Carter AFB running too rich, but only on one side!

[Knebel]

Hi,

i have a problem with my Carter afb 4 bbl, its running rich but only on one side of the Carb it seems like (Well, one side of the carb produces black sparkplugs, the other is fairly ok but dark sometimes). It had (Primary and Secondary) .098 and .095 Jets with 71/47 Metering Rods and pink Springs when i bought the Car, this made all Plugs pitchblack.
I now have .095 and .092 Jets with 75/47 Metering Rods and same Step up springs installed (.092 and .089 with 73/52 rods looked too lean but made the Plugs look equal). The Car runs great and dosent Idle rough or lumpy, it just makes some Plugs black and I see that its on the Cylinders fed by the right side of the Carb.

I got a Chrysler 318 with edelbrock 318/360 Intake and a Carter AFB on it. The Engine also has a Cam but i have no idea which (I didnt build the Motor and the previous owner didnt know either). I already have a Pertronix Ignitor and a MSD A6 Installed. I read that it could be the Ignition Coil so i ordered a Flamethrower to see if this fixes it.

So far i Checked:
Dizzy Cap looks good and i cleaned the Contacts.
Vacuum is around 18 Hg
Initial Timing is at 13°
new Fuel Filter
new Spring loaded Floats (and Float adjusted properly)
Choke opens full
Got a Colortune Sparkplug and checked with that, nothing spectacular to see, idles righ at the Change from Blue to Orange flame but looks like its missing sometimes and dosent show a change when i turn the Idle Mixture Screwes, the Flame is supposed to go from orange to white ect. but i can hear the engine reacting to the change, so i guess the Idle Mixture Screws work okay. (With the Colortune you can look into the engines Fuel burning process and see the flame!)
I had the Carb apart several times and blew through every hole with carb cleaner....

One thing, I had to drill small holes in the Primary Throttle Plates to get them to close far enough to cover enough of the transit slot and get it to idle where it should.

Anyone got a Tip on what else to check? Thank you!

 

[commando1]

Hi,

i have a problem with my Carter afb 4 bbl, its running rich but only on one side of the Carb it seems like (Well, one side of the carb produces black sparkplugs, the other is fairly ok but dark sometimes).

Impossible. Unless I'm not understanding what you said.

 

[70NPORT]

Impossible. Unless I'm not understanding what you said.

Yea, I stopped right there too.

 

[Knebel]

Ok so... i know it sounds weird.

Basically, the 4 Cylinders which get the Mixture from one side of the Carb are too rich. The Cylinders which get the Mixture from the other side are okay or at least leaner. For Example: Cylinder 1,4,6,7 are Rich, 2,3,5,8 are leaner. Its weird isnt it or do i have a twist in my brain? I mean, im looking at the Plugs and see the Black ones and the Gray ones!?

the Other thing is that i get only 8 MPG out of it..... thats in my eyes not enough for a 318 in a 68 Fury III

 

[Knebel]

Here, i think you can get the Idea of what i am talking about. The two top left ones were also wet, its Cylinder 6 & 8 i believe! This is after a 8 Mile drive. Not really any hard acceleration involved.

 

[1966newport]

vaccum leak on side that isn't rich?

 

[commando1]

Its weird isnt it or do i have a twist in my brain?

One side of the carburetor does not feed one side of the engine.
That's like saying you poured water into one side of the kettle while making soup and then ate the soup only from that side.

Now, to solve the problem........
Some plugs showing rich, some plugs showing good combustion, and some plugs burning lean:
Valve seals or piston rings are worn.
In your case, because they seem grouped to one side, it is simply a matter of coincidence.

 

[Knebel]

Thanks for the Answers so far. I have found two other things.
Fist, some of the Bolts on the Intake manifold werent tightend!? -fixed
The Carb Leaks Fuel into the Chambers where the weights of the Secondary Butterflies are. I cant really see where the fuel is coming from but i can only Imagine it eiterh leaks through the gasket from the Secondary Venturies or the Air horn Gasket. So i decided to Order a new set of gaskets and see what it does.

