carbking

Ed - be careful not to get sunstroke Jon

Was waiting to give others a chance. If you are still looking when it warms up, contact me. I am showing 3 in my inventory. I know where mine are, they are in an unheated warehouse, and the current temp is a negative 6 degrees F. Jon

As stated by others, the 3503s is the correct carb. In the "for what its worth" category (a.k.a. worthless trivia), Carter did not assign either 3508 or 3509 to a carburetor. Jon

John - if you don't already have it, here are the specs on your 3503s: Carter 3503s specifications Not a complaint, but a suggestion to the website folks: the acceptance of .pdf files by this site would be a terrific upgrade! If not possible for the whole site, even being able to include the .pdf files in messages. Jon

With the posting of individual experiences, thought I would jump in here. First, MOST of the units suggested may be made to work, some better than others. But the more important (opinion) criteria here is the familiarity the tuner has with the design of the unit (whether it is a carburetor or fuel injection), AND the availability of parts to the tuner. Personally, I am familiar with Stromberg and Rochester, and very familiar with genuine Carter. I will admit to having resources not locally available to others when it comes to Carter. First, I have custody of the remaining drawings; but I also have custody of the special lathe hand-built for Carter Engineering in 1929 to produce metering rods. So the project is my shop truck. This is a 1968 Ford F-100 to which has been fitted a mostly stock Mustang GT engine. The truck will accelerate from an idle to WOT with no hesitation, and you will never feel the secondaries, just raw power, in 1st, 2nd, and 3rd gears. In 4th, the engine needs to be above 1000 RPM before flooring the throttle. Finished the truck (as far as one ever gets finished) about 25 or so years ago. Not long after finish, I gave a ride to a youngster (25 maybe), and he proceded to give me the ultimate insult He said "I didn't know they had fuel injection for the 390, what brand are you using?" I grinned at him, and said nothing. When we got back to the shop, I opened the hood so he could see the TWO Carter AFB's sitting on top of the otherwise stock engine. Long before cell phones with cameras, but I wish I had one to have taken a picture of his face. Do how's the fuel economy? Funny you should ask. The twin 625 CFM AFB's run straight linkage, that is, both run all the time. When I finished the truck, non-ethanol fuel was readily available. At 70 MPH unloaded, the truck would average 22~23 MPG. Pulling a 16 foot tandem axle trailer with 2 John Deere 400 series lawn & garden tractors at 65 MPH, the average dropped to 16~17. When it became impossible to buy non-ethanol regular locally, I cut new step-up rods to richen the mixture about 8 percent. This dropped the unloaded mileage to 19~21. I had sold the trailer prior to this, so do not know where that mileage would have gone. The truck WAS upgraded to radial-ply tires, and the dogmatic transmission was upgraded to a 4-speed (this modification alone was good for about a 30 percent increase in fuel economy!) And yes, the carbs have been modified All of this was done WITHOUT the use of electronic test instruments, although it is possible that had I not sold the exhaust gas analyser prior to this project that I might have done a little better, don't know. No longer trying to convince anyone of anything (wag more, bark less ), just relating personal experience. Jon

Listing a number of seldom seen carbs on Ebay: Detroit Lubricator, Johnson, Marvel Indian??? Schebler part. The Miller already sold. More to come Check my listings under carbking Jon

According to Marvel Company records: The carburetor pictured is part number 10-543 used in 1916 and 1917. The 1919 Buick Model H used part number 10-526. Jon

Stromberg sold 2 different NS series carburetors to Sterling: NS-5 number A-7605 - 1924 Coast Guard NS-7 number A-7607 - 1922 model GR-6 Of course, the records, while good, may not be totally complete. Jon

Terry - the size is the "nominal" S.A.E. flange size which is never the same size as the carburetor The size 5 is a 2 inch carburetor with throttle bore of 2 3/16 inches. The size 7 is a 2 1/2 inch carburetor with throttle bore of 2 11/16 inches. I do not know if the size is marked on the side or not, I have never owned one of the NS series carbs. There are some big boats on the Lake of the Ozarks, but none as old as these. Stromberg specifies that Sterling was a customer, but no mention of the engine model. Jon

