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POCI Tech Feature

With the gaining popularity ofnostalgia racing, F.A.S.T.,NMCA and Pure Stock drag,

fast Pontiacs are very much a part of thescene. While very few original 421 SuperDuty cars are still being campaigned,there are a number of cars built to SDspecs and raced, as the rules allow forclones to run. With the cost and rarity oforiginal Super Duty carbs continuing toclimb, the need for functionally identicaland in many cases, visually identical carbshas also risen.

This article provides instructions forcloning the Carter AFB 3010, 3433 and3435 carburetors which were installed onPontiac 542991, 9770319 and 9770859dual quad intake manifolds in 1961, 1962and 1963. Carter 3010s were installed onthe ‘61 setups while the 3433/3435 car-buretors were used in 1962 and 1963.The 3010 AFBs are identical in appear-ance to the 3433/35 carbs but retained

their automatic choke components whilethe 3433/3435 set had a manual chokeinstalled on the rear carburetor.

The items needed to clone the abovecarburetors using the methods describedin this article, in addition to normalmechanics tools and readily availablechemicals, are a mig welder, oxy/acety-lene torch, dial micrometer, small metallathe and milling machines, air compres-sor and blasting cabinet with two gradesof glass beads, access to a zinc or cadmi-um plater (preferably cadmium) who iswilling to take on small jobs, and repro-duction Super Duty throttle arms andmanual choke components fromFabcraft Metal Works. Several sizes ofhelio coils may also be needed dependingupon how crusty the core carburetors areor how difficult they are to dismantle.

Finding the Right CoresThe 3010 and 3433/3435 Super Duty

carburetors have an ignition relay bosson the passenger side of the carburetorbody above the primary throttle shaft,and it is necessary to use AFBs with thisboss if the “correct” look is desired forthe clones. Very few AFBs have this bossand the ones I am aware of that do haveit are listed below, with notations as totheir suitability as the basis for the clonecarburetors (see chart).

On the Buick carburetors, the ignitionswitch boss has been machined out toaccept the mechanical ignition relaywhich those cars used. This machinedout area will have to be filled in with JBWeld. The Buicks also have no vacuumcircuits in the rear of the carb body andif ports are desired for a distributorand/or power brakes they will have to beinstalled.

The Chevy and Crusader Marine car-buretors have bodies that are identical tothe real 3010/3433/3435 carburetors,with two minor details, and in some caseshave the same casting numbers. They arethe best cores if you can find them butthey cost 3 to 5 times the price of theBuicks and are much harder to find. Asthis article is written theChevy/Crusader Marine cores cost$250-$500 each and the Buicks around$100.

The 3010 Pontiac is a real SD carband the only difference between it andthe 3433/3435 is that it has the heatchoke vacuum circuit that will have to beplugged in order to make it look correctfor ‘62/’63 setups. This carburetor is sorare however that I personally wouldnever modify one.

Another big difference between thereal Pontiac Super Duty carburetors andall of the others is that the Super Dutycarburetors have no number stampedonto the right front foot of the mainbod, as all of the others do.

All of the carburetors listed abovehave a right hand front feed air horn.The correct casting number for this airhorn on real 3433/3435 carbs is 1518.There are right hand front feed air hornswith other casting numbers that lookcorrect, however, and unless I am

By John ReederBy John ReederPhotography by the author Photography by the author

SD Clone CarbsSD Clone Carbs

Build Carter AFBs That Are Functionally Identical toBuild Carter AFBs That Are Functionally Identical tothe Very Rare ‘62-’63 Super Duty Carbs: Part 1the Very Rare ‘62-’63 Super Duty Carbs: Part 1

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cloning a set off of the Chevy3012/3221 cores I do not worry aboutthis number because someone wouldhave to lean over into your engine bay inorder to read it.

Disassembling The CarburetorsCompletely disassemble the carburetorsremoving every component. This is afairly straightforward process butdepending upon how crusty the cores arecan take several days waiting for LiquidWrench to soak into things or for thecore itself to soak in a pan of Evapo-Rust.

If the core is really dirty/greasy, etc.cleaning the entire carburetor off beforedisassembly will make the whole processeasier and more enjoyable. Use whatevermethods you normally use to cleanengine and drive train components,engine bays, etc. to accomplish this.

If a core has a lot of rust on the steelcomponents or is rusted solid soak theentire carburetor in fresh Evapo-Rustuntil all evidence of rust is gone; whichusually takes a day or two. The Evapo-Rust will dissolve the rust but will notharm the aluminum or brass. Afterremoval from the Evapo-Rust rinse thecarburetor off with a water hose andthen blow it out and off with com-pressed air and allow it to dry. This stepalone sometimes frees everything up andthe screws will now come out, the throt-tle shafts will move, etc.

