Home Forums Gear Hunting Trucks and Four-Wheel Drives Offroad and Truck carburetors:

Recently, I've seen the popularity of these expensive efi kits increase. Holley sniper and fi tech, they both use cheap Chinese sensors and are not as reliable as some folks think.

If I was forced to spend big bucks on fuel injection for an old 4x4, I'd go howell efi, that uses all OEM GM throttlebody injection components. It's a reliable system.

BUT, the TBI is literally an electric carburetor. I've rebuilt a tbi on a k5 blazer last year. The barrel injectors just dribble fuel onto the fkn throttle plates, at less than 9 psi. Common man! You don't really see appreciable fuel "atomization" untill the engine is above about 1/3 throttle, where the fuel pressure might be around 12 psi, and the manifold vacuum demands more fuel:


I would never put a fkn weber on an offroad rig. Nor would marketing slogans like "truck avenger" or "avs2 offroad" do anything well. A holley will never be an offroad carb. A CARter based edelbrock will never be an offroad carb. These are street carbs cobbled together with bandaids and cheesy marketing.

For the price, none of new carbs mentioned will do what a motorcraft 2100 has been doing for 60 years or more:
Amazing offroad performance. They're already good as is, and can literally be turned into an atv carb with some Brennans Garage goodies.

Ford bronco guys know them well. Jeep guys know them well. But because of these silly brand loyalties, chevy guys don't know sht about them. Nor do toyota guys with their stupid weber carb kits on 22r's or 2f's or smog-laden garbage aisin carbs on landcruisers and older toyota trucks.

A few positives:
Excellent cold starts, even in 30-40 below zero
Reman carbs are cheap, got mine from rock auto for about $250.
Can literally re-jet with the carb on the 4x4. The bowl is like a little tub. Nowhere to spill fuel.
Jets are down in the bottom of the bowl, no rough bouncing will stumble the carb.
The 2100 uses annular boosters where 12 tiny holes atomize the fuel. So low-end clutching with thousands of lbs of firewood, you never stall out. Much better than brass down-draft tubes that just dump a stream of fuel into the manifold.
Because of the baffle box kits and vent modifications, you can run some very wild hill climbs or descents, and not flood out carb or stall.
Good Pic of the venturi cluster with annular boosters:




Negatives: They tend to run rich at 3/4-wide open throttle. You might see this when using a wide ratio air/fuel guage to tune carb. You can thread the power valve orfices that feed the 2 barrels to accept universal jets, or just deal with sht going slightly rich. It's good protection to go slightly rich at full throttle. Detonation is a btch!

Funny, my quadrajet on a 327 chevy v8 goes lean with aggressive 3/4-full throttle(quadra-bog). Literally had to buy a "cliff Ruggles quadrajet" book to understand how to adjust those massive secondaries. So I'll take full thottle "rich" every time. I still don't fully understand the quadrajet and have 3 different books on this series of carb. Nowhere near as simple as the motorcraft 2100.




Here's the size carbs they came in:

0.98 = 190 CFM
1.01 = 240 CFM
1.02 = 245 CFM
1.08 = 287 CFM
1.14 = 300 CFM
1.21 = 351 CFM
1.23 = 356 CFM
1.33 = 424 CFM

4 cylinder jeep or toyota or small v6's: the smaller cfm carbs for sure.

Mild jeep or landcruiser inline 6's, the mid-range carbs would be best.

Big inline 6's like the 300 Ford or 292 chevy or smaller 300 cubic inch v8's, 1.14-1.21

Larger small block v8's like the chevy 350, ford 351 or dodge or amc 360: 1.21 or 1.23

I would not run a 1.33 on anything but a gigantic 3/4 ton or 1 ton wood truck, hay truck or plow truck with a big block V8.

Good offroad mods:


https://brennans-garage.com/products/autolite-motorcraft-2100-2150-carburetor-fuel-bowl-kit

Edelbrock Pro Flo 4 is what I chose for my Mustang. Sequential multiport. The ECU is mounted inside the cab. To say I am pleased is an understatement.

Back in my Jeeping days we ran quadrajets, they seemed the least prone to flooding out on steep inclines.

Good post!

I only have 3 carbs on off-road vehicles, and they are on vehicles that only have 2 wheels each.

Carbs are still a viable choice. I've rebuilt dozens of small engine carbs. Chainsaws, atv's outboards, snowmobiles, etc.

If you can check a primer of a handloadn you can check the color of a spark plug. It's really sad, the lack of knowledge with a lotta young guys, over carburetors.

I have a tekei carb that has such an effective choke circuit, that the snowmobile will start at 50 below zero without a primer bulb!

Many EFI snowmobiles won't.

A Honda carb on my gx 690, gives better than 10 mpg, pushing a bull moose UP the Yukon River.

Trucks are no different. If carb be tuned properly, they start well in the cold and give acceptable fuel economy.

Nailed it.

Good post. People ask frequently if I have a four barrel carb on my 73 Bronco..."Nope, no way, stock Motorcraft."