Looking to add to my collection of carburetor company newsletters. Carter called theirs "Sales & Service Summary" Holley called theirs "The Carbogram" Rochester called theirs "Rochester Newsletter" Jon

The above pictured carburetor is a stromberg NS. They came in a size 5 and also as a size 7. Rarer than winning an argument with the IRS. Desirable ONLY if you need one. Originally designed as a marine carburetor (note the upturned air intake). Jon

You might find the following links helpful: WCFB flow ratings Carter AFB flow ratings Published carb CFM ratings have actually been around since the 1930's by both Stromberg and Zenith. Jon

Dave - the JR-2A is just one of a series of Tillotson replacement carburetors; we had several which we acquired when buying large lots of carburetors from salvage yards. These came out in the early 1930's. There probably was unsold stock still around in the '40's and '50's. We recycled the ones we had, did not wish to sell them. Jon

Try these folks: http://www.linkertcarbs.com/scheblerH.html I have dealt with them. Jon

Willis - I have never been an advocate of filing weights (nor of soldering lead onto the weights). Carter offered a sufficient selection if one did one's homework. A good friend on another forum has a suggestion in his signature block of "Wag more, bark less". To complement ??? the Peterson comment, there was an article in a well-known automotive magazine which advocated replacing the vacuum piston springs in the Chevrolet 283 dual quad carbs with those from PaperMate pens. Articles were written, published, magazines were sold, money was made, and the articles were read. (wag, wag, wag ) Jon

Things worth at least considering: When Federal Mogul was still selling the downgraded redesigned AFB's, they were basically replacements for small block (up to 400 CID) Chevy engines, and calibrated accordingly. This was also true of the aftermarket genuine AFB's when Carter was still making them. There was no reason to do aftermarket AFB's for Buick, Chrysler, or Pontiac; as Carter still sold O.E. carbs for these applications. Chevrolet migrated to Holley for square bore carb for small blocks greater than the 327. I don't know what calibrations Edelbrock is using or they are available, but it is quite easy to look at original Carter specifications, as they are readily available: Carter 3921s/625 CFM (Buick 401) step-up rods used were 0.068.5 (high vacuum) x 0.063 (low vacuum) Carter 3923s/625 CFM (Buick 425) step-up rods used 0.0695 (high vacuum) x 0.063 (low vacuum) Contrast to: Carter 3720s/675 CFM (Chevrolet 327) step-up rods were 0.073 (high vacuum) x 0.063 (low vacuum) Two contrasts: (1) the obvious is that the Chevrolet rods have a significantly greater change in volume from the high vacuum step to the low vacuum step than the Buick rods (2) less obvious is that the Chevrolet engineers used a 675 CFM carburetor as the small block is capable of greater RPM and greater air demand even for less cubic inches than the Buick (3) the Buick engineers figured that the 625 CFM was sufficient for a street engine (we are NOT talking trailered race cars here). Taking the differences further, and I didn't take time to do pictures; the auxiliary air valves for Buick are of a different profile than those for the Chevrolet. Run into this all the time with Pontiac owners as the Pontiac and Buick engines will often have a hesitation when the secondary is engaged if using Chevy air valves. Does Edelbrock offer a large selection of air valves of different masses and different attack angles, as did Carter? Are specifications (air bleeds, restricters, bypasses) available from Edelbrock so they could be calibrated similiarly to the original Buick calibrations? Or is one on one's own with a tuning kit, a lathe, a vertical mill, and an AFR meter? The air cleaner question has been answered; what about the other questions? As far as the step-up piston wear is concerned, I do not know what steps Edelbrock has taken. When Carter released the AFB in 1957, the step-up pistons were brass, and the castings wore badly. After a couple of months, Carter replaced the brass pistons with aluminum ones. The aluminum pistons were machined from a softer metal beginning in 1957; thus were sacrificial from 2 months after the AFB was introduced. Step-up pistons (opinion) should at least be miked for wear (I am lazy, I just replace them automatically) at each rebuild and replaced if worn. The pistons come in the better rebuilding kits. I will grant that 425 AFB's don't grow on trees, but 401 AFB's are relatively plentiful, and can fairly easily be re-calibrated to 425 specifications. Jon

