This is the third post for my recently acquired 1974 F100, 2WD… I appreciate the help and advice I’ve received on the forum as I sort out the truck. The engine is a 1971 351W (truck originally had a 302) with manual 3 speed.

I don’t know where the carb came from, but it seems to match the Motorcraft 2100 rebuild kit I purchased. Notice all the gunk in the fuel bowl… now I know why the truck didn’t run very well.

Questions:
Is the 2100 an appropriate carb for the 351 W?

As seen in the picture, there is some sort of brown adhesive over the venturi cluster. What is it for, and should I remove it, or leave it alone? I’m assuming that I shouldn’t soak that in carb cleaner when I disassemble the carb?

What is the linkage that I’m touching with my finger? It was just flopping around. (I’m wondering if the return spring should have been attached to this extra linkage, so that it doesn’t flop around?)

Does the pump rod appear to be oddly bent, or is that normal? I’m wondering if someone tried to bend it for extra adjustment?

The jets are # 60. Is that a reasonable size for the stock engine?

Finally, the choke needs a hot air supply that is missing. It was suggested that I convert it to an electronic actuator. Is that the best way to go?

Thanks

 

The 2100 is an excellent carburetor, some say one of the best designs ever with their annular discharge cluster. They came in several different sizes and configurations for a bunch of different cars and trucks depending on engine displacement, weight, gearing, transmission etc.

The Shop Manual specifies the carburetor venturi size and booster cluster, jets, power valve, and basic adjustment settings that are correct for the engine that came with your truck. There's way too many variables to say after all these years if #60 jets are correct. Is that even the carb that came with your truck? What elevation are you at? They are probably "close" but then, how do the plugs look? Also keep in mind it's common for someone to drill jets, so those 60s might not even really be 60s. Check with a numbered drill bit shank.

The venturi size is stamped on the drivers side of the carb body, in a circle. They had lots of different sizes, from 1.02", 1.08", 1.12", 1.21" etc. Truth be told any of them will work fine if setup right. The main thing a larger carburetor does, is provide a higher top end speed and power. You won't notice it just driving around town unless it runs worse, which it might. A carb and intake together is a tuned unit for the application and engine will run best at a certain speed and RPM. Depends on what you want from your truck. If you want to drag race and setup for that, hot cam and the rest of it, it will run really great when floored and at 4000+, but it may not hardly even idle.

By installing the stock carb in my slick and tuning it right the fuel mileage more than doubled and it runs better than ever. Tune for what you really want, not what you think you want. Remember an engine is basically an air pump, a bigger carb is usually wasted $$ and gas, without the right intake and free flowing exhaust system among other things, and it won't run very well except when wound out. For a street driver this is usually a mistake. The proper size carb will have enough air velocity through it at low RPM to atomize the fuel and air mixture. In trucks this is important when hauling heavy loads for low speed torque and smooth running from a stop.

Not sure what's going on with the cluster. There should be two discs that are staked. The whole thing including the booster cluster especially, should be soaked in a good carb cleaner and the passages blown out with shop air. It's important that everything is clear, all the tiny orifice. Use new needle and seat. Download the Ford carburetor manuals from one of the carb sites. They are pretty easy to setup, but don't skip anything. Make sure the fuel pump is putting out good pressure and volume too. Take your time, do it right and it will run like a new engine when yer done!

 

I'll try to answer your questions in the order you have them listed.

Is the 2100 an appropriate carb for the 351 W?

Most all 351W engines from 1970 on were equipped with a 2100 or a 2150 carb

As seen in the picture, there is some sort of brown adhesive over the venturi cluster. What is it for, and should I remove it, or leave it alone? I’m assuming that I shouldn’t soak that in carb cleaner when I disassemble the carb?

The material appears to be an epoxy of some sort. Not an uncommon fix to seal the "caps" at the top of the venture cluster after removal of the caps for cleaning.

What is the linkage that I’m touching with my finger? It was just flopping around. (I’m wondering if the return spring should have been attached to this extra linkage, so that it doesn’t flop around?)

