Carburetor madness by Drew

[Drew Pojedinec]

Thanks for the feedback guys.  I have searched through all my Shelby data and can't find anything.  Seems an odd one, I've emailed a bunch of Shelby folks, will be curious what we figure out.

A quick look at the venturi show it to be a 780, lemans bowls, transfer tube, etc.  Part of the reason I'd like to know is due to it having a universal throttle shaft, I can change it as I have plenty of the original types laying around, but I'm not sure which one it should be.


53402698_541183333035992_2815879807361875968_n by Drew Pojedinec, on Flickr

53396379_372344490271269_9049265938259509248_n by Drew Pojedinec, on Flickr

52987299_1028000420720747_5915881493879586816_n by Drew Pojedinec, on Flickr

[thatdarncat]

If Shelby's common numbering applies, the S2 (vs S1) makes it a 427 part (vs 289) but I haven't found a specific listing for that carb, either.

My understanding of the Shelby part numbering system is that Shelby American started using “S1xx” in the 1965 model year when the ‘65 GT 350 Mustangs came online, then went to “S2xx” in the 1966 model year. In the 1967 model year when Ford started sending more Ford personnel to advise Shelby American someone realized that more closely following the Ford part numbering system would make more sense, and part numbers started changing to “S7xx”, and then in the ‘68 model year to “S8xx”. So it really didn’t have anything to do with 289 or 427. As some examples of that the picture below is a partial list of ‘66 Shelby GT 350 part numbers from the SAAC ‘65-‘67 Shelby Registry, and you can see all the “S2xx” numbers starting to appear, and of course there was no 427 or GT 500 option on the Shelby Mustang in the ‘66 model year. The “S2xx” on Drew’s carb also fits with the 1966 date code his carb has. I have notes on a couple other Holleys that aren’t on the usual production lists, but I don’t have any info on that carb, it will be interesting to see what turns up.

[Jim Comet]

Looking through the catalog I have everything listed that fits only 427 is "S2". Everything that fits 289 or 289 and 427 is part numbered "S1".

[FElony]

Please pardon my ignoramusness, but what is the trick thing about LeMans fuel bowls? Better for?

[Heo]

To not get fuelstarvation when taking a fast curve ,or so i have been told

[C8OZ]

My understanding of the Shelby part numbering system is that Shelby American started using “S1xx” in the 1965 model year when the ‘65 GT 350 Mustangs came online, then went to “S2xx” in the 1966 model year....

Ah, thank you for the education! That makes sense.

So many of the 427 parts got the S2 numbers that it looked like that was the difference.

[gt350hr]

Please pardon my ignoramusness, but what is the trick thing about LeMans fuel bowls? Better for?

   
      "Side hung" float bowls don't like to turn corners like road racers have to. The LeMans bowls were created to keep fuel slosh from causing flooding on left turns with high G loads. The center pivot float bowls that we use today followed that original design.

[gt350hr]

   The Holley date code is DEC 4, 1966 which is for the '67 model run. In following SAI's logic , the S2"C"S would be second generation Cobra ( 427) as the GT350 carburetors were S2"M"S 9510-A numbered (list 3259). The normal carburetor used on a 427 Cobra was a list 3255 and C5AF 9510 BV on the air horn. This carburetor , being a list 3948 was a later design as evidenced by the later list number. It is not a common number and one I haven't seen on an original SAI vehicle in the 50 + years I've followed and owned them. I'll look at what I have on it tonight when I get home. There is a smaller carburetor S7SK numbered that is also out there and not a "production line " installed carburetor.
     Randy

[FElony]

 The BV is shown as a race carb for a 65-67 High Riser. Lots of HR's on the road circuit?

[FElony]

Randifer, the BV is shown as a race carb for a 65-67 High Riser. Lots of HR's on the road circuit?

Thinking [I know, I know], there were not a heck of a lot of "production" High Risers in 65-67, so maybe Ford sold them over-the-counter with a single quad option?

[FElony]

 I know HR's were '64 out of DST and OTC for several years afterwards. I refer to the mustangtek site, which claims the BV as "65-67 427 Hi riser Race". The Cobra applications are shown as unverified. Why would they say Hi Rise if they are talking about a carb? Obviously, the '66-'67's are MR's, but they don't say that. A person such as myself might think that BV's were "also" used on a single quad HR, which, as I mentioned, might only have been available OTC, maybe in a package with an intake.

Why am I trying to clarify this? I have a cherry BV sitting on an equally cherry C4-G intake. The carb has a 603 date. I do not see a date on the intake. I'm trying to figure out if the carb and intake were born together, that's all. If there was a chance that there was a carb/intake combo OTC for the HR, or if there was a complete High Riser 4V DP crate engine available (I'll bet there was), then I would consider my parts to be possibly mated from the factory.

[Drew Pojedinec]

To those watching, having just restored a BE and a BV the calibrations are vastly different.
The 3255 is a very tame street calibration. The 3255-1 is a much richer calibration that elongates the idle circuit for a good bit more while bringing on the mains sooner. Conclusions are easy to draw based on this.
The -1 also has all four boosters with cutouts, it was obviously designed for a specific intake manifold.

This is info gathered by studying the calibration, running both of them with an O2 sensor and noting the circuit activity. Mustangtek is a neat resource, but like many things errors are possible.  On another note, just because a carb was designed for a specific purpose doesn’t mean they didn’t sell a pile of them over the counter or for other uses.

Thanks for looking into the mystery Shelby carb. Artis sold it to me and I’ve been trying to figure it out. When I get back home in a month I may tear into it just to see if there are any clues there.

[preaction]

Randy, could a 3255 also be stamped as a "BE" with a mid 65 date, short air horn and Le Mans bowls ?

[FElony]

Randy, could a 3255 also be stamped as a "BE" with a mid 65 date, short air horn and Le Mans bowls ?

I am not Mr. Gillis, but a 3255 is BE and a 3255-1 is BV. Randy was in error referring to a 3255 as a BV.

[gt350hr]

     The BE is a 3255 and a BV is a dash 1.  Dash one  indicates a revision to the original design and appears to be calibration as Drew said . The 3255 series is somewhat unique in that the list number was used on side hung AND LeMans float bowls , secondary metering blocks or jet plates. That was not a normal Holley practice. Because of this "I" go by the Ford number and apologize for any confusion. Simply going by the list number "could" be confusing as you can see. With most of the "in the day" Holley engineers having "passed on" , it is difficult to get the reason why this happened. While books AND the MPC may list the BV as a high riser carb , it is the carb I have seen on Q code 427 Medium Risers.



      Randy