Some of the drawings still exist: Jon

REALLY NICE CAR! The model D (DX, DXR, DXC, DD, DDR) was Stromberg's first attempt at a downdraft carburetor. Basically, it is updraft technology sitting on top of the engine, rather than under it. The carburetors were problematic when new (leaking, idle issues, etc.). Once the model E was released in the early 1930's, Stromberg offered replacement E series carbs to replace all of the O.E. D series. Add that to Ed's post about the lack of carburetor restorers today who can properly restore one today (yours, by the way, is quite nice in appearance, but a coat of paint does not tell one the internal condition). If I had a car as nice and as valuable as the one pictured (I never will, Dad used to tell me I had champayne taste with beer income, and he was/is right) to tour with, I would not leave a DD-3 on my car, and yes, I can (but won't, no longer restoring carbs) restore them. I guess if it were absolutely necessary to leave the DD-3 on the engine, I would want an automatic halon system. Jon

Number 1 - make certain the choke butterfly is completely vertical when the engine is warm and you are adjusting the idle. If not, the linkage may be holding the fast idle screw on the first step of the fast idle cam. If (1) is true, look for a vacuum leak somewhere. Jon

As a young man, I was fascinated with British sports cars; it wasn't until 1979 that the "buy American" bug bit me. I bought, fixed up, and flipped several Triumph TR-3's and Sprigets, many for $10~15. each in the mid-1960's. Probably the deal that most here will appreciate started with a nice 1953 XK-120 drophead for $500, that had just been serviced. The following week I bought a running 1953 XK-120 roadster for $100, and the following week bought a non-running 1953 XK-120 fixedhead for $75. Dad used to tell me I had champayne taste, and beer income, and he was right! It didn't take long to determine that, even if I was able to buy these cars, I couldn't afford to own them, The first clue was the first oil change on the drophead. It had the "S" engine (similar to the "M"). The crankcase held 19 quarts!!! Second clue was a broken transmission mount ($100. at the local dealer!). This in 1967. Soon after, Uncle Sam called. Moved the 3 cars to my folks place for safekeeping. When I returned from Asia, they made a down payment on my house! No regrets! Jon

As a point of interest (or maybe no one is interested ), there is another downdraft two-barrel other than the Stromberg DD and DDR series made in the USA that has the parallel shafts and gears. Anyone wish to hazard a guess? Jon

Actually, they do not share the same shaft. Each throttle plate has its own shaft; the shafts are connected by the use of the gears I mentioned in the post above. Jon

One of the issues of synchronizing the throttle plates was the uneven wear of the original zinc alloy gears. Cannot be positive from the picture, but it appears your gears are still the original zinc. When rebuilding a DD-3 or DDR-3, the gears should be replaced with brass. Don't ask, I am sold out. Boston Gear used to have a full 360 degree gear with the exact correct diameter and pitch that could be sectioned to make both the primary and secondary gears. Primary and secondary is a misnomer, as both throttles operate simultaneously, but one is the control and the other is adjusted to the control. If the gears are new, and mesh correctly, one can synchronize the throttles with the carburetor off the car by measuring the clearances of the throttle plates to throttle bores at different openings. And agree with Ed, the access passage plugs must be removed so the passages can be properly cleaned. Not one of the more enjoyable carbs to restore. Just one of many items with old cars that benefit with an apprentice working with a journeyman. Jon

Jack - the only way you will find one is get exceptionally lucky! Like I said in my last post, I got the remaining original Carter inventory in about 1985, and that piece is now gone! I would be looking for used carbs with a good correct link, or get out your lathe and bending tools Jon

Part number 115-400. Different from the one in your picture. One of the more common ones, and probably the most commonly broken??? How do you break a linkage rod??? We got over 100 of them from Carter when F/M bought out Carter, and they are all gone (sold out). We got first refusal on the existing Carter inventory at the buy out, F/M didn't want it. In addition to the originals, I probably made another dozen or so when I was still restoring carbs, but no longer doing this. If you want to make one, base material is 3/32 mild steel. Jon