I'll preface this by saying it ran good before I touched it. So why did I touch it, you ask? Cause it was pig rich and as it gets colder, I have the windows up more and the fumes were giving me headaches in traffic and such. So, I install rods and jets that are two, steps leaner than the ones my 1405, that's 600 cfm mechanical secondaries mechanical choke, came with. It proceeds to loose a bunch of power and throttle responce, and run like shit. I try the two other logical combinations of my rods and jets, same story but a little bit better, sorta. So I decide to go back to the original set and be happy. No dice. The car will not give me a consistent idle. After I got it warmed up, I adjusted the screws for richness to where they were before, 1 1/4 out. Then I start turning the idle speed screw to get it to smooth out and idle like it did before. Real nice around 900 rpm, a nice chop cause of the RPM cam. Nothing. I can turn the screw a whole turn before the idle changes, and when it does it goes to 1500 or so. If I whack it open the idle will change. If I turn the enrichment screws, it only changes when they are all the way in. I fiddle with it for 20 minutes with no luck. I've tried everything. If it dies, it idles differently when I restart it, sometimes surging to around 2k and slowly coming down to 500 where it tries to die, or does die. When I drive it, sometimes the rpms don't drop off between gears like they should, and it bucks and surges much more on decceleration. What happened? All I can think of is the gasket on the top plate isn't sealing right. There are no visible leaks of any kind. The car has good power, but not as much throttle response as before. Nothing else other than the rods, jets, and idle settings was touched. Sorry that was long winded just covering the bases. Please help I don't want to have to drive the winter car already! And for the guys who are going to tell me to get a Holley, I'm going to look at a tunnel ram this weekend and if I get it I'm putting holleys on it, so there. But in the mean time...
Fuck a Holley. Remember the thin metal flaps you had to remove to change the rods? Loosen both of em, turn them to the side and tighten the screws back down. This will let you look at your rods with the engine running. At an idle, both rods need to be sucked into the down position. If not, the rod is hung up or, the spring is too heavy to let teh rod suck down. When you rev it, the rods will move to the up position. Give that a shot, -Abone.
Well to start with the rich smell is not because the car is rich but because of the overlap in the cam . Weaker power piston springs will help. Idle screws sometimes dont have much effect on idle because the throttle is already too far open because of the cam and such for the idle circuit to be in total control. Drilling a 1/16 hole in each primary throttle plate allows the throttle to be backed off so the idle circuit is again in control BUT----- if it ran good before it will again. It is NOT the gasket. These carbs and their cousins (The Carter Family) will run with no gasket as nothing critical is sealed by it. That is their big strength and why they tend to be more reliable than most. Make sure you dont have a bent metering rod from trying to reinstall it. That is quite common. Then get a spray type carb cleaner and remove both idle screws and spray with the little tube on the spray can down the holes. Reinstall and set them roughly at 5 half turns. It is easier to count halfs. FORGET I said FORGET how many turns they wind up being at. Set for best idle Then set about a 1/8 turn in from that when you are done. You may have to set idle mixture screws and then base idle speed two or three times till you get it where you want. Be patient. There is no such thing as a carb coming to you too rich from Edlebrock or Holley. They are always on the lean side. If you think you have trouble now wait till you get the tunnel ram! Don
Already went from the stock orange spring to yellow ones, which helped some with the bog/miss when I opened up the back two. What I can't explain is the surging and the way it will sometimes idle up really high and slowly come down. Or why sometimes it drops the revs between gears and sometimes it doesn't. Edit: Dolmetsch, you were right, it's not rich. I just ran out and checked the rods and pulled a plug. The plug was a nice toasty brown and the rods were straight with no hang-ups on the downward plunge.
Everyone I've ever known that modified an Edelbrock / Carter only made it run worse. Holleys are never right out of the box. The odd idling sounds really weird to me. The idle circuit is really simple in theory. From what you've told us, I think you have a vacuum leak outside of the carburetor. Idle racing is when it is leaking the most, idle dying is when it is somehow sealing back up and actually idling by the carb tune (which you have probably closed almost completely off to eliminate the high idle - am I right?)
I was thinking some sork of leak as well, hence the gasket thought, but there's only one hose for distributor advance. I think I've got it set around 800 rpm or so, but if I snap the throttle open with my hand, or foot, it idles differently when it comes back down.
I had that happen to me and discovered that my vacuum advance diaphram had a hole in it..! Not only did it create a vacuum leak but effected my timing as well! Changed it and it ran smooth as butter!
THROW IT AWAY, i've been dicking around with my new 1405 for almost a year now ,got it on a new 300 hp 327 and it is always run rich ,fool about 5 sets of plugs, channged the rod 8% lean , put a fuel regaleter on and got the fuel psi down to 4.5 and it still the same shit,been on the phone with them 5 times ,the last time they said they would send more rods and jets never seen them ,so the other day i took my old carter down to get rebuilt , i got it back yesterday put it on and it's running fine checked the plugs today after driving it yesterday and they look like new still ,FUCK THOSE CARBS , BOLT ON AND SET THE IDEL ,YEAH RIGHT
How's the float level? Re-check it. Is the lid gasket interfering with the floats, possibly holding them down causing the carb to flood? In either case you'll have the symptoms your describing. Junk in the inlet needle valves? Same deal....... -Bigchief.
