First off, yes, I'm aware of the search feature. The general consensus seems to be that Edelbrocks carbs seem to have loose screws and the floats are to high. So of course that's the first thing we tried... Now, on with the back story. The carb is an Edelbrock 1406 (electric choke) 600 cfm unit. It's bolted to an Edelbrock performer intake that sits atop a 350 engine that is stock aside from 1.52 roller tip rockers and a Competion Cams 268 camshaft. The car runs like mad going down the road but wants to load up if I try to let it idle for long periods of time while in gear (sitting in traffic). When it first starts I can usually bump it into neutral and clear it out. If I'm unable to get moving it will eventually start loading up so bad that it dies on me. Sometimes it'll crank right back up and sometimes it wont. The warmer the weather is outside the worse it seems to do it. I can crank the car while it's cold and it seems that it will idle indefinitly without loading up and my temp gauge stays right at 160*. If I jump in and tear down the road at a high rate of speed and manage to get the temp closer to 180*, once I stop, the car will idle for a few minutes and then start to load up. We've adjusted the choke, idled the car up and adjusted the air/fuel mixture screws. Everything seems to have helped (or we could just be imagining it and are just a bunch of wishful thinkers) but the problem still isn't fixed. Now, we'll just throw a couple other symptoms in here for good measure. The fuel in the clear filter (no it's not glass) pretty much fills the filter when I first crank the car. Once the car has ran for a while the level might be full, half full or look nearly empty. This could all be normal as I'm not a wealth of information when it comes to things like this. Also when the car gets up to temp it seems like the fuel in the filter looks rather...Agitated, for a lack of a better description. It's been suggested that my fuel is getting overheated and that I should reroute the line. It's presently not ran that much differently then the other four V8s in my yard but who knows? It's also been suggested that if I placed a spacer inbetween the intake and the carburetor my problem might be alleviated. I've got no experience with carburetor spacers so I'm clueless here as well. So...in closing, does anyone have any suggestions on how to get this car to idle in the heat without shutting down? Thanks in advance for any assistance guys!
Two things I think. Get a pressure regulator on the system and crank the pressure down to 4 1/2 - 5#. Holley makes an excellent dead-head style that isn't too expensive. Get a metering rod spring kit and install some softer springs - probably pink. Along with this, go here: http://www.edelbrock.com/automotive_new/misc/tech_center/install/1000/1406_manual.pdf And read the section on metering rods. Basically, the springs open the metering rods and vacuum shuts them. With an about 270* advertised duration cam the engine has low vacuum at idle, probably 11-14" and it is allowing the stronger "as-supplied" factory spring to pull the metering rods open too early which is allowing excess fuel in at idle and low speeds. If you swap springs, be sure and put them in a well-marked container. Pill bottles and baggies marked with a Sharpie work well. What happens here is the fuel washes the paint color off the springs and you can't tell what they are. Lastly, get yourself a vacuum gauge and fuel pressure gauge. Toolbox or better yet on the car. Be sure and run a fuel pressure isolater so you don't get gasoline inside the car if there's a leak.
Has it done it since you put the carb on.. or did it start after the the carb had been on there running ok. 600 sounds like the perfect size for that combo. Was it a new carb or do you know the history of it before you put it on? Could be metering rod or squirter size had been changed if it was possibly ran on another motor.
I dont know if this is a factor in your problem or not, but when I read 350 c.i.d., I thought "650cfm". I know it's not an exact art through a monitor, but try this link. I ran a 600 Edelborck on a 531C, and it sucked. Slammed on a 650, good to go. Here's a link to a good calculator, that the Land Speed Guys let me in on. Just my $0.02. http://www.csgnetwork.com/automotiveconverters.html
I would 'start' at the metering rods. Look at the schematic that was posted, shoot for maybe too lean. If nothing else, pull the needles and seats and see what size they are and compare them to the chart. Then buy whatever needles and seats you need till you get to the ballpark. Keep a little notebook or something so you know where you are with the combination and know what you need to change; sometimes a needle set, sometimes both. Ideally, keep going lean until you start seeing some lean burn issues, then move back where you came until it stops. Ideally, for a ball park idle richness test, I would partially cover the carb with my hand at idle and hot. If the rpm would pick up just a bit before falling off or dying, I would think I am just about right. That would suggest that it is running a little lean, and covering the intake would richen the mixture. If it died right away, it was already rich enough or more than ideal. Really a simple trick, and not something for high perf tuning, but for a driveway test, it seems to work on regular driver motors.
Thanks for the great feedback so far guys! The carb was purchased as a remanufactured unit (reman by Edelbrock I assume...got it at Oreilly's) and put on a newly rebuilt engine we had put together for my wifes 54 Chevy 210. We first got the car running last fall when the weather was cool outside. It ran like a champ all winter. Issues didn't start to arise until the weather warmed up this spring. The hotter it gets outside, the faster she wants to load up at idle. We had an unusually cool weekend about a month ago (mid 70s) and she ran like a champ that day. When the loading up symptoms first appeared, the car also seemed to develop a "bog" or hesitation when acclerating from a stop (didn't matter if the car was cold or warm). Apparently one of, or a combination of the adjustments we've made since then seems to have corrected the "bogging down"...but not the loading up. Thanks again guys!
