Had an AFB or Has?



Frank/Rebop

Bristol, In ( by Elkhart) 

While I’ve only seen the AFB carbs on the 1957 Mercury 312’s, I’ve come across both AFB’s and Autolite 4100 carbs on the 1957 Ford 312’s.  All the Mercs I've dealt with had automatic transmissions which could help to explain the AFB only scenario.  My recent 1957 Ford acquisition that had an unmolested 312 was AFB equipped along with the automatic transmission.  This was a Dallas built car.

Lorena, Texas (South of Waco)

I also bought a complete stock 1957 Mercury engine that was equipped with an AFB.
Could it be that AFBs were only used on automatic transmission cars because of their integral dashpots and possibly only in Mercs?


"FREE SAMPLE"

So it sounds like the AFB was the most prevalent 4 barrel on passenger cars. Curious, since ford developed its own with the 4100. I would think there would be a savings not sourcing carbs from independent companies.

Regarding vacuum secondaries, I wasn't sure whether mine were opening until I stuck a loop of duct tape on the diaphragm housing so that it rubbed against the actuator arm, then smeared a film of heavy grease on the arm. The duct tape leaves a track in the grease as the arm is pulled into the diaphragm housing. I can't know if they're always working, but they definitely do at least sometimes!

1954 Crestline Victoria 312 4-bbl, 3-speed overdrive

As to the AFB on the Mercury, the AFB carb and intake that I installed on my otherwise stock 292 in a '58 Ford back in '63-64 came off of a '57 Mercury. Worked great on the '58 after shortening the spring on the secondary diaphragm a bit to get the secondary's to open at the same time the tires stopped spinning on takeoff. Had similar 292's later on with the Holly 4100 or 4150 and didn't notice much difference. Easier to convert the Holly to mechanical secondary's with a screw in the linkage. May not have actually preformed better that way but sure felt better and no doubt that they opened.

Can't comment on which  of the mentioned carbs were used on particular models. However, as noted, the 1957 1st yr Autolite 4100 used on some Fords was altered somewhat for 1958 & later use. It was also original equipment on some early Mustangs. When our modertor, Ted, tested 16 misc carbs on his Mule Y-block, the 1.08 model 4100 was 5th in performance & all but one of the other carbs were bigger in cfm. I'm informed that the one thing to keep in mind on those carbs, is that due to their annular discharge feature, which is unique, they are apparently sensitive to dirt in the fuel. So, if installing one make sure there is a new filter installed with it.  (note, that Summit now sells a modern version of  that annular discharge carb, & apparently John Mummert has had success with it.)   


Paul

In my dealings with the three 4V carbs that were offered on the 1957 312 engines, the only consistency I’ve found is the Holley 4V carb being the only carb offered on the 312 equipped Thunderbirds.  All the 1957 Mercury 312’s I’ve dealt with did have the Carter carbs and all these were automatic transmission equipped but I’ve only dealt with a half a dozen of these cars that were original so I can’t say definitively that the Carter carb was the only one used on that application.  I’ve seen the 1957 Ford 312 equipped cars with both the 4100 and Carter carbs.  Do remember seeing the Holley carb on some of those Ford cars but don't remember if they were original or not.  I don’t have any kind of correlation between the carb style and transmission which may have been a player with which car got which carb.  I have a stack of those 1957 Carter 4V carbs here and not many of the 4100’s so in this part of the country, the Carter carbs came as original equipment on many of the 312’s.

Lorena, Texas (South of Waco)

Sure thing! It's fun studying up on this stuff.

According to Ted's extensive carb test article, the 4100 is about 440 cfm and the AFB is 400. Maybe the slightly smaller size of the AFB gave better low-end torque and throttle response, thus the use with heavy retractables?

Mine is a fairlane 500 town sedan with a/t and I am confident the AFB was the factory install, so at least some sedans got it too.

Maybe the 4100 was used with m/t or o/d transmissions.

1954 Crestline Victoria 312 4-bbl, 3-speed overdrive

Peeeot
You are 100% correct that all 3 carbs were offered in the 1957 Ford engine lineup.
A quick trip to the Service manual confirms those facts.
I am sure about the Retractables getting the AFBs but now I am stumped as to the Autolite installs.
Learn something new every day.
Thanks for the enlightenment.

Oldmics

There is no doubt that all 3 were available in 57 on passenger cars. The 57 4100 is special and unique to that year with a long snout on the accelerator pump that incorporated the overtravel mechanism. Also the nozzle bars have smaller discharge rings than other 4100s and no air gap in the accelerator pump nozzles.

According to this sheet http://www.thecarburetorshop.com/Kford.htm from the carburetor shop, the Holley 4150 was used on thunderbirds and police models, which makes sense if it's the most performance-oriented of the three. There is still no clue about the AFB/4100 applications though.

I bet it's a small percentage of 57 312 passenger cars that retain their original carburetor. I've never seen another y-block using any of these three carburetors but then I have only seen one other 57 312 car in person.

I believe the dual quad cars used the teapot still but the shop manual doesn't cover that or the supercharged version.


1954 Crestline Victoria 312 4-bbl, 3-speed overdrive