1972 carb question?
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Junior User
Joined: Jun 2007
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1972 carb question?
Hey guys, Im rebuilding a 1972 Ford 390 motor. When I bought it, it had a holley 4 barrel carb on top of a holley street dominator single plane intake manifold. I want to put a 2 barrel carb on the motor to try and save on gas. It is a 1975 Ford F100 Ranger XLT 4X4, with a 4 speed transmission. I found a 2barrel carb on ebay. that ad says its for a manual transmission. Below is the ad. How can i determine that the carb is for a manual trans? And does it really matter. Can I use a carb thats made for an auto trans?? Is a 1.21 venturi carb easy on gas? Any info will be helpful as i know nothing on this matter.
Ps, Can anyone direct me to a forum on how to download pics easily on this site.
One 1972 Motorcraft 2 barrel carburetor. Tag number is D2TF-AB A 2F 16 and 2TAB on carb flange. This carburetor is 1.21 venturi 351 CFM manual transmission automatic choke carburetor.
Ps, Can anyone direct me to a forum on how to download pics easily on this site.
One 1972 Motorcraft 2 barrel carburetor. Tag number is D2TF-AB A 2F 16 and 2TAB on carb flange. This carburetor is 1.21 venturi 351 CFM manual transmission automatic choke carburetor.
Hotshot
Joined: Apr 2009
Posts: 14,333
Likes: 247
From: Stanley, VA
Probably the only difference between auto and manual trans. carbs is the provision for hooking up the kick-down linkage for the auto trans.
I would say that since you've got a manual trans. it doesn't make any difference.
I would say that since you've got a manual trans. it doesn't make any difference.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
You can use a carburetor that came on a motor attached to an auto trans with a manual trans no problem. The only time you run into trouble is when you try to go the other way around, as the carburetor used with a manual transmission may not have the kickdown linkage for the auto trans.
My main problem with your idea is that you're replacing a 4-barrel carburetor with a 2-barrel carburetor. For one, you'd have to get an adapter, or change out your manifold. The other problem is that 4-barrels can actually get better gas mileage than a 2-barrel. 2-barrels drive on the two barrels 100% of the time. With a 4-barrel, if you're careful, you can spend most of your time on the primaries. You only open up the secondaries when you punch it. The gas mileage advantage comes from the fact that the primaries on a 4-barrel are typically smaller than the throttle bores of a 2-barrel.
My main problem with your idea is that you're replacing a 4-barrel carburetor with a 2-barrel carburetor. For one, you'd have to get an adapter, or change out your manifold. The other problem is that 4-barrels can actually get better gas mileage than a 2-barrel. 2-barrels drive on the two barrels 100% of the time. With a 4-barrel, if you're careful, you can spend most of your time on the primaries. You only open up the secondaries when you punch it. The gas mileage advantage comes from the fact that the primaries on a 4-barrel are typically smaller than the throttle bores of a 2-barrel.
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Posting Guru
Joined: Jul 2009
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From: Schweinfurt Germany
and fmc is right about the gas mileage I would just take out your carb get it a good cleaning and give it a tune up. Find the holly part number and look it up that will tell you the CFM on it. I am guessing that you will need around 600-650CFM but that is just a guess until i know your high RPM
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Junior User
Joined: Jun 2007
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Ok, I have a 78 ford truck that has a 2 barrel 351w w/an automatic trans. Since its going to be a doner truck for 75 4x4 the front clip and doors. I guess ill use the carb off of it. Is there anything i can look for off the 4barrel and 2 barrel that will tell me which would be easier on gas, given the fact that im not stomping the pedal to the floor at every stop sign?
Mountain Pass
Joined: May 2009
Posts: 232
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From: 40min from Charlotte NPD.
As stated before a 4bbl will have smaller primary bores than a 2bbl. And on that 390, if you are looking for fuel economy and power when you need it I would recommend 600-650 CFM 4bbl w/ vacuum secondaries, look on the top right side of the choke tower for a model number and post it here and we will let you know what you have.
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Junior User
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Ok, I just went outside and looked at the 4barrel Holley carb. The numbers on the top of the carb next to the choke are 7445. The numbers on the side of the carb are 6R-4713B. There is also a set of numbers on the base plate of the carb that read 12R-5395B. There are 2 circles on the carb with numbers inside. The first circle is located on the side of the carb on the secondary tower, it reads 26. The second circle is on the base plate and it reads 6. Those are all the numbers i could identify I hope its enough info to decipher.
Postmaster
Joined: Dec 2008
Posts: 3,940
Likes: 8
From: Southern Oregon Coast
Doesn't look like any of those numbers is the list number.
From the Holley web site:
QUESTION How do I find the "list" number on my carburetor?
ANSWER The list number for most performance and factory 2 and 4 barrel carburetors will be found stamped into the upper right hand corner of the airhorn or sometimes called the choke tower. On the 4150 HP models that do not have a choke tower the list number will be stamped into the mainbody behind the throttle linkage. This number is used to identify the carburetor and also used when needing service parts or renew kits.
Once you've found the list number, you can go here to find the info on it:
http://www.holley.com/data/TechServi...%20Listing.pdf
From the Holley web site:
QUESTION How do I find the "list" number on my carburetor?
ANSWER The list number for most performance and factory 2 and 4 barrel carburetors will be found stamped into the upper right hand corner of the airhorn or sometimes called the choke tower. On the 4150 HP models that do not have a choke tower the list number will be stamped into the mainbody behind the throttle linkage. This number is used to identify the carburetor and also used when needing service parts or renew kits.
Once you've found the list number, you can go here to find the info on it:
http://www.holley.com/data/TechServi...%20Listing.pdf