The linkage is for the downshift linkage for an auto trans. From the factory there was a small spring that connected to a bracket to keep tension on the linkage. The bracket mounted to the carb baseplate, using the holes just to the rear of the forward carb mounting hole.


Does the pump rod appear to be oddly bent, or is that normal? I’m wondering if someone tried to bend it for extra adjustment?

The rod does appear bent. Bending this rod won't allow for any extra adjustment. As long as the accelerator pump linkage moves freely and doesn't hit anything you should be good. I would attempt to straighten the rod where the clip attaches.

The jets are # 60. Is that a reasonable size for the stock engine?

Lots of variables on jetting. A # 60 doesn't seem out of line for a 351, though. Would be best to ID the carb and confirm what jets Ford originally installed. Checking spark plug color is always advised, as well.

Finally, the choke needs a hot air supply that is missing. It was suggested that I convert it to an electronic actuator. Is that the best way to go?

Personal preference here. The original exhaust manifold would have provisions for a hot air tube and supply tube. Choke stove kits are available if you happen to have headers. If you choose to run a Motocraft electric choke on your carb you can power it off the "S" terminal of the alternator. Should you change to a Holley or Edelbrock carb with electric choke you will need to power those from a dedicated 12 volt ignition on source.

Hope this helps.

 

Thanks Tedster and Roger. This is very helpful. Any opinions on whether the epoxy on the Venturi Cluster is necessary? Should I leave it there ... maybe I'm over-thinking, but am concerned that it could come loose and cause damage. BTW, the venturi size is 1.23, which apparently translates to 356CFM. Thanks again.

 

If it were me I'd want to remove that and clean everything up inside, can buy new caps from carb vendors and restake them, have seen them for sale at Mike's Carburetors iirc. There really is a wealth of parts and information on these carbs, not as spiffy as fuel injection but with a little tuning it will get ya pretty close.

I think these are the guys here - $0.29 ea., so shouldn't break the bank. Be sure to ask before ordering though.

http://www.carburetor-parts.com/Alum...16_p_2413.html

 

The epoxy is there to seal and secure the original caps, as the caps had been unstaked and removed at some point, most likely to thoroughly clean the booster assembly.

If the epoxy appears loose or starting to peel I would remove it and replace with something similar. JB Weld is a viable choice.

 

Roger and Tedster, thanks again. Mike's Carburetor is where I got the rebuild kit.

 

http://c805745.r45.cf2.rackcdn.com/m...100_manual.pdf

It is important, like the others have stated that you check the small ports to be sure they are clear.

If the engine was backfiring, those events shove small particles up the Venturi Ports and the Discharge Shooter Ports for the accelerator pump.

Also, the power/enrichment valve vacuum port path should be checked along with the accelerator pump path.

 

351W (6 valve cover bolts per side): 1969/89 misc FoMoCo Passenger Cars; 1975/97 Econoline; 1981/96 F150/350 & Bronco; 1997 F250 H/D & F350.

2100 series 2V: 1962/74 Ford/Merc Passenger Cars/F100/350; 1966/74 Bronco; 1969/74 Econoline.

Carb kit is the same for all 1962/74 2100 series 2V (D4AZ-9A586-A [replaced C2AZ-9A586-B] Motorcraft CT-499-D), but...

Some 1970/74 2100's have a choke pull-off diaphragm (D0AZ-9J549-C / Motorcraft CK-1283) mounted on the top of the air horn, does not come in the kit.

There are also myriad different jets, but were only sold by themselves, do not come in the kit.

Since the OP's 1974 F100 has a 1971 351W, it could only have come from a car.

 

Personal preference here, but I went with a manual choke. Cost about $15 from any parts store, they're universal, and they install fast. Gives you complete control over the choke. Electric gave me 2 different problems that I got sick of after replacing it twice.

 

^ same here, not a big fan of electrics, they just don't work right year-around. They start out all the way on when the motor's cold, and open at pretty much the same rate whether it's -40 or 110 degrees out. I know they say that they account for engine heat, but not enough, in my opinion. Thermal Chokes are the only auto ones that really work well.

 

Pretty tough to improve on the simplicity of manual choke. Nothing much to break down, less to go wrong. Useful for troubleshooting at times.