I have a 1960, 283 bored to 302, 68 302 heads, Crane cam (sorry can't give too many specs on this but like early Duntov), and 2 Carter wcfb's. The carbs have given me months of fits. The car runs rich and no one, including several mechanics, can get it to lean down. The car hadn't run in 40 years when I got it, but PO's had tinkered with it so I have no idea how it started it's life. But it came with the 2x4's and I got it running with them, but it ran rich. I got generic rebuilding kits and went over them and reinstalled. Still ran rich. Finally got the car on the road and took it to a local respected old car mechanic. He could not get them to lean down and thought they should be rebuilt. I sent them to a recommended rebuilder who did a thorough job on the carbs. They looked beautiful and the rebuilder bench tested them on his motor before sending them to me. Ran rich so I took it to another recommended mechanic who fiddled with everything from valve lash to timing to mixture. Ran rich. I contacted the carb rebuilders and sent them back. They went over them and found a little dirt in the back carb. I changed the filter, and cleaned everything possible and reinstalled. Car ran better, but still rich. Since then I've reset valves, played with timing, tried tuning the mixture and it still runs rich and has idle problems when I run it on the road then come to an idle. I do notice that if I blip the throttle on the rear carb it sounds different than when I do this with just the front carb. When I gas just the front the engine sounds better. It seems to take the gas with less effort. Sorry I can't be more descriptive as this is a sound issue. When I gas the rear carb it is has a more restricted sound and feel, not pronounced, but it's different. Help!!! I am at wits end on this.

 

Well last time I gave carb advice I was told I didn't work on my own anyway so I shouldn't advise others.

But here goes anyway:

Why do you feel its running rich ? Black smoke, fouled plugs, funny smell, poor mileage ? Bear in mind these old WCFBs tend to run on the rich side some at their best.

First off, how is your linkage hooked up ? Progressive is best for street purposes; "shotgun" is for racing. Progressive means that the second four barrel comes in about 1/2 way through the accelerator being depressed fully, shotgun is immediate.

Next, are you ABSOLUTELY sure your choke is coming completely off as the car is warmed up ?

Does the richness occur at any particular time...like a few minutes after restarting the car after a 'hot run' (e.g. percolation) ?

Have you checked your fuel pump pressure? These old carter needle valves can be forced off their seats by too much fuel pressure. I really don't like to see much over 4-1/2 lbs but 5-1/2 lbs may work but its on the edge IMO.

There are other things to look at but these should get you started. When I first got my '61 I could foul plugs within a 20 mile drive. Turned out somebody had put the WRONG needle valves/seats in my WCFB dual quads -- they were constantly dribbling fuel down the intake.

 

I am not 100% on this as I have never fooled with the two carburetor set up but the linkage is progressive and there may only be a accelerator pump on one carburetor which may be why one responds better than the other.

If you are certain all the jets and metering rods are correct then the engine A/F mixture needs to be leaned by reducing the idle jet. This may take some special skills from someone that knows these carburetors and has the tools to tune a engine. (I am not talking about points and condenser either).

The best a carburetor rebuilder can do is make sure the correct parts are inside the carburetor but he does not know what the engine wants in terms of A/F ratio. For example on a Holley the idle feed restriction (idle jet) can be reduced to allow less idle fuel with the same amount of air hence changing the mixture A/F ratio, the same holds true with a Carter but the jet is located in the booster venturi cluster so you need to understand these things before you screw up a numbers matching carburetor.

 

I'll be reading this with interest to find out what the resolution is as I have similar rich idle issues on my 2x4s. Please keep us informed if the problem is resolved and include as much technical data as possible.

 

did you check the float level? are the floats leaking ? acc pump in one carb only.
just a few items to check for a rich condition.