If you have never completely disman-tled and reassembled an AFB before Iwould strongly recommend taking pic-tures of each carburetor before and dur-ing disassembly for future reference.Take pictures of all four sides, of boththe top and bottom, of the inside of thebody before the boosters are removed,and of the underside of the air hornwhere the floats are installed. Make anote of which boosters were installed ineach side of the carburetor body, andfront and rear. Take several pictures ofthe passenger side throttle shaft linkagebecause you will need to refer to themwhen putting that linkage back on. Takepictures of these linkage components on

both carburetors and record the num-bers stamped onto each part of both setsof components. Carter used several ver-sions of the passenger side linkage com-ponents over time and while they may alllook alike to the casual observer they arenot identical and if mixed up duringreassembly will often not work together.The components installed on both coresshould be the same but these carburetorsare more than fifty years old now andmay have been apart before and thenreassembled with incorrect componentsfrom another AFB.

Also, write down the numbers castonto the boosters; they should be pairedand the numbers should differ by onedigit right side/left side. The acceleratorpump nozzles should have casting num-ber 264 on them.

Although hopefully not the case withyour set it may be necessary to buy threecores in order to make two complete,correct, carburetors.

Now take screw drivers, dental pics ifnecessary, a small punch if necessary,and take the carbs apart. I have foundthat a manual impact driver is the bestway to remove the screws from the ends

of the throttle shafts on the right side ofthe carb, or at least to break them loose.

This tool can also be used to breakthe air horn perimeter screws loose, andthose holding the boosters down, but ifthe screws in those areas are so tight thatthe impact driver is needed I will firstapply Liquid Wrench liberally around thescrews and boosters and allow it to soakin for a day or two before using theimpact driver. Grind screw driver tipsdown so they fit the screws. If a screwslot is damaged, recut it with the edge ofa small file. If a slot is so badly damagedas to be useless, take a small pair of nee-dle nose vise grips and remove the screwby grabbing the head and turning it out.

Once a screw moves at all it is usuallygoing to come out but it may take a dayor two or three of pouring the LiquidWrench on, letting it soak, and thenworking the screw back and forth slowly,walking away for awhile, and then work-ing it some more, to get it done.

Sometimes it has taken me a week tocompletely dismantle one really crustycarburetor core. Sometimes it is also nec-essary to use a plumbers propane torchand apply heat in order to remove some

2507/2800 ‘57/’58 Buick Poor- boss is cast wrong and front view of carb is incorrect

2840 ‘59 Buick Very good or fair- view from front is correct but on half of

them the boss is cast wrong; those with the correct appearing

boss are identical to 2982

2982 ‘60 Buick Very good- probably 4/5ths of the clones I have made use of this

as the core carburetor

3010 ‘60 Pontiac NASCAR Excellent- used on ‘61 setups but extremely rare

3012/3221 ‘61 Chevy 348 Excellent- body is identical to real 3433/3435 and in some cases has

the same casting number

2955 Crusader Marine Excellent- same as 3012/3221 but rarest of all

Core Original Application Suitability as Clone

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POCI Tech Feature

The arrow at the upper left points to the hot idle compen-sator circuit, lower left to the ignition relay boss, and lowerright to the outer choke vacuum circuit. All of these circuitsneed to be plugged with JB Weld stick epoxy or with alu-minum rod per the instructions in the article.

2840, 2955, 2982, 3010, 3012, and 3221 all look like the topbody from the front. On the bottom is 2507/2800 typewhich looks wrong.

components.Remove the throttle and choke plates

screws by grinding off the peened-oninner ends flush with the shaft with aDremel small round stone. You will scarthe shafts a little when doing this but it

can’t be helped. If it looks like you’ve ground the

inner end completely off and the screwwon’t move then grind it off some more.If the screw moves but is giving you stiffresistance then grind it off some more.

These screws are brass, are thereforeweak, and you don’t want to break oneoff. Once started the screw ought tocome out with only minor or no resist-ance.

After removing the first primarythrottle shaft I would recommend taking pictures of the idle speed cam and springwhich rests against the inner throttlearm, which you can later refer to whenreassembling the carburetors.

When removing the jets having thescrew driver fit the slot in the jet is anabsolute must because the jets are brass,are often very tight, and once you injurethe slot in one you usually have to eitherdrill the jet out completely or ruin it byusing a backout to remove it.

Sometimes you can put a screwdriverin the slot and whack it straight downhard with a hammer and that will breakthe tension on the threads and allow youto remove it, but not always. If the jetsare the size you will use or are smalleryou may want to consider just leavingthem in and when smaller drilling themout to the size you will need.

If the accelerator pump well checkball assembly will not come out, use aDremel with the small round steel bitand eat away the brass holding thechrome check ball in until it falls out.You can then insert a backout in thebrass check ball housing and remove it.

