2100 vs 2150 and 1.21 vs 1.08

[HOT RAM]

I let the Bronco sit too long and plan to rebuild the carburetor.I currently have a stock 94