I was out for a drive today and the differences in the Plugs arent that much anymore (not black/white) some are just more tan colored and others more Grey-ish. The Tan Colored ones are the Ones which feed out of the Left side of the Intake Manifold. Its not One Cylinder bank which does it, its the left side of the Intake. It's one of those "Split type ones"

 

[360dusted]

Knebel is right the whole idea of a dual-plane intake is to separate each side of the carb to half the cylinders so the vacuum signal is improved. I think you found your problem with the loose intake bolts. The leak from the carb you describe sounds like you have the floats set too high; go through the carb and put new gaskets in then set the float level to spec. Also if you don't currently have one I would recommend a 1/2" (or 1" if there's still hood clearance) plastic spacer to keep the carb from getting too hot and boiling the gas inside; this is a common problem with Carter/Edel style carbs and will make the engine idle rough and possibly stall in stop-and-go traffic not to mention worsen the gas mileage.

 

[1978 NYB]

Did you figure it out yet?

 

[Knebel]

Hi all,

i have sort of figured it out actually! I replaced the Gaskets in the carb and after that the car wasn't running anymore at all. It could not keep an Idle and just died after a few seconds. After a lot of taking apart and setting floats ect i found out it was a Idle mixture problem. I had them turned out 1 turn and it run fine. Now, with everything cleaned and sealed, I had to turn them almost 3 turns out to keep it running. Took it for a small ride and noticed that it would surge when keeping a steady throttle, its jetted pretty lean so i have to change that again. But: All the Sparkplugs look the same now.

The New Ignition Coil i had ordered from Amazon went right back into the box and returned, had a dent and ratteled inside, nice packing Job Amazon!

 

[commando1]

Glad to hear you are getting this problem solved. Carbs. PITA...

 

[Knebel]

Ok so i have the engine running. idles pretty smooth and i got rid of the "cruise surge". But now it stalls out when turning sharp right corners. Even at low speed just going in the neighbourhood. Anyone an idea on this?

 

[commando1]

FLOATS and/or vent tubes.
Easy one. Now give us something hard.

 

[Knebel]

Thanks Commando! Would you say I have to set them higher? To have more fuel in the bowls? I currently have them set to 5/16 on the spring loaded needles.And the drop slightly under 1 Inch. Should I set them to 3/8th? Thank you so far with you help!

 

[commando1]

To be honest, I really havent a clue what your specs should be. Somehow you'll have find some specs for them.

< Sent from my tablet >

 

[360dusted]

You are on the right track the spec calls for 3/8" distance from the float to the main body when resting (closed) on the needles. This actually lowers the level of fuel in the bowls, what's happening when you turn is the fuel spills out the booster from the level being too high...

 

[Knebel]

Thank you, 360dusted. It makes a whole lot more sense to me when i know what happens! In the Carter AFB Tuning Manual it just says that high float level can cause stalling ect. But then i find five different specs for it. from 11/32 to 13/32 and 5/16 to 3/8 or 7/16.... ect.

 

[Knebel]

I set the floats to 7/16. That has worked, it dosent stall anymore when turning.

Now i had to set the timing to 19* initial to have it idle and run smooth, it ran with 12* initial too when the carb had all the problems but i had to turn the idle screw a lot and uncovered the transfere slot too much. Looks like Someone already limited the mech. distributor advance with some sort of crappy filing job :/

I remember checking the timing when i bought the car and it was somewhat 20ish and the idle was at 1300 in park and dropped to 900 in drive. Now with my work done on it i can set it to 900 in park and have it idle at around 700 to 750 in drive (that also covers enough of the transfere slot, and i already have holes in the throttle blades). And i actually have response fom the idle mixture screwes.

I currently have the Idle screws set to 5 1/2 turns out and get around 14" HG vacuum reading. Plugs look grey to very light tan. Engine runs okay with that but i can turn them out a little more to smoothen things out. I can get it to 15" Hg but then i have the Idle mixture out 8 or 9 turns and that cant be right!? When i turn them in to around 3 turns, the car dies and will not keep idle. Is there a way to modify the idle circuit to be able to turn the screws in more without making it horrible lean? or should i just leave them how they are and dont bother having them out that far if it runs?

Other than all that it drives great and dosent seem to have any hesitation or anything, i could probably ho a step richer in the metering rods but thats all just the fine tuning. Thank you guys so much for the help!

 

[360dusted]

Maybe the idle circuits are a bit dirty? My 383 runs great with only 2 turns (as in 2 full 360* rotations) out on the mixture screws but that is at 6000' elevation... Unscrew the mixture screws all the way out and then spray the holes out with carb cleaner