If you do break a screw off all isn’t

The body pictured at the top is the 2955/ 3010/ 3012/ 3221/ 3433/ 3435 type andthe ignition relay boss was never machined out. The middle body is a 2982 andthe boss on the one shown has been filled in with JB Weld. Half of the 2840s looklike this one. The boss on the top and middle bodies have the correct look. Thebottom body is of the 2507/2800 type and the boss appears wrong in that it wascast without the gap at the top separating it slightly from the main body. Theother half of 2840s look like this one. Notice the large vacuum ports in the rearof the top and bottom bodies. The 2840/2982 bodies do not have this port.

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lost because you can drill it out and re-tap that hole, but it makes things somuch easier if you do not have to dothis. The holes can also be helio coiled,including those for the jets. When I haveto drill out these little screw shanks, re-tap holes, helio coil, etc. I have to use themilling machine table with the x and yaxis and center drills to do it. It is impos-sible for me personally to get dead oncenter otherwise.

If you end up completely ruining thethreads in one or more of the holes in athrottle shaft you can drill the ruined

hole(s) in that shaft one size larger, uselarger diameter screws to hold the throt-tle plates in, and turn the heads on thescrews down so they will go down intothe recesses in the shaft originallymachined out for them. When done cor-rectly this is hardly noticeable. Due tothe ignition switch boss the throttleshafts on the Super Duty carburetorsand clone cores are longer than theshafts on almost all other AFBs andmust be saved if at all possible.

Much of the above of coursedescribes worst case scenarios, which

thankfully, are rare. The overwhelmingmajority of cores are fairly clean andcome apart easily with one or two jetsnormally being the hardest componentsto remove.

At this point I separate the steel com-ponents from the aluminum castings.Almost all of The steel componentsincluding the throttle shafts will eventu-ally be pickled and sent out for cadmiumplating. The springs, if plated, must bebaked immediately following plating orthey will develop a condition calledhydrogen embrittlement and will eventu-

This shows a 2982 throttle shaft and arm with the originalpeening filed off. The shaft has been inserted into a long9/16 x 3/8 drive socket held in a vise, and is being drivenout of the throttle arm with a punch. A 1/4 drive socket,11/32 on 2955/3012/3221 type arms and 9/32 on 2840/2982arms, is placed in the open end of the throttle arm to keepit from collapsing while the shaft is driven out.

Plug both ends of the choke shaft channel on the frontcarb airhorn with aluminum rod. Remove any chokestoves, which some airhorns have, and fill the resultinghole with JB Weld.

Rear of two bodies showing distributor and power brake vacuum fittings. The 2982-type bodies do not have a vacu-um port in the rear of the body, so these will have to beadded for distributor vacuum and power brakes, if desired.Carefully locate the middle of the rear carburetor base and drill and tap with 17/64th drill and 5/16 NF24 tap. Place dis-tributor vacuum behind the right, passenger’s side, throttleplate or the fitting will jam up against the distributor. Donot drill completely into the throttle bore for either fitting.

The arrows on the left and right point to both ends of thechoke vacuum circuit. The one in the middle identifies thespark port. Block off the inner choke circuit and sparkport, if it has been opened up, with plugs of JB Weld.

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POCI Tech Feature

I use a mig welder to add length to the the bare shaft. Atleast .125-inch must be added to a 2955/3012/3221 shaftand .225-inch to a 2982/2840 shaft. Be careful and add onlyto the end and avoid filling in the original flats which clockthe throttle arm. Turn the added length down to .370 on a metal lathe.

ally break. The aluminum castings will bethoroughly cleaned and then the bodiesand air horns will be modified as neces-sary. The floats, choke and throttleblades, and metering rod pistons, springs,and wire metering rod retainers will beset aside and cleaned before reinstalla-tion.

CleaningGet the aluminum castings absolutelyclean both inside and out. Outside clean makes them look pretty and insideclean makes them perform right.

Use whatever method you use toclean greasy engine components and thelike to clean the carburetor bodies, airhorns, and boosters. I do not have anultrasonic cleaner so I go through amulti-step process using gasoline, ace-tone or lacquer thinner, and then run thebodies and air horns through a full dish-washer cycle. Yes, the wife lets me dothis.

Following the dishwasher I take a sec-ond pan of either acetone or lacquerthinner and repeatedly squirt the solventthrough all of the internal passages ofevery casting, including the boosters,with a brake fluid bulb. When cleaningthe passages in the boosters this secondtime I run appropriate diameter weldingtorch cleaner wires through the airbleeds, idle jets, etc.

It is at this point that I chase the

threads in every screw hole. Do not omitthis step. If you do not do it now youwill invariably have to do it on one holeor another when you reassemble thecarbs. It is rare when anything needs tobe helio-coiled but it does happen and itis at this point that I do that.

