BeachinVette

I replaced plugs and wires. When I have the car Idling it pops "back fires" through the exhaust. I have adjusted the fuel and air on the carb, and it seems to help for a short while. Then the popping comes back. The exhaust smells like it is burning real rich, you can almost taste it. It will burn your eyes and smells bad. No smoking though. I have adjusted both screws from 1 turn out to 3 turns out the further I go out the popping will quit for awhile, but the exhaust still smells rich. The car will run good. But that popping sucks. It is an Edlebrock 1406 600 cfm. Does Lars rebuild and set up Edlebrocks ? and how much does he charge?

Thanks in advance
Bob

Lt1er

You need to read the owners manual on how to change the jetting. It's also on line if you don't have the manual.

BeachinVette

Lt1er
Do you have the link? I havbe been looking for it and can`t find it.
Thanks
Bob

ScubaJKD

http://www.edelbrock.com/automotive/index.html

:seeya

MassVette

I've had the same problem with my 2 NEW Edelbrock 1405's on the 502. They were matched and re-jetted for the 2x4 setup.
The carbs would cough every once and a while, coming onto the acceleration circuit. Thought it was bad gas or plugs; last week on the interstate, it backfired again, and flames came up the windshield, as smoke poured out from behind the car. Luckily, there was a rest area just ahead, and when I opened the hood, there was a FIREBALL coming off the motor. After squirting it with a fire extinguisher (which I ALWAYS carry in a 'Vette!), we got it ramped to the garage and found out that it was the front carb where the fire originated! Right now, it looks like either a defective float, or needle and seat. I think Edelbrock is having problems with these carbs, because more people I have talked to since have told me about flooding on hot starts, and backfiring problems...just like mine was doing.
:mad :mad :mad :mad

BeachinVette

MassVette
Wow that is not good news, As I was trying to dial in the carb the other night I had a big fireball come up out of the carb also. I have done somemore tweaking and I have not had that happen again. It is little popping like it is burning fuel in the exhaust pipe. I can see the blue flame cominout of the pipes, mostly out of the left side (right side from looking from the back).

Bob

LemansBlue68

You mentioned that you replaced plugs and wires. Are you absolutely sure that the plug wires didn't get put back on out of firing sequence? I had a friend with this same problem. He swore up an down that he put the wires on right. I double checked and sure enough, two were crossed.

BeachinVette

LemansBlue68

I will double check them. I have put them on here wrong in the past. I alway`s overlook the simple stuff
Thanks
Bob

7Bob3

Bob

If the plug wires check out, you may want to check the float level.

Vetterodder

If the problem started after changing plugs and wires, that's where you should look. Otherwise, it sounds more like a timing problem (ignition or valve) to me. Late ignition timing will cause unburnt fuel in the exhaust (causing the popping) and can also cause a backfire through the carb just as you described. As already posted, recheck the position of your plug wires as they could cause the same problems if incorrect. If these problems only occur at idle, it's unlikely that the carb's jetting would have an effect.

BeachinVette

Update
I checked the wires they were correct. I checked the timing (ignition) it is correct. I did a Bubba thing my nieghbor said "sounds like a stuck valve Pour some tranny fluid down the carb that will un stick it!" Well the mosquitoes are gone but the popping is still there. I can really smell the exhaust thick, It is like when you are stuck in the snow and you get the muffler side to push and it chokes you. But no smoke.
What do you all think??
Bob

dman535

I have a 750 cfm unit that behaves the same way. I am trying to score another square bore carb to try on the car to see if it is really carb or its ignition. The inside of my air cleaner shows evidence of backfire. At lower rpms I can hear the pops in the exhaust and sometimes it feels like the carb is loading up. I talked to the folks at Edelbrock, didn't really give me a whole lot to go on. I have played with springs, jets and rods but have not tried new needles or seats. Will report back when I swap the carb out.

Blake-73

I had this problem with my 1406. Fine print in th manual said that runing
12 hg or less manifold vacum (due to large duration cam) would require a different step-up spring. I changed my springs over to the orange ones and it was fine after that. I also changed metering rods to 1 stage rich, but that was mainly for performance. Try changing the springs to orange. Very easy to do.

Blake-73

Apeiron

Sounds like it's flooding. If you use a mechanic's mirror to look down into the carb you'll probably see fuel dripping in. Could be the float is set too high, the needle and seat are dirty, fuel pressure is too high, return line on the fuel pump is blocked, etc.

BTW, you put ATF in the oil to free a stuck lifter, not in the carb. :)

8T1-7T9 BIONIC VETTE

Do you have a fuel pressure regulator?.....If so .....what is your pressure set at?

LemansBlue68

I guess I'm still stuck on the possibility that you've got a missfire due to an ignition related problem. Another possibility is a cracked porcelain insulator in one of your "new" plugs. It is so easy to drop and damage these things and not notice and the damage may not even be visible (It could have happened in shipment or at the store where you bought the plugs). The effect would be that the spark jumps through the insulator instead of across the gap. The cylinder may still fire, but intermittantly. Does the engine run rough too? Try pulling one wire at a time and see if the engine idle gets rougher. If you pull a wire, and the idle doesn't change, you may have a miss in that cylinder.

Is there a way you can change back to your old carb to see if that changes anything--or possibly get your hands on a similar carb that you know is good and try it?

Another thought is to take a look at your plugs after the engine has run for some time. Look to see if they all have signs of carbon on them. If one's clean, that cylinder probably isn't firing. You may also find one that's wet, which would indicate your carb is dumping fuel somehow and fouling the plug.

I hope this helps. I always tend to skip the easy stuff, too, and then find out later that it was something simple.

Good Luck!!!