and/or compessed air down in the them to clear them out , if that doesn't work you will have to remove the top of the carb to get to the idle mixture boosters that will be romoved by loosening the 2 torx screws holding each on one. Mine was clogged by a piece of brass flashing clogging the tube at the bottom of the assembly. Cleared it out, put it back together and it idled like new again.

fuel psi was a culprit for me, dont know what edel carbs max psi spec is but if its too high it will start flooding when it gets up to temp. a bad pcv valve has stumped me before with similar symptoms.

After spraying carb cleaner behind the idle mixture screws , a little compressed air and a few curses it finally passed whatever was bothering it and is galloping smoothly again . :banana: Thanks for the replies .

I'm glad you got it going again. Just look at it as the automotive version of sea food that is not quite right. Chuck