Modifying the Carburetor BodiesFill the ignition relay boss in on theBuicks cores, both top and bottom, withJB Weld stick epoxy. Do this by stickingone of the throttle shafts in the body sothat a smooth portion of the shaft is in the area where the boss is, and mix andfill the openings with the JB Weld filler,turning the shaft as the first applicationhardens. It may take several applicationsof the JB Weld to bring the machinedout areas up flush with the bottom sur-face of the body and top of the ignition relay boss but when filled andsanded/filed off you will want thoseareas even and flat. If the JB Weld youare using doesn’t match the color of thecarb body don’t worry about it becauseyou are going to daub aluminum coloredpaint on those areas anyway.

The real 3433/3435 carbs had thevacuum circuit to the choke bodyblocked off with a rounded aluminumplug, and you will want to duplicate this.Make your plugs by cutting off a 1/2-inch long piece of 3/16-inch diameteraluminum rod for each core and then

round off one end of each rod. Nextdrill the outer choke vacuum passage oneach body with a 3/16-inch drill bit andthen glue the plugs in place with JB Weldtube epoxy, turning the plugs as youinsert them. Leave the rounded off por-tion of each rod barely sticking out afterinsertion. Now seal off the inner end ofthis passage with a dollop of JB Weld.The inner end of the passage is shown inone of the illustrations.

Cores that were originally made for anautomatic transmission car had a hot idlecompensator mounted above the sec-ondary throttle bores between the tworear boosters. Block off the circuit thatwas under the hot idle compensator withJB Weld epoxy stick epoxy, filling about1/2-inch of the passage at the top, orwith a 1/2-inch length piece of 1/4-inchdiameter aluminum rod glued in placewith JB Weld. On the Chevy andCrusader Marine cores a large vacuumport in the rear center of the body is alsofed by that same circuit and you do notwant to block that off. Look for an openhot idle compensator circuit in everycore you buy. Someone may haveremoved the hot idle compensator atsome point, did not block the passageoff, and then wondered why the carbure-tor would not run right.

Some bodies also have what is called aspark port on the underside of the bodyat the front edge of the passenger’s side

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The total length of the flats beyond the shoulder should be.325-inch, which will leave .090-inch of shaft standing proudof the throttle arm before peening. You can take off the lastfew thousands, and square the end of the shaft, on a tabletop disc sander.Then recut and extend the flats on a milling machine.

primary throttle bore. This port is some-times capped with a metal plug, some-times it is open, and sometimes peoplehave uncapped it and elongated theopening so as to feed manifold vacuumto the vacuum port in the front of thecarburetor. If that passage is open plug itwith JB Weld.

On the Buick cores fittings for distrib-utor vacuum and power brakes can beplaced at the back bottom edge of thebodies if desired. When installing a dis-tributor vacuum port place it behind thepassenger side rear throttle plate. If youput it in the center rear or behind the dri-ver’s side throttle plate the distributorcap will interfere with it. Place the vacu-um brake port in the center rear of whatwill become the front carburetor. Forboth ports drill 17/64th diameter holesand tap with a 5/15 NF24 tap. Brasscomponents to create the fittings neededcan be obtained at any good hardwarestore, NAPA, etc. To my knowledgenone of the Super Duty cars had powerbrakes but to accommodate customerswho do I make up power brake lines thatlook like what is found on Pontiac Tri-Power setups.

Some of these carburetors have sub-stantial corrosion on the bottoms of thecarburetor body. While unsightly thisposes no harm as long as the float bowlsand passages feeding fuel to the boostershave not been compromised. Fill these

corroded areas with JB Weld tube epoxyand use files and sandpaper to take theseareas flat and even with the bottom of the carburetor. Filling these areas maytake several applications of JB Weld, fil-ing and sanding between each applica-tion in a manner similar to using bodyfiller on a car body.

Modifying the AirhornsThe choke shaft bore on the front carbu-retor air horn on the real SD carbs wereeither never drilled out or were pluggedwith aluminum rod.

You can plug both ends of this boreon the air horn you will use for yourfront carburetor with two 5/16-inchdiameter aluminum rods. Slightly roundoff one end of each rod. Glue theseplugs in with JB Weld tube epoxy turningthe plugs as they are inserted in theirholes, leaving the rounded end just stick-ing out of the bore on each side.

Some air horns also have a brasschoke stove protruding from the rightupper rear. Take a pair of pliers andremove this tube and then fill the cavitywith JB Weld tube epoxy, smoothing offboth the inside and outside surfaces tomatch the contour of the air horn.

Bead Blasting and SealingAll of the processes you used to cleanthe bodies and air horns will more thanlikely not remove all of the stains and

discoloration the castings have picked upduring their lifetime. Original AFBs didnot have those stains and discolorations.I bead blast the carburetor bodies,airhorns, and boosters twice; first at 100psi with medium beads which removesall of the discoloration, then a secondtime at 50 psi with the finest beads I canobtain.

For the second bead blasting I useonly fresh beads and this leaves the car-buretors looking as close to NOS, in myopinion, as you can get and not really bethere. Some customers have insisted thatI have their bodies and air horns treatedwith alodine or other coatings ratherthan bead blasting them and I humorthem, but in my opinion the two stepbead blasting looks far better.

