2X4 barrels FLOOD engine on turns

[Excaliber]

What kind of carbs are you guys with dual four barrels running?

I've got Holley 660's, center squirters. The carbs flood the engine bad:
1. In ANY corner.
2. Under moderate stopping.

Great for drag racing, but I want to go in circles (as in SCCA).

Replace the manifold with a single carb?
Replace the dual carbs with something else?

I THINK I have a high riser manifold.

[Bruce Edwards]

Float level checks out ok? Vents installed in the front and rear bowls?

[What'saCobra?]

Carb problems can be fixed easily, cheaply and correctly, but you can only pick two from this list of three variables.

The most effective fix for road racing is deep-six the dual set-up (sell it and the manifold to a collector/poseur or a psudo-drag racer) and go with a modern Holley HP series 850 or perhaps a 950 if you really have a hot cam, flowed heads and big pipes. Other carbs will do, but Holley's racer carbs come perfect out of the box. Call Holley, tell 'em exactly what you've got and purchase accordingly. Listen to their view on current manifold choices, unless you have a serious and well-justified preference.

If NASCAR thought two 4bbl carbs was effective, they would all have them after petitioning the France family for a rule change.

Like all carbs, final jetting (leaning her out) is up to your choice of exhaust color, chrome pipe blueing, the importance of another 1/2 a tenth of a second less ET and piston-melt risk. Otherwise, don't screw too much with it. ***** to Holley if it isn't absolutely perfect and follow their instructions to the letter...

Short of that suggestion, there are several culprits that may be solving your problem. It isn't clear to me if you have center-pivot carbs currently. These later designs provide for correct fuel bowl levels, when set up correctly, despite any two-axis accellerations (left/right or fore/aft). Without these it is a lot of luck and fetteling to get them close and they may never be quite satisfactory because of inherent design flaws that cause them to be accelleration sensitive.

So, what to do cheap.

First, get the specs and mechanically set the fuel levels in the bowls. The usually means bending the float tang until the tang or the float is a specified distance from the bottom of the bowl. (While you are at it, make sure there is no fuel INSIDE the brass float, which will cause the level to be excessive high even if the tang bend is correct.) Grab a pair of the clear bowl plugs to visually ID that the actual levels are below the lower lip of the plug threads. Adjust & test.

If no joy, clean the bowl inlet valve seats and if the shut-off valve pins are steel, consider installing Viton-tipped pins. These work great and will tolerate higher than normal fuel pressures and still seal. While you are here, clean out the valve seat orifice. Test.

If no joy, certainly try lowering the bowl fuel levels a bit by closing up the tang adjustment dimension, both in case they are too high and you might cheat a solution thereby. Test.

If no joy, install a fuel pressure gauge and check fuel inlet pressure. It should not be much above 6 psi or so, including when you rev the engine (if you have an additional mechanical pump). Install a Holley pressure regulator if much above 6 psi. Measure, adjust and test.

Bruce from Winter Park is correct, there are fuel vent extentions you can install that will reduce the splashing of fuel overboard into the venturi(s) during various accellerations. Buy the Holley Catalogue, read, learn and get the bits. Install and test.

If no joy, check the linkage and ensure there is a little initial play or clearance upon throttle application. If it is zero lash, engine movement from shifting, braking and variable torque will cause the accellerator pump(s) to dribble or even squirt unintentionaly. While you are here, make sure the pump levers have an initial loose fit on the pump lever cam. Vibrations can cause the pump(s) to dribble. Also, linkage can twist with accelleration and engine movement and open the throttle a little, enough to cause the pumps to dribble. Set them up loose and see if it helps. Measure, adjust and test.

Anyway, while this is far from complete, you get the idea. There are other little things you might screw with, like raising the idle rpm a bit to help the engine clear when you stomp on it just before the apex, but they are either too diddley or trying to fix something that ain't designed right in the first place.

Oh yea, and dump those little Stellings air filter CHOKES if you have them. They are trash and eat fuel and hp.

These suggestions are offered along with good luck wishes and are not intended to be a complete treatise or sequentially perfect.