Same exact combo I have, carb, cam, engine, runs fine if fuel pressure limited to values per Edelbrock tech sheet. Also running a 1" carb spacer insulator under mine
First off I want to say that was a very detailed and well written post. Next I'd say listen to C9 and get a fuel pressure gauge on there. I suspect you may have a mechanical pump with marginally high pressure that is fine at idle when you first start it, but as you bring the RPM's up the pressure spikes and overloads the needle and seat, flooding the engine. It would also take a little while to bleed down, which makes sense with the symptoms you described. If so, the boosters should be dribbling when this happens, probably even after you shut the engine off.
One I still run did have the float set way too high, even though it was set to Edelbrock specs. I had to set it using OLD specs for something like a big muscle Pontiac with AFB that I found the specs in Motors Manual. Mine would flood & die with little chance of restart if I pulled off the shoulder on angled banking. This one still starts real hard on a heat soak restart, and must be boiling over and flooding. Another on a used truck had one float that had gas in it. They solder the 2 halves of each float together, then solder a vent hole last. The vent hole solder had a pinhole that somehow corrored itself shut again AFTER it allowed "some" gas inside. I even heated it lightly and there was no gas leaking out as well as seeing it swell up with pressure. The vent solder looked corroded so I scratched it and found the old bad solder hole. All in all, I think they aren't a great carb....but all carbs seem to be hurting with the new fuel mixes. I love to run a decent Q-jet, but they seem to dry out the bowls in one day of setting.
Make sure you're not cheating some additional air at idle by your idle speed setting. If you crack the throttle plates a little too much, you'll start pulling through the idle and transition circuit. I'm going to second the suggestion to get a good vacuum gauge and try setting your idle mixture with it. Hook the gauge up to the full manifold side of your carb, and adjust your idle screws until you can get the highest vacuum reading possible. Adjust both screws by the same number of turns, and in the same direction. You should hear the engine "ease up" when you hit max vacuum. Adjust your idle speed down, and repeat. You are hunting for the lowest idle rpm you can achieve and keep your maximum vacuum reading steady. Once you have taken your engine rpm as low as it can go, and keep a good max vacuum reading - then you can set your idle speed back up to where you want it via the idle speed screw. Once you get the hang of it, you'll be able to adjust each screw a smidge to make up for the small inconsistencies in the carb's idle restrictions - and see the result directly on the vacuum gauge. This is all assuming your timing is good at a low rpm, which is worth a double check. Hud
Great suggestions guys! I assure you that when the sun comes up tomorrow I'll be back out there on this again. I can't bs anyone and tell them that I know the timing is "dead on" because I don't remember where we set it. I do know that previously you could barely hear it spark knocking while pulling hills. I made the next fill-up super unleaded and the valve rattling stopped so we went back and retarded the time a degree or two which let us drive rattle-free on 87 octane instead of 91. It seems like it's set somewhere around 8-10* BTDC. Also the car has always (even in the cool months) seemed like it didn't crank as good as it should after the engine was up to operating temperature. I think every other V8 I've got in the yard I can just bump the starter and they'll fire up but this engine turns several revolutions before it fires up and runs. It's always irked me but I assumed it was just "how this one cranks". I never made a correlation between the starting issue and the loading up problem. (again...this isn't my strongest area.) Thanks again guys!
You might have a faulty choke or your timing is off. Thats what it sounds like if it runs fine when its cool out. Have you tried adjusting the accelerator pump? Probaly not the culprete but might help. Look on the side where your throttle cable hooks up. Should see 3 very tiny holes with a very small cotter pin holding it in place. should be in the center now but you might want to try moving it up or down.
Do you have any kind of insulator between the manifold and teh carb? If not, do that first. Most speed shops sell what is called an insulating gasket. It is basicly about a 1/4 inch thick gasket made out of layered gasket material. They are cheap, VERY efffective and reuseable. Good luck, -Abone.
I don't have any problem getting it to turn over, it spins just fine. It just seems like it takes it a couple revolutions to "hit". I don't have any type of insulator between the carb and intake. I did ask for a "thick" gasket when I was at the parts store today and the gent behind the couter looked somewhat confused. He couldn't produce what I wanted, but since I really didn't know what I needed (aside from a thick gasket for an edelbrock carb) I guess I'm just as much of a dork as he was. I did find it difficult to not make a remark about the gent wearing a green shirt with "kermit" embroidered on it....had to be rough on him back when the muppets were popular. I had a buddy drop off a carb spacer earlier today that looks like it's about an inch thick and made from aluminum. Thanks again for all the intel guys!
The aluminum spacer will transfer heat to your carb just like the manifold will. You don't want that. Edelbrock carries thier version of the insulator gasket. EDL-9265. $14.88. You can find it at Summit, Jegs or your local speed shop. Have Kermit order it for you and don't ask him if it is easy being green... You and I will think it's funny, but he won't.. Good luck, -Abone.