Following bead blasting I blow outevery passage in the carburetor bodies,air horns, and boosters, repeatedly, with150 lbs. of air pressure. During thisprocess I will hold the bare bodies upsidedown and bang them, hard, on a flatpiece of 2x12 pine board to make sure Idislodge any and all glass beads, and thenblow them out again. I again run appro-priate diameter welding torch cleanerwires through the air bleeds, idle jets, etc.in each booster to make sure all glassbeads are removed.

I will now daub aluminum coloredpaint on the tops of the JB Weld fillingthe ignition relay bosses, and after this

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POCI Tech Feature

Left to right is an original 2982 throttle arm, a 2982 armthat has been modified to become a Super Duty inner arm,and then a Fabcraft inner arm. Notice the slight bendsplaced in the long portion of both the modified 2982 andFabcraft arms.

Left to right are an original shaft and arm from a 3012 car-buretor, a bare shaft after removal of the throttle arm, ashaft that has been lengthened with a MIG welder, then onethat has been turned down and had the flats extended on alathe and a milling machine, and finally a shaft with SuperDuty inner and outer throttle arms sitting on it ready for peening.

paint dries seal (paint) the bodies, airhorns, and boosters with Eastwood’sSatin Clear for bare metal, which willprevent oxidation. I do not spray theSatin Clear on thick but instead just dustit on.

Sometimes the air horns will end upslightly darker than the bodies or viceversa, or one body will not exactly matchthe next one in shade. This is because thebatches of molten aluminum used whenpouring the castings differed slightly incolor.

Installing The SD Throttle ArmsThis is the hardest part of the process.Place each primary throttle shaft in a visewith aluminum jaws, with the throttleblade slots at a 90-degree angle to theplane of the jaws so you do not crushthat area of the throttle shaft, and grindor file off the peening holding the origi-nal throttle arm on. Then place a long 9/16 x 3/8 drive socket in the vise, placethe throttle shaft in it, and drive the shaftout of the throttle arm. Before drivingthe shaft out put some kind of spacer (Iuse a 11/32x1/4 drive socket on 3012type arms and a 9/32x1/4 drive socketon 2840/2982 arms) in the open end of the throttle arm so you do not collapse itwhen driving the shaft out.

If you do not use a spacer and do col-lapse the open area you can open it backup later, but it is a pain, so use a spacer.

If you are using Buick cores keep thethrottle arm as it will become the innersuper duty arm. If the cores are3012/3221 Chevys the inner arm off ofthem will become the SD inner arm.

Now you must add onto the end ofthe bare throttle shaft and I use a migwelder to do this, making several passesto add what I need. On the Buick shaftsyou will want to add at least .225-inch tothe length of the shaft and on theChevys, at least .125-inch. The addedlength is necessary so you will have metalwith which to peen on the Super Dutythrottle arms.

After you’ve added onto the end of ashaft you will have excess metal and willneed to turn the weldment down to .370diameter and then recut the flats whichwill clock the throttle arm. When recut-ting the flats be sure you do not get intothe original area of the shaft; ie only cutwhere you added metal. Fabcraft makesthe slot in their SD arm a tad wider thanthe slots on the original throttle arms onboth the Buick and Chevy cores but theresulting gap between this slot and the-flat areas on both sides of the throttleshaft will be filled with metal during thepeening process.

Now grind down the end of the shaftoff so you end up with .325-inch ofmetal beyond the shoulder where theinner arm will rest. This will leave .090inches standing proud of the outer arm

when both arms are placed on the shaft.Before peening modify the inner arm

as shown in one illustration. If youacquired a new inner arm from Fabcraftit too must be modified to match themodified arm in the illustration.

You are now ready to peen on theinner and outer Super Duty arms. Nowagain place the shaft in a vise with alu-minum jawed vise, straight up, throttleblade slots 90 degrees to the plane of thejaws, and place both the inner and outerarms on the end of the shaft.

You do not want the shaft standingtall in the vise as that will just increasethe odds that you will bend it during thepeening process, but you do want toleave some distance for the shaft to slidedown into the jaws- and it WILL slide- asyou peen the throttle arms on with asledge hammer. VERY IMPORTANT-you want the throttle arm clocked so thatthe throttle plate screws go into the shaftfrom the bottom of the carburetor whenthe throttle plates are closed - check thisorientation several times before peeningbecause once peened you cannot undowhat you have done without consider-able effort.