 

Thanks for the suggestions. I'll try to answer each in order.
How do I know it's rich? First off the smell. Obvious rich odor that even gets in my clothes if I let it idle. Also, plugs (AC 45's) get sooty As to gas mileage, I have no basis to decide. With this engine 2x4's and 1960 parameters it isn't going to win gas mileage prizes anytime. I have nothing to compare it with for mileage. Finally, and most bothersome is the bogging down at idle if I run it then come to a light. One new observation I did not include is that when I come down the grade of my street, into my drive and take the hard right turn and up the grade into the garage, it will stutter and idle down pretty severely
Linkage - the linkage is set up as progressive with the front carb beginning to be engaged at 1/2 throttle on the back.
Choke - When it is warmed up the butterfly at the top of the carb is completely vertical.
When? - It seems to occur constantly. If I start it right up and have it in the garage it has good throttle response and idle, but it has an obvious gas smell. If I run it on the road, then I will get the poor idle, etc.
Needle/seats, etc. - The first mechanic I took it to checked all that and said they were as original. Also the rebuilder put it together to original specs.
I have not checked pump pressure - that could be an avenue to pursue, although the pump is an original AC.

One thing I'm going to try is to borrow a single 4 manifold and carb from a friend and see how it runs with that set up. That will at least tell me whether or not it is a carb problem or some thing else. But I sure like the kick of the 2x4 when I get on it. Out on the highway it really has good acceleration and is a pleasure to drive until I come to a stop. Thanks again.

 

The float level has been checked previously, but it may be an issue. I read a lot of differing measurement levels, what is the correct measurement and measuring point?

Both carbs have accelerator pumps. Floats are not leaking.

I appreciate any and all advice.
Thanks

 

You need to check that fuel pressure....

Download this manual and it will tell you how to set the floats properly: http://download.ebooks6.com/Carter-W...df-e25904.html

You can block off the front carb mount holes with a plate and jury rig rubber fuel line with clamps to the rear carb and disconnect the front line to keep gas from going all over and run for a while -- no need to remove the intake or swap carbs. This eliminates front carb issues....I've done it. If that doesn't solve the issue -- then swap carbs onto the jury rigged setup. No need to introduce more problems with a manifold swap. Cost you about $18 for block off plate, rubber fuel line and clamps.

 

I just wanted to chime in. The float levels are pretty sensitive. When I rebuilt my 2x4 carbs recently I set the float levels a little lower than the spec to try to avoid any flooding kind of issues.

The result was that when I'd floor it it would run out of fuel. I took the carbs back off and set the float level at the spec and now they run great. They really are sensitive.

With all that said, my driveability is great but on startup I still leave carbon spots on the concrete out of the tailpipes unless the car is warm. I'm not sure it's something that I can ever get rid of. The car drives great so I'm content for now.

 

The 2x4 WCFBs, when set up properly, perform beautifully. BUT, when bubba messes with them, they can become a nightmare and there are various things that can be problematic. A CORRECT, FACTORY MATCHED set of 2x4 WCFBs are identical in every way-----------------EXCEPT-----------the rear carb has a choke and choke circuit. The front carb is CAST with the provisions for a choke system, it just is NOT MACHINED for a choke system. Floats, jets, metering rods, throttle linkage (except for no choke pull off linkage on the front carb), accelerator pump, housings, etc, etc, are the same for both.
One of the most common problem areas is float adjustment. Not only does the float level need to be correctly set, BUT, WHERE BUBBA OFTEN MESSES UP, is the SIDE-TO-SIDE adjustment. WCFB floats fit VERY TIGHT in the float bowls, and if not precisely centered, the floats can rub on the side walls of the float bowls and cause the needle to not properly move up and down. Another area that can------and often is, the source of problems, is the metering rods and primary jets (there are no secondary metering rods), power piston and spring. STAY WITH THE FACTORY MATCHED spring for the power piston!!!!!!!!!!!!!!!! Bent or warped metering rods, OR EVEN WORSE, broken or distorted metering rod TIPS which do not properly pass through the primary jets--------------or don't go down in the jets at all!!!!!!!!!!!! That's another common area where bubba has tinkered. Depending on engine size, cam, headers, head type, it MAY be OK to go to a VERY SLIGHTLY larger set of secondary jets------------------BUT DON'T CHANGE THE PRIMARY JETS/METERING RODS------------------the original factory primary jets/rods work just fine!
If a WCFB has sat for an extended period--------------with old gas in it, sediment can form/harden in some of the passages and cause havoc with the operation.