I have one on a nearly stock 350 with a mild hydraulic cam in a pickup. It acted nearly the same and I fooled with almost all the things you are trying. Finally I leaned the jets and rods one step all the way around and all the trouble was gone. I have the impression the carbs are shipped slightly rich to allow for use right out of the box on hot motors without any mods without leaning the motor out and hurting it. When the main metering is too rich, it's hard to get the idle right, no matter what sidewalk experts and books tell you.
Another vote for check the fuel pressure first. The Edelbrocks seem to be pretty sensitive about fuel pressure (forcing fuel past the needle and flooding the engine at idle) and you'd be suprised how much pressure some stock mechanical pumps can put out at idle. Larry T
Agreed with alot of what's said, if you run more than 5 PSI the Edelbrocks get pretty pissy. That, and they do seriously suffer from heat, I dunno about SBC's, but Fords have an exhaust crossover that runs through the intake that seems to serve no purpose (sans stock motors) other than to piss me off and heat soak the hell outta the carb. I always block it off with some epoxy, and some aftermarket gaskets don't have the cutout for it anyhow. But those carbs get heat soaked BAD! As far as tuning, don't touch it with a 10' pole unless you got your instructions. Rod and jet changes don't necessarily make alot of logical sense some times, you have to learn how to read the Edelbrock tuning charts. The 1406 doesn't come tuned for "performance", it comes tuned for "economy". The 1405 manual choke comes with the performance tune, thats what I reconfigured mine as for a starting point. The rod/jet kits never have everything you need, I had one as a start and it probably has twice as many sets in there than when I started. I ran one on a 351C, and when I got it dialed in, it ran absolutely fantastic. If you get a consistant bog on hard acceleration try jimmyin' with the pump shot. There's not alot of flexiblilty to be had with these carbs, they only have, IIRC, 3 positions for different durations. I ended up tweeking the linkage a bit to get mine dead on. Another thing that may effect bogging is the metering rod springs, if you run too stiff a spring, it'll take less vacuum for the the rod to get pulled clear outta the jet and dump a whole buncha fuel down your intake. If you light springs, less vacuum is needed to keep the rods down. So, if you've given up some manifold vacuum with your cam, you'll need a lighter spring to keep it from dumping too much gas in too quick. There's a learning curve to figurin' these bastards out, but they can really run nice when you get them dialed in. FYI, rod and spring changes can be done at idle with a screwdriver or a nut driver... Makes for quick and easy changes!
I've had a nearly identical issue with the 350 in my 40 Merc. Edelbrock carb. I've checked everything. Have the isolating spacer. Starts great. runs pretty good (not quite as good as I think it should). I have the same rough idle issue after driving for a while. I've adjusted everything. I've been messing with it all summer. The fuel pressure and the metering rods are about the only thing left. I guess that's next. Great post and thanks for the info guys.
I think you've got a little off regarding the metering rod springs. Stiffer spring/more vacuum required to hold the rod down, lighter spring/less vacuum required.
Yep, you're right, the stiff ones need more vacuum to keep them compressed/rods down, the light ones need less vacuum to keep them compressed... I really worded that horribly . Looking back at it, I can't even figure out what the hell I was trying to say. I need to go to bed... EDIT: Oh yeah, word of advice, buy a few of the little clippy deals the hold the rods to the rod holding thing (dunno what its called and the manual's in the basement) that sits on top of the spring. They are made of anti-matter and will vanish into thin air. As much as I don't read instructions, you really need them to get your combinations correct. It's not as straight forward as Holley jets, you have to worry about the rod diameter, taper, and jet diameter. The charts are your friend!
The problem is that this starts before you can hear it. Chances are a degree or two isn't enough. I'm thinking C9 nailed it with fuel pressure, but start from scratch and insulate the carb and do the timing as well.
The fuel pressure bit may be it, but the car running good in cold ambient temps indicates to me that it's more than likely a metering rod spring problem. Nice part is, it's the cheapest fix with a pack of springs costing anywhere from $7.95 to just under ten bucks. Summit delivers carb parts quick - overnight from Reno to Kingman, Arizona last time I got jets and rods. USPS fwiw and Ohio to Georgia should be perhaps 2-3 days. Jegs is just as good if they're closer. Most speed shops stock the springs so that's a viable deal if you have one nearby. A sensitive tach can be a half-ass substitute for a vacuum gauge to set mixture, just shoot for highest rpm - it won't be much cuz you won't get much change. No got timing light? You can set timing quite accurately with the engine not running. You can't tell if the mechanical advance is working though. If it's intact and free - as in not stuck - it's probably working, but still oughta be checked with a light. Vacuum advance - if sourced to manifold vacuum (which stops overheating) will pick up rpm when reconnected. You can pinch the vacuum line and the engine will drop rpms as well. That's good for a test. Anyway, let us know how it goes. One good rule in the hot rod biz is; basics before exotica when trouble shooting....
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