Dual wcfb stall problem

[Joseph F.]

1961 dual wcfb engine stalls on moderate speed turns (left or right) with engine at idle. Carbs were restored 10 years ago. Stall problem is recent. No other issues except stumble at approx. 3500 rpm with engine at wot.

[Richard M.]

Re: Dual wcfb stall problem

Joseph, Next time it stalls, pull the air cleaner lid and blip the throttles a few times and check for fuel squirts from the accelerator pumps on both carbs. You may have a stuck float on the Primary/rear carb.

I won't suggest Vapor Lock yet, but keep that in mind. A few of us have been having that problem lately.

Rich

[Frank D.]

Re: Dual wcfb stall problem

Are you absolutely sure the car is stalling on right turns too ? As these carbs are notorious for stalling on left turns and there is a fix for that...

If you are stalling out at moderate speed turns in both directions while the engine is at an idle (no pedal applied) then Rich's check with the squirters will tell you if you're pumping gas or vapors (e.g. vapor lock).

I will say that the first thing I do when my previously well-running dual quads act up is to go around and resnug the 18 air horn screws (even the one under the T-bar dust cover). You might be surprised at how loose some screws might be. Hit the 1/2" carb mounting nuts while you're at it.

If you're driving on 10 year old rebuilds it might just be time to clean/rekit both units. The needle valves eventually wear (usually a groove) and they may not seat properly at this point. Its also a chance to inspect the fuel bowls and make sure there is no crud in there. At a minimum check for leaky floats, proper float position and height/drop.

I only use Daytona Parts rebuild kits now as I like their revised needle valve setup and ethanol resistant soft parts. Used the kits on prob 10 carbs at this point...

Finally, check your fuel pump actuator arm pin - there has been a crazy spate of these things walking out of the pump housing and the symtoms can be quite bizarre and inconsistent (see red arrow in picture).

[Joseph F.]

Re: Dual wcfb stall problem

Thanks for comments. What is the fix for left-hand turn stalls? I recall some left hand problems long ago before carb rebuilds. Any adjustment or other issues using Daytona Products float valve?

[Bob W.]

Re: Dual wcfb stall problem

Frank are all their rebuild kits ethanol resistant?

Thanks Bob

[Frank D.]

Re: Dual wcfb stall problem

The left hand stall is a classic WCFB problem...here is the document on it.
And a picture of it installed on one of my carbs -- the red circled pipe in upper right hand corner of picture...

I generally just put the tube in whenever I have one of these carbs torn down just on general principle.
You can use thin tubing from any hardware store of the appropriate size. You just want a snug fit..slightly tap the tube into the passage and that's it.

Again, this may not have anything to do with your issue - this generally addresses a left turn "bobble" when turning sharply...

No special issues using the Daytona Parts rebuild kits - I've installed them in about 10 carbs now....
Yes, ALL their kits are ethanol resistant. The only other kit I'll use is a NAPA Echlin kit but prefer the Daytona Parts stuff.
Avoid the cheap, Chinesium "white box" generic WCFB kits.. A rebuild may also clear up your 3,500 RPM WOT stumble...

Here is a short primer on the Daytona needle valve/seat design: https://daytonaparts.com/daytona-carburetor-float-valve.html

[Joseph F.]

Re: Dual wcfb stall problem

Frank,
Visited the Daytona site and the valve seat design is impressive. I plan to use their kits for my rebuild. Another question: because of erratic idling, I have completely shut down the idle on the front carb and use only the rear (primary) for idle. This has made for a wonderfully consistent idle. If I were also using the front carb idle it may ease my stalling but I figure if this engine had a single carb it should be able to handle the turn situation. Also, have been running one carb idle for a time before turn/stall condition showed up. If I have problems with carb rebuild, can you recommend a shop in S.E. Michigan to go to for rebuild? Any further comments are welcome. Thanks again for your input.

[Frank D.]

Re: Dual wcfb stall problem

Frank,
Visited the Daytona site and the valve seat design is impressive. I plan to use their kits for my rebuild. Another question: because of erratic idling, I have completely shut down the idle on the front carb and use only the rear (primary) for idle. This has made for a wonderfully consistent idle. If I were also using the front carb idle it may ease my stalling but I figure if this engine had a single carb it should be able to handle the turn situation. Also, have been running one carb idle for a time before turn/stall condition showed up. If I have problems with carb rebuild, can you recommend a shop in S.E. Michigan to go to for rebuild? Any further comments are welcome. Thanks again for your input.

I run most of my idle off the rear carb as well; HOWEVER, if you don't "get into" the front 4-bbl much then you should adjust the idle screw at least enough to 'crack' the primary throttle plates open a hair so they don't get stuck from disuse. Doesn't have to be much...