[Ron61]

Ernie,

Now you know why a lot of the NASCAR racers went from the dual fours to a single four. I had a friend who had a 1964 Galaxie with the dual four setup and even on street tires I could make it mess up on turns. I had another friend with the same car and engine except he had the single four and it wouldn't mess up at all turning either way.
Whatsa cobra has given you the best list of options to follow, but I would go to the single four and keep the duals for show purposes if you want to impress people at shows.

Ron

[What'saCobra?]

In reviewing my post, I noticed my 5 letter word for griping or complaining to Holley if their carb was less than perfect was exorcised and otherwise scrubbed.

OK by me, but such a mild and proper use of the word need not incur such wrath. The word "bee eye tea see 8ch" was not used to describe any of my ex-wives, nor my lovely editor/employer or even the bar-maid that stole my cell phone.

How will we ever refer to our female whelping dogs or even those guys who act badly and remain pseudo-fatherless to this day...?

Perhaps my post is just a victim of mindless computer flushing (isn't that in New Jersey?) or like Janet's teat, forever consigned to the dust-bin of secrecy.

[Chaplin]

Ernie,
This sounds serious. Tell you what, I'll give you $17.5k for the car as is. I would have given you $20k, but it sounds like the car is defective.

[clayfoushee]

Whatsa, .....not to worry. It's just an automatic program installed to keep things moderately clean. Most public sites have them installed these days. No offense taken by anyone I'm sure.

BTW, Ernie, I agree with single carb set-up. My single Holley in an SO as described above is bullet proof under all conditions.

[Dsprint2000]

Ernie - I'll give you $20k.....

David

--- sorry Chappy...

[Ron61]

Ernie,

I'll give you $50 for the dual four barell setup. Also I will throw in an extra $10 for a gallon of gas.

Ron

[Excaliber]

Bummer, I love the look of the duals, but if I want to race sounds like single carb is the way to go.

I've covered the basics but did get some additional ideas to check for. The carbs have no choke, there is no place to add a choke even. The 660's center squirters are pretty radical carbs. No power valves either. Tall bowl vents, got 'em. Brass floats with spring assist (good floats), rubber needle tip externally adjustable float level lowered BELOW specs. 7 lbs fuel pressure (gauge mounted on carb inlet).

However, ZERO clearance on linkage, "touch" them and they squirt HUGE quantities of fuel. I'll loosen the linkage, back off the accellerator pump shot and re-jet from 75 to 70's.

I have a hunch I'm treating the symptoms and will eventually have to go to single carb to do the SCCA thing.


How 'bout $35K down payment and I'll set you up on a "easy payment plan" for the rest?

[Clois Harlan]

Ernie,

I had the same problems you are experiencing with my 2X4 set up. I fought it all last year and could never remedy all my problems. Last fall I sold the manifold, carbs, air cleaners, and an extra set of filters for a fair price. I now run a medium riser with a Demon 750 and have sold all my cornering problems. The 2X4's would go in a straight line like a stripped A$$ Ape but were really junk on a road course.

They sure do look cool though.

Best luck with whatever you decide to go with.


Clois

[clayfoushee]

Don't worry Ernie.....if you keep the hood closed while racing (recommended), no one will see that you don't have dual carbs

[Zoom This]

Originally posted by Excaliber


What kind of carbs are you guys with dual four barrels running?

I've got Holley 660's, center squirters. The carbs flood the engine bad:
1. In ANY corner.
2. Under moderate stopping.

Great for drag racing, but I want to go in circles (as in SCCA).

Replace the manifold with a single carb?
Replace the dual carbs with something else?

I THINK I have a high riser manifold.

Ernie....I have an 850 Holley double pump w/mechanical secondaries for sale with chromate plating that is only 6 months old with 2000 miles on it. It's really too much carb for my 418 stroker on the primary side. It has #80 jets on all four corners, #35 accelerator pump nozzles. The metering block has been modified so it will not drool gas back into intake manifold after run hot. If you are interested, $450 will get it to you. See my gallery for pictures.

Zoom

[Excaliber]

Hey Zoom, that might be the ticket. With the "twins" I've got 1320 total cfm and it DON'T feel like to much. The motor is "radical".

Still considering my options but like Clois said, looks like single carb in my future.

