3259-1 comparisons

[Drew Pojedinec]

Since the subject of carb parts came up recently.....

I still had these pics on my phone, I had 7, 3259 variants in my shop last month.
I compared two from forum members.

In this collection we see the three vs four digit date code.
Also the thickness of the choke horn casting.
Note the secondary squirter boss

[Drew Pojedinec]

Metering blocks are double stamped on later versions.

[Drew Pojedinec]

Not always, but many later baseplates are fatter where secondary shaft is housed.
Pump spring and bolt are different on original vs later

Early throttle plates had smaller numbers stamped

[Drew Pojedinec]

Original choke and throttle shafts had a distinct pattern where the die attached the levers.
Later is blockier.

[J_Speegle]

Thanks for sharing Drew

[2112]

Thanks for sharing Drew

+1 

[Dan Case]

Drew and I compare notes. He can only cover some points in these little text boxes. I keep a spreadsheet of engineering design levels and the parts you can see different without having to dismantle anything.  Between late fall 1964 and 1967 Holley® made many engineering and or supplier changes.  Most have learned by now that there was not "a 3259" but a family of them.


GT350 Carburetor Version 1: Take a final 1964 version of the R-2668A (1963-64 427 Ford C3AE-9510-B) assembly, change fuel bowls to base assemblies from ones from a 427 4V High Riser carburetor, change to .0110 inlet orifices and DuPont® Viton® resin rubber tipped inlet needles, swap in GT350 appropriate fittings, add an external fuel transfer line and you have a prototype R-3259 for a GT350. Deface the original production stampings on the air horn and remark it as a "3259". That is exactly what the Holley Custom Shop did for Ford/Shelby. The one that we know still exists was produced in February 1964 as a 427 Ford production item. When SFM5R002 was first tested it seems to have used one of the prototypes, I won't go into the evidence here for that car.

GT350 Carburetor Version 2: The assembly design was signed off to production December 2, 1964 as the R-3259A design level. Just two production runs were made in December 1964 with most assemblies made during the second run.  While based on the R-3259 Prototype some parts had changed since the prototypes were made. Said another way December 1964 assemblies have different bits than circa summer to maybe October 1964 prototypes. The major change was the secondary metering block design to improve the air fuel ratio curve under wide open throttle conditions.

Carburetor Version 3:  When mass production started in January 1965 some more details changed and now the assembly was designated R-3259AAS.  In just the two weeks since the last run some parts were changed to something else or otherwise revised. Said another way January 1965 assemblies have different bits than December 1964 ones. The two major changes were the primary metering block design to improve the air fuel ratio curve under most conditions and a new design main body.

Carburetor Version 4: During the 1966 MUSTANG GT350 production run Holley released the R-3259-1A model. The secondary operated vacuum system was redesigned to change timing of W.O.T. under hard acceleration to improve fuel curve and general performance.

Carburetor Version 5: Before June 1966 the main body casting design was changed to create the R-3259-1AAS model. The common place to find one of these is a 1967 Shelby GT350 Mustang or as an over the counter accessory until Shelby shut down his parts business.

Carburetor Version 6: Ford Advanced Vehicles modified a few R-3259-1AAS models to work specifically with GT40 MKIII street cars. (7 cars to the best of my knowledge. I have one never apart in my collection.)

Otherwise, Holley went through all kinds of small parts changes as mentioned above, generally speaking every six months or so changes were integrated into production.

[Bob Gaines]

My head hurts but I want all of the hurt I can get. Thanks guys.

[sfm5]

Thanks Drew & Dan, I didn't know that I didn't know these things until I learned them from this thread. 

[Drew Pojedinec]

I don't have all of the data and history....
Just figured I had a bunch of these in at one time, so be handy to note some external differences.
Seeing as how the two look similar but one is worth 3x what the other is makes it worthwhile to see them both.


Dan, One question that maybe you can answer.
3259's and 3259-1's have a pretty much exact calibration fir the most part through time. Air bleeds etc are pretty much the same.
For some reason about half of the 3259-1's in 1967 have a massive idle feed restriction.
Typical is .069 idle air bleed, .031 idle feed restriction.
On about half of the 67 dated ones you have a .069 idle air bleed and a .040 idle feed restriction.
At first I thought it came from a few over enthusiastic racers.... but I've now found a dozen just like that. Exactly .040, too common to be a fluke.
Any idea how, or why they would be so oversized?

Thanks
Drew

[Dan Case]

I don't have all of the data and history....
Just figured I had a bunch of these in at one time, so be handy to note some external differences.
Seeing as how the two look similar but one is worth 3x what the other is makes it worthwhile to see them both.


Dan, One question that maybe you can answer.
3259's and 3259-1's have a pretty much exact calibration fir the most part through time. Air bleeds etc are pretty much the same.
For some reason about half of the 3259-1's in 1967 have a massive idle feed restriction.
Typical is .069 idle air bleed, .031 idle feed restriction.
On about half of the 67 dated ones you have a .069 idle air bleed and a .040 idle feed restriction.
At first I thought it came from a few over enthusiastic racers.... but I've now found a dozen just like that. Exactly .040, too common to be a fluke.
Any idea how, or why they would be so oversized?

Thanks
Drew

Drew,
I don't know your specific question but by 1967 Ford was selling a 427/428 1-4V "kit" with one of the 'sidewinder' intakes and a "715" vacuum secondary center inlet bowls carburetor. They claimed the combination made the best over all power curve of anything else they offered for the big FE engines. Shelby American had quite a few Holley Custom Shop specials available for their favored customers that somebody like me would never have known about. Most of the customs would look ordinary and get over looked at a used parts swap. Only the 1966-67 center squirters catch almost anybody's attention. I can't help but wonder if what you have data logged was big block specials? (I have a 1967 Shelby Mustang Group II 2-4V induction system, system serial number 4, and the carburetor bodies just have the stock List 2804 and 2805 markings on the air horn.)

OR

Holley® mistakes. People use to buy new carburetors and have them drop shipped to me to sort out assembly line quality issues before they went to the race track. I came across wrong parts, correct parts installed incorrectly, damaged parts, missing parts, and even float pins in side hung bowls that were not staked in place and could drop out if the bowl was tipped one direction.
Dan

PS Quite a few years ago we contacted the owner of the Holley brand and asked about what engineering files we might get access to. The corporate holding company knew nothing they said. We were directed to the Holley Custom Shop. The person there told us he found only a few pages from before the current owner. The few pages were from 1964. We obtained photo copies of them. Some of this was published in the SAAC magazine. The data sheet told exactly what went into the December 1964 production carburetors but that was it. Just in case, the shop was asked again a couple of times over about four years and turned up nothing new. It might not happen in my lifetime but surely some ex-employee took obsolete files home and they still might turn up. (ex SA stuff is turning up all the time)