As I think Duke and others have said (and I've found out on my own) the dual quads and solid lifter configuration like to idle about 850RPM...lower than that and the idle becomes sloppy and unstable.

The only folks besides me that work on my WCFBs are Bob Kunz, Chuck Smith and Daytona Parts.

Unfortunately the EPA gave Daytona such a hard time that they still do restorations of these old carbs EXCEPT for the finishes....they quit dealing with that..

You may find the carb rebuild is not that onerous a task though....

A few tips:

1) There are 18 screws in the air horn of 3 different lengths, do NOT mix them up; putting too long a screw in a hole is a sure way to strip threads.
2) Many of these carbs have extremely small anti-slosh discs (washers) around the metering rods hanging off the T-bar; do NOT lose those.
3) There is a hair-like spring that holds the metering rods in place that hangs off the T-bar, once you remove the metering rods use some blue painters tape to secure it to the T-bar to prevent loss.
4) The float bowls on these carbs are TIGHT - proper centering of the float is critical to avoid 'hang ups' while driving.
5) Adjust the float height on the inverted air horn with its gasket REMOVED; I use a 1/8" drill bit on the primaries and 1/4" drill bit on the secondaries for the adjustment...
6) Pay special attention on the rear carb that the small piston inside the choke housing moves smoothly in its bore, and, that the tiny rubber "O" ring on the BACK of the choke housing is in place when re-installing the housing...
7) Don't mix up the front and rear float pontoons...the one with the 'saddle' in it is designed to clear a throttle plate rod bump... look down in the bowls and you'll clearly see that....

Other than that its a pretty straight forward rebuild.

You can use this picture, taped to cardboard to store the screws in their proper positions (attached)...just punch the individual screws thru the cardboard as you remove them one-by-one.

Finally I have the rebuild manual for the dual quads (service manual that is) -- too big to post here; if you want it PM me with an email address.

Frank

[Joseph L.]

Re: Dual wcfb stall problem

Hi Frank

In #2, you mention the anti slosh disks. I have seen these in diagrams but do not have them on my setup. They are also called metering rod disks in diagrams I have. Are all WCFBs equipped and do you know their benefit?

[Stuart F.]

Re: Dual wcfb stall problem

Far be it for me to feel worthy to add a few of my cents into the mix, but here goes; back in the day (from mid 50's to late 61 for me), I used to setup multiple carb sets as a sideline to make a few extra bucks to keep my hobby going. I did them forusually $125. A set. My favorite dual wcfb sets were from Caddy El Dorados that I used in place of Chevy dual quads on Vettes and tri-5's using base adapter plates. They offered a couple of unique characteristics including running both primaries together and used air idle screws only on both carbs. All venturies were 1-1/8". My setups were used on the local drag strips and 1/4 mile dirt ovals (enough on the background). A couple of my tricks were as follows;

1) to help keep the floats from dragging on the sides of the chambers, I tightened the pivot pins into the float arms and let the pins float mostly in the top plate standoffs. This would ensure the floats would not slop back and forth, rather hold their adjusted centering in the float chambers.
2) I would "lap in" the butterflies in the throttle bores of the base plates using Emory cloth and light oil, holding them up to a strong light to find the high spots, working them until they were "light tight". Where possible, I would add one turn to each rat trap throttle shaft spring. When done properly, you could snap open the throttles and they would close very positively without any sticking. This went along way to ensure good positive throttle action without any hesitation.
3. I would work the primary metering rods to a needle point, adjust them by bottoming them lightly, then raise them 1/32" and lock them in place. I'm not sure what if any advantage this provided, but it made me feel good like I was really doing something.

I had a lot of customers and the last summer I did set ups before going into the Army I made lots of bucks.

FWIW

Stu Fox

[Frank D.]

Re: Dual wcfb stall problem

Bob Kunz told me he face-to-face at an NCRS regional several years back that he has put as many as 2-3 of those discs per rod on cars that are raced...IIRC they were to prevent fuel slosh. I can't imagine what other purpose they might serve; certainly not as guides for the rods as the discs move around freely.

My clone dual quads (now sold) did not have the discs either -- I didn't notice any ill effects from their absence. My 'real deal' 270hp carbs have the discs in both carbs. I flogged the '61 around the twisties at Sebring on a 'touring lap' (hit triple digit speeds at times) and never had a bobble with my discless clone carbs.

I'm not sure they are critical on street driven cars...but if they are there then I always make a point to make sure they go back in...

Stu - I'm sure everybody agrees you are plenty "worthy" to add to the mix

[Joseph F.]

Re: Dual wcfb stall problem

Thanks to all who replied. Info is usable and much appreciated. - Joe Feko