Tighten the vise as tight as you cantighten it. Now take an oxy-acetylenetorch in one hand and a sledge hammerin the other hand, and peen the SDthrottle arm and inner arm onto the shaftby heating the nub on the shaft proud of

Page 35

Shown is the end of the shaft heated cherry red with aoxy/acetylene torch. Not shown is the 5 lb. sledge hammerin my other hand. I usually peen the new arms on in four orfive cycles of heating the end of the shaft just to the point ofmelting, and then smacking it rapidly with the hammerthree or four times fairly hard - straight down. If you have never done something like this you might want to turnsome 3/8 steel rod down slightly and then practice peeningwashers onto the ends of several of them. You will haveonly one chance to get it right when you peen the SuperDuty arms onto the modified shafts.

Place the shaft upright in a vise with aluminum jaws, leav-ing room for the shaft to slide down some during thepeening process. Close the vise jaws as tight as you can. Besure to place the shaft in the vise with the throttle bladeslots perpendicular to the plane of the jaws so that area ofthe shaft will not be crushed.

the throttle arm just to the point of melt-ing and then hit it straight down with thesledge hammer. You will have to repeatthis several times before the arm ispeened on and you may have to loosenthe vise once or twice during this processand move the shaft back up. As you peenthe throttle arm on you will be forcingsteel into the gap between the slot in theFabcraft arm and the flats you machinedonto the shaft. The peened on arm lookspretty bad immediately upon completionbut after bead blasting and plating willlook very nice.

At this point I pickle all of the carbu-retor’s steel components except thesprings, including the throttle shafts, andsend it all to the cadmium plater.Everything but the idle mixture screwsshould be plated silver. The idle mixturescrews originally came both silver andblack so their color is your choice. Ifdesired you can dress the screw heads onscrews that will be visible when the car-buretor is reassembled by tapping thedisfigured heads down with a small ham-mer and then recutting the slots with afile. Or just buy new philister headscrews which is what I do. The newscrews I buy are zinc plated whenreceived so I pickle them and have them

plated silver cad along with the othersteel components. The springs, if plated,must be baked immediately followingplating or they will develop a conditioncalled hydrogen embrittlement and willeventually break. If the plater you areusing does not have an oven in which tobake the springs they can be thoroughly

cleaned, or glass bead blasted, and paint-ed silver.

Next month, we will finish up theprocedure, straightening bent throttleshafts, modifying the choke shaft andeven providing jetting suggestions forengines from 389 to 496 cubic inches.Stay tuned! SS

This is what the shaft and arm will look like immediately following peening. Itlooks bad now but it will be pretty after bead blasting and cadmium plating.

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POCI Tech Feature

Editor’s Note: This month, we finishup John Reeder’s excellent two-partseries and even provide some jettingrecommendations. We appreciateJohn’s contribution and hope it helpswith your own project.

Straightening A Throttle ShaftSometimes during the process of peen-ing the new throttle arm on or during theplating process a throttle shaft willbecome bent slightly and will thereforenot want to go into the carb bodysmoothly, or after being installed withthe throttle blades tightened down willnot turn easily. The bend can be identi-fied by holding the shaft against a steelstraight edge with no plates in it and thenwith the plates installed and the screwstightened down, which often alters thebend or can even straighten the shaft.The bend is usually in the area of the slotwhich was cut for the plates, but notalways. Once identified put the throttle

plates in the shaft, no screws, and placethe shaft in an aluminum jawed vise withthe point of the bend at the edge of thevise jaws and with the remainder of the shaft standing proud.

Now use a small hammer or screwdriver handle and lightly tap the exposedportion of the shaft toward the sideopposite the bend. You do not need tohit it hard. Now reinstall the shaft,including putting the plates in and tight-ening them down, and see if the shaftnow turns easily in the carburetor body.If it does not repeat the straighteningprocess until the shaft does turn easilyafter being installed. Sometimes it takesseveral attempts to get a shaft straight,and it can be necessary to straightenmore than one bend.

Modifying The Choke ShaftGrind or file off the peening holding theoriginal choke arm on and remove thearm. Now drill and tap the bare end of

the choke shaft with a #36 drill bit and6x32nc tap. Drill at least ½-inch deepand tap threads in until the tap stops.

Now you will want to grind down thearea of the shaft that has the flats, whichclocks the choke arm, so the end of theshaft beyond the shoulder is .040 incheslong and is just below the surface of theFabcraft arm when it is placed on theend of the shaft. This will allow thescrew holding the arm on to hold it tightwith no slop. I grind the end of thechoke shaft down on a table top beltsander with a sanding disc, going slowand repeatedly checking the amount ofshaft protruding beyond the surface ofthe arm. Go slow because the chokeshaft is brass, which is soft, and if youremove the flats completely you will haveruined the shaft.

Now install the Fabcraft choke armon the shaft with a 6x32 screw, usinghigh strength Loctite threadlocker. Next,dress the other end of the choke shaft sothe linkage arm components for that endof the shaft can be easily installed. Forsome reason for me these componentsare easily removed but then always goback on with some difficulty.

I now retap the holes which acceptthe screws that hold the choke platedown on with a 4-40 tap. The originalholes are large enough so that no drillingis required if you take your time with thetap.