I know it can be kind of costly, but Bob Kunz in St. Louis is recognized as the national 2x4 WCFB guru. I do not know of anyone who has sent a set of WCFBs to Bob and had a problem with them.

Proper linkage adjustment is important----------------BUT IT IS NOT CRITICAL! A properly rebuilt and setup carb is the main concern. For daily or normal driving, setting the linkage in the progressive setting is by far the best and most economical setting. The shotgun setting (both carbs opening together) should only be done for serious racing.

I ran 2x4 WCFBs for years on several engines, and learned most of the intricacies about them------------------got a lot of valuable advice from Bob Kunz also, and once properly rebuilt and setup, they were great. But, the urge to switch to FI finally became too much, and now the 2x4 setup sits on a shelf just waiting for the right car/engine to come along.

 

I would just add some encouragement on top of what Tom said. Once dialed in, those WCFBs are just phenomenal, and, the wow factor at cruise night is worth the trouble.

At some point you might want to quit dicking around with the local-yokel rebuilders and indeed send them off to Bob Kunz. Bob is the WCFB-whisperer for sure.

He did my carbs and I swear to you .... I have NOT touched them in 2-1/2 years of driving the car three times a week...often very hard.

 

That's perfectly normal - it's just dirty black condensate that has settled in various places in the exhaust system since the last time you shut the car off. Don't worry about it.

 

ABSOLUTELY.....you can see here where I keep two old rubber mats under each exhaust to collect that black crap. If you walk through that nastiness and then traipse the stuff across your living room carpet....the wife's head spins completely around...

 

Thanks for responding. I did not send them to a "local yokel" but sent to an outfit that was highly recommended by an internationally known Corvette restoration outfit near me (not going to name names). I'm very confident they did a correct job. I also had them checked last week by a person who restores Corvettes for a living and who has given me great advice. He checked numbers etc. and said they are original and appear to be correct in every way. So I'm left with it being possibly float levels, sticking floats, or too much pump pressure. I'm suspicious of the float issue due to the stumble I get on downhill turns etc. I did remove the screw on the side by the float and no gas came out, but that does not mean it wasn't too low, but it doesn't seem that being low would cause a rich mixture. Could it be something else entirely such as cam grind, compression, etc.? There are so many variables to consider and it's hard to be systematic in diagnosing the problem.

 

These are not Holleys..those screws on the sides are not float level indicators. Once your floats are set properly pop one of those screws and you still won't see any fuel seeping out.

WCFBs are notorious for a 'left turn stalling' condition ESPECIALLY on uphill/downhill turns. Many restorers install a bushing to fix the issue and its a well known WCFB idiosyncrasy....it has nothing to do with your over-rich problem

 

I am soooooooooo glad you mentioned that, because I forgot to point out something else.
SOME times, SOME WCFBs have a problem with the internal choke vacuum passage sucking fuel from the fuel bowl and causing an over rich condition. Carter Carburetor came up with a simple solution and published a service bulletin for the fix. Unfortunately, I cannot find the copy of the bulletin nor the illustration for the fix (I'll bet John Hinkley has a copy/illustration). The fix was simply a short length of brass tubing (about 3/4in long), tapered on each end, which is gently tapped into the carb bowl and when the carb lid was installed onto the carb bowl, it solidly sealed the choke vacuum passage so that it couldn't suck gas out of the fuel bowl. This was just one of several possible problems that occured with WCFB carbs---------------and was easily fixed.

 

Very interesting and I'm open to anything to try as I'm running out of possibilities. This sounds like a can't hurt solution. What I need, however, are details. Anyone have specifics?

 

Obviously Frank has posted a copy of the service bulletin from Carter.

 

Here is a PDF file of the fix actually installed in one of my carburetors (the red circled bushing)....this COULD be your turning/stalling problem but do NOT confuse it with your over rich running condition. They are most likely two different things....

Again, I'd check fuel pressure, float levels and ensure the floats are exactly centered in the bowls.

This manual will guide you through the process: http://handbook2.com/c/carter-wcfb-service-manual-e4402

 

Ah! Thanks Frank and John! I will definitely stop worrying about it.