oooh yeah ,check the floats, mine where 1 3/8 drop not the 7/8 to 1 inch like it sapostd to be , and it was not the 7/16 ether
I like Wingnutz's idea of checking the vacuum advance. If you've got one of those MityVac hand pump things, plug it in, pump it up and check the action of the distributor's breaker plate with the cap removed. Make sure it advances fully and when you release the vacuum make sure the breaker plate returns to the fully retarded position. Something could be gummed up or mechanically hanging up and making your timing go wonky. The beauty of the Carter style carbs was that they only had about six moving parts and as long as the metering rods weren't bent and the power pistons moved freely they tended to hold their tune pretty well. Get a vacuum gauge and connect it to manifold vacuum while you're working on it. If you can get it to idle, take the cover off one of the primary metering rods (or both covers if you feel really brave) and see if the piston is fully depressed. Keep a finger over it so the piston can't pop up out of the bore. If the piston is lifting, you can push it back down, (GENTLY, so you don't bend the tip of the metering rod) with your finger and this should lean things back out. Keep an eye on the vacuum gauge and watch for the relation between the vacuum reading and when the piston starts to raise in the bore and starts to richen the mixture. You should be able to alter the vacuum reading by advancing or retarding the timing, either with the vac pump on the vacuum advance or by moving the distributor. I don't know how much cam you've got in it, but if the best idle vacuum you can get is 10 inches, and the power pistons want to raise at 12 inches, it will always want to run rich at idle. This is when the weaker piston springs will help out. And remember, if you're running an auto trans it might idle at one vacuum reading in neutral, but as soon as you drop it into gear you'll lose a couple inches of vacuum from the additional load on the engine.
i got a mallory unilite with no vaccum advance on it,i was thinking that might be the problem but now with the afb i don't think that was it ,just the carb
You,re getting off track. Checking for vacuum leaks is good. A propane torch not lit but opened run around the carb base and manifold will find a vacuum leak real quick. The engne will pick right up fine. Secondly i see your name is mercury man . if you have a Fe series engine. 352 390 428 etc then it is very possible it has sucked an intake gasket. Was a very common problem. I have replaced lots of them hated the job because of the way the intake and carb wer made but it is very common. Taking a pointed punch or prick punch and making a track of evenly space punch marks around each port in the manifold when you have it apart will often cure it. If it isnt an Fe series engine then it probably isnt that.
Did you throw it away yet? If not, send it to me along with the original rods and jets. I'll get it squared away for you - barring factory defects - and send it back. No charge....
Well, mine seems to have some magic carb voodoo to it as well, or it's got/had dirt in it. After an extremely frustrating night last night, I got in it to drive it to the shop where I work, so I could tinker on it some more, and after the usual shit from being cold, it backfires and proceeds to run like a champ. It idles great now! It was idling around 1800 after the backfire, so I turned it down around 900 where it was, and it's perfect!!!! The only thing I can think of is that it got a spec of something in there somethere that made it go haywire. Thanks to everyone for the help, it is very much appreciated. I will definately be asking more questions when I get into the tunnel ram.
I have one of those Edelbrock "Carters" also. I works fine, EXCEPT, if the truck sits for a few days, the fuel bowl goes dry, and the starter has to be "run" awhile to refill the bowl. What gives? Anyone care to guess why this is happening? Thanks. Butch/56sedandelivery.
Well I guess we should turn this into the official Edelbrock/Carter carb help thread. Thats ok, everybody needs one. I'd say there is a leak and air is getting into the bowls and letting the gas evaporate, but I really don't know.
Ck engine vacuum.You have poor engine vacuum from the cam overlap,not the carbs fault.1405 do not have a manifold vaccum port,make one from the pcv fitting ,recurve and /or advance base timing to get some engine vacuum.
If I remember the way the float bowls were cast on the AVS they weren't really prone to internal fuel leaks like Qjets and some other carbs were. But after you shut off the engine and the carb heat soaks, the gas starts to evaporate and the vapors have to go somewhere. On later model stuff they got stored in the evap. cannister did but on older stuff there was usually some kind of simple atmospheric bowl venting system. Here's a link that explains a bit about a hot idle compensator valve that was used on some Carter models and could cause some erratic idle issues It shows a simple fix to eliminate the hot idle compensator. If you've still got a problem with the float bowls going dry after setting for a couple days and you don't want to monkey with the carb, just stick in a cheap electric fuel pump. It'll fill the float bowls a lot faster than cranking the engine over.
Install a simple dial fuel pressure regulator, and keep the pressure at about 3-4 psi., and most of your problems will dis-appear. Edelbrocks DO NOT like alot of pressure, and even a stock mechanical fuel pump can put out 6-7 psi. I have fixed dozens of "posessed" Edelbrocks with a simple pressure regulator.
If your area of the state is required to sell gas with ethanol in it, you can thank the fuel itself, as it evaporates while baking on top of a hot motor. When the state of Oregon mandated that it be the only (crap) fuel sold in the state, I ran into all kinds of problems with customer vehicles having fuel vaporizing out of the fuel rails of EFI vehicles, not to mention carbed cars running into the same problem. This isn't a technical reason, but it's the only thing I could come up with to explain why vehicles with perfectly good fuel delivery systems had no fuel in the rails or carbs after being parked for a day or two, no matter what the car was. Concerning the Edelbrock carbs? Good, basic design, but not exactly the best mileage carbs.
This sounds possible as well. 56sedandelivery, you might try a 1" plastic carb spacer. Mine would boil the fuel in the bowls sitting in traffic in the summer. I put one on mine and it fixed it. Might help with the heat making it evaporate, but I don't know.
It does'nt have ANY problem driving around, starting, stopping, cruising, or starting right up after a few minutes/hours; it's when it sits for SEVERAL DAYS. It seems like the fuel "leaks" or "evaporates" from the fuel bowl. Maybe an electric fuel pump would solve it; but, I still wonder what's going on. Anyone else had the same problem? MOPAR AFB/AVS 4 barrel carbs had a hesitation to them (early 70's); I thought it might be something inherant to the carb. Thanks. Butch/56sedandelivery.
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