Now about that manifold under the carb,,,,,,,,,

My twin FORD alloy manifold part number: C4AE9425F

I assume this is a high rise because:
1. No throttle linkage "boss" on rear.
2. No heat cross over plumbing.

Can someone check that number?

[Jerry Cowing]

Excaliber,

Don't pay too much attention to all the dooms day comments. You can get your dual 4 barrels to work just fine in the turns.

Everything that What'saCobra? said is correct. However, he left out one very important item. If you don't have the correct floats in a dual 4bbl setup, it will never stop flooding when making hard decelerating turns.

You need to replace all 4 of your floats with the black Nitrolyte floats Part #116-1. Then adjust your floats so the float level is about an eighth of an inch below the leveling sight hole. No gas should come out of the hole until you rock the car side-to-side hard. The gas should splash out of the hole, but not seep out. Don't forget to always rev the engine after each needle valve adjustment to empty the primary or secondary float bowl and let it refill at idle before you re-check the levels.

Instead of using the "vent baffles" which have a tendency to interfere with proper float operation, you can also use a "vent screen" sold by Holley through Jegs or Summit Part #26-39.

[kountzecobra]

Have to agree with Jerry. With tuning, dual quads will run at least as good as a single quad. Most folks don't want to invest the time to do it correctly. They can be made to perform without any spits, sputters, or bogs when turning or going straight. If you want to give up and take the easy route, then replace the intake with a single and one Holley. Then when you open the hood, you can let out a big yawn and tell everyone you USED to have dual quads under there! It is worth the effort.

[Excaliber]

I never heard of the vent baffles, I'll check that out. Following the advice offered here:

I worked on them a good part of the day and there MUCH improved. Went from 75 to 68 jets. Adjusted the accel pump to be a little loose on initial throttle travel. Set the floats BELOW the standard level. And the BIG one, replaced one needle\seat that was leaking and keeping that float level high.

Not sure I'm ready for SCCA but it's WAY better on the street at least! Next stop is somewhere to get the fuel air ratio checked, worried 68's might be to small for 1320 cfm air flow.

[Rick Parker]

The trick is to adjust the floats at High Tide. Then they won't be affected by the altitude as much

Rick

[kountzecobra]

I knew you could help it Ernie. Just keep at it. Its worth the effort.
Jet size should be in the ballpark. Maybe 67 or 66? Just make sure you don't get a lean surge at cruise speeds. Idle mixture is VERY important up until hi-midrange speeds. Adjust at idle with a non-damped vacuum gauge. One carb at a time, back and forth until each is best. I usually back off of idle speed on the carb I am not adjusting at the time. Adjust linkage correctly too. And most of all: have fun!

[What'saCobra?]

Don't worry, you are not flowing 1320 cfm, but the carbs are supposedly capable of that rate, if everything on them is perfect, the moon is in the best position and you have at least standard conditions.

But, if you are going to race up MaunaLoa or whatever, 68's might be OK. At sea level, it all depends on your exhaust temperatures, particularly on the most distant ends, left and right. I would always prefer to know exhaust temps real time. Drill a hole in one and stick a sensor in there, make some runs and watch the guages. But the O2 sensor can tell a lot also.

Pistons are not terrible expensive, but a pisseur to buy just one if you have a unique set-up and you didn't buy 2 spares at the time. And the piston eats other stuff if it really lets go rather than just holes.

Jerry is right, there is a set of Nitrolyte floats that are shaped to reduce the excess float "sink" when decelerating in a corner. It doesn't happen when accelerating because you are open throttle and full on the main jets. The lateral axis accelerations are the problem when the fuel starts to climb up the bowl wall and the average fuel level in the bowl, as measured along the old float axis, drops, causing the valve to open and admit excess fuel. Again a good idea which tries to correct a serious problem caused by a lousy (for road-racing) initial design in the first place.

By the way, some folks have no problems because their cars don't generate enough lateral G's on their street tires. Race tires and genuine race driving really raise the ante and will demand a more thorough solution.

With that super tight linkage and no lash you would be surprised at how much excess fuel was dumped in the manifold, particularly if you could see how much the engine really moves left and right on its mounts as you slam and jerk the drivetrain around and transition from downshifting/braking each gear then back to WOT.

Lot's of good ideas today.