Now place the choke return spring onthe shaft, place the shaft in the air horn,and install the choke plate with 4-40x3/8brass screws using high strength Loctitethreadlocker.

Checking & Cleaning the Floats,Throttle and Choke PlatesCheck the floats by filling a clear glass2/3rds full of water and heating it in amicrowave for 40 seconds. Thenimmerse each float and watch for bub-bles. If there is a leak you will see bub-bles instantly.

If there are no bubbles then there isno leak. Immersing the floats inEvaporust overnight will make them

By John Reeder Photography by the author By John Reeder Photography by the author

SD Clone CarbsSD Clone Carbs

Build Carter AFBs That Are Functionally Identical toBuild Carter AFBs That Are Functionally Identical tothe Very Rare ‘62-’63 Super Duty Carbs: Part 2the Very Rare ‘62-’63 Super Duty Carbs: Part 2

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POCI Tech Featurelook like new, or they can be polishedwith a Scotchbrite pad and Brasso.

The choke and throttle plates can bemade to look like new by cleaning themand using the same two step bead blast-ing process as the carburetor bodies andairhorns.

ReassemblyReassembly is straight forward and is theopposite of taking the carb apart. I beginby first installing the throttle shafts andthrottle plates. Do not forget to installthe idle speed cams and springs on theprimary shafts before putting the shaftsin the bodies. I install the throttle plateswith steel screws and high strengthLoctite threadlocker. Use 6-32x3/8screws for the primary throttle plates and 6-32x5/16 for the secondary plates.Actually I do not put the threadlocker onthe screws until after I have flow testedthe carburetors and you may also want towait until the carburetors are completelyassembled before you apply the thead-locker.

If it becomes necessary to remove thethrottle plates after threadlocker isapplied it will take heat to make thethreadlocker turn loose. To accomplishthis hold a plumber’s propane torchflame directly on a throttle screw forabout five seconds and then use a screw-driver to break it loose and remove it. Ifyou attempt to remove the screws with-out heat you will break them off guaran-teed. I do not attempt to peen the insideend of the screws. If your engine bayever gets hot enough to make the screwsturn loose on their own you’ve got amuch bigger problem than the screwscoming out.

When tightening the screws just snugthem up tight, the threadlocker will holdthem. Do not try to be King Kong withthem as they are very small screws andyou may break them off.

Installing the passenger’s side linkagepieces on the throttle shafts can be achallenge if you’ve never done it. My rec-ommendation, again, is to have takenpictures of that linkage before it wasremoved, front and rear, from above and

upside down.Next, I install the auxiliary air valve

over the secondary throttle plates, andthen the boosters and accelerator pumpnozzle, making sure to install the squarebrass check valve under the pump noz-zle. The screws holding the boosters andaccelerator pump nozzles in have lockwashers so no threadlocker is used onthem.

After that, install the jets and acceler-ator pump well check valve. The jettingand metering rods installed by Carter inthe original 3433/3435 carbs were .089primary jets, .070 secondary jets, and.054x.060 metering rods. The correctsize metering rods are no longer availableso I use ones that are close as possibleand Edelbrock’s #1438 at .052x.058,#1461 at .057x.065, and #1441 at.052x.062 are good choices. Actually, youcan use any size metering rod and thenuse “piRsquare” to determine the appro-priate primary jet size. The secondary jetsize will not be affected. The factory cal-ibration was for a 421 cubic inch engine.Calibrations I’ve put in carb sets for var-ious size engines are shown in the chartabove.

I determined the above jetting using aformula I have developed over time andthe engines these carburetors wereinstalled on should be running slightlyrich. I asked the customers in every caseto watch their spark plugs and if therewas any indication of running lean toinstall larger primary jets, or smallerdiameter metering rods, and please tellme what they have done for my futurereference. No one has ever gotten backto me and told me they have changed

their jetting so I would think that youshould be able to get in the ball park withinitial calibration for your engine byextrapolating off of the above chart. Myformula is driven by cubic inches only;cam, head flows, etc. were not taken intoconsideration.

I reinstall the old style acceleratorpump well check valves with the chromeball bearing, checking that they flow onlyone way and in the correct direction witha small plastic tube and lung pressure,before installing them. In my opinion theold style valves work better than the cur-rent version with the little brass triangleshaped plate type valve. Install the bowlbaffles with the concave bends to therear of the float bowls.

Install the idle mixture screws andsprings by turning each one all the way inand then backing it out 1 3/4 turns.

Install the idle speed screws andsprings and turn them until they justtouch the idle speed cams on the throttleshaft and then turn the screw on the pri-mary carb in two more complete turnsand on the secondary (front) carb onemore complete turn. This will set the car-buretors up idling off of both the frontand rear carburetors so fuel will continu-ously be flowing through both of them.

Reassemble the tops by placing the airhorn gaskets on first, the needles andseats next, and then the floats. Most cur-rently manufactured needles and seatshave a .085 diameter hole in them to feedfuel through, where the old originalswere .10. Edelbrock makes a high-flowseat with a .110 diameter feed hole whichis item EDL-1466. On a cruise/show car.085 seats are fine but if you are going to

389 .085 .070 .054x.060421 .092 .070 .052x.059462 .094 .073 .062x.068480 .095 .069 .058x.069494 .087 .078 .050x.057

AFB Carburetor Jetting Recommendations (Dual 4-Barrel Applications)

Cubic Primary Secondary Metering Inches Jets Jets Rods

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POCI Tech Feature

This picture shows the four steps necessary to install a man-ual choke arm on the rear carburetor choke shaft. Left toright is an original choke shaft with the automatic chokearm still installed, next a shaft has had that arm removed,then next a shaft has been drilled and tapped to receive theSuper Duty type manual choke arm, and fourth a shaft has had the SD arm installed. The fifth shaft is a real SD chokeshaft and arm that has been cadmium plated. As you can seethe real arm has a square wire stop and if one is desired forthe Fabcraft arm it can be fabricated out of square brassrod.

This picture shows the steel components removed frompairs of AFBs both before and after plating. The springs mustbe baked immediately after plating or they will take onhydrogen embrittlement and may break.

Be sure to install the fast idle cam and spring on both pri-mary throttle shafts before installing them in the carbu-retor bodies. Here are views of the cam and spring fromboth the top and bottom of the throttle arm.

Sometimes a throttle shaft can become bent slightly dur-ing the process of peening the SD throttle arm on or dur-ing plating. Determine where the bend is by holding theshaft against a steel straight edge. Then place the shaft inan aluminum jawed vise with the point of the bend at theedge of the jaws. If the point of the bend is in the areawhere the throttle blades will be installed, and it usually is,place a throttle blade in the shaft where the jaws will holdit. Now gently tap in the shaft to straighten it. Just tap it;that is normally all it will take. It may take several attemptsto get the shaft straight and a given shaft may be bent inmore than one place.

go racing install seats with the .110 holesor the fuel pump may not be able to keepup with the engine all the way throughthe quarter-mile. On some seats otherthan Edelbrocks it is possible to drill thefeed hole out to .110 and I do that regu-larly. After drilling the hole out debur itboth sides by hand spinning a slightlylarger drill bit in reverse against the edgesof the hole. Set the float levels at 7/32-inch and float drops at 23/32-inch.

Now, lubricate the accelerator pumpand pump well with light oil, install thespring and pump in the well, and install

the air horn. Tighten the screws aroundthe circumference of the airhorn in threeor four steps starting with the centerfront and rear screws and then workingto the the sides of the carburetor body,both sides. The choke cable bracket usesthe forward screw on the passenger’sside top as well as one of the screws thatoriginally held the automatic choke bodyon. At this point it may be necessary tobend the choke arm slightly to get it toclear the choke cable bracket when thechoke is closed.

After the air horn is on tight, install

3/8-inch fuel inlets, Edelbrock itemEDE-8090, tighten them, and check theneedles and seats for function by holdingeach carburetor upside down andattempting to blow through the fuelinlet; the floats should have closed theneedles and seats with the carburetorsheld upside down so you should not beable to blow through the fuel inlet. Nowturn the carburetors over and you shouldbe able to audibly hear the floats dropand now be able to easily blow throughthe fuel inlet. Actually you can performthis check before the air horns are

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POCI Tech Featureinstalled but it is good to do it again afterinstallation.

Now install the springs, metering rodand piston assemblies, and metering rodcovers in the tops of the air horns. Ifyou forgot to chase the threads for thelittle screws that hold the metering rodcovers down do it now. I once ruined atop by not chasing the threads in one ofthose holes, and the little broken offscrew shank was too small for me to getout.

Install the accelerator pump arm, “S”link, and accelerator pump rod. A correctaccelerator pump arm for these carbure-tors will have only one hole, not three orfour. The “S” link should be installed toappear as the letter “S” from the front ofthe carburetor. The correct rod will becaptured at the bottom end, where it isinserted into the throttle arm, by the car-buretor body, and held with a smallspring clip at the top where it is insertedinto the pump arm. You will see rodsinstalled with the bottom end held withthe spring clip and the top end with aneat copper clasp; this looks pretty but

the rod is actually installed upside down.In terms of function however it makesno difference.

Finally install the passenger’s sidechoke linkage components and adjust asnecessary so that the secondary throttleshaft is locked out when the choke plate

is closed.Be sure to install plugs in the front

and rear (if any) vacuum ports beforeinstalling the carburetors on your engine.

That’s it, you have now created a setof 3010 or 3433/3435 clones!

SS

A finished set passengers side view. The lead photo shows the same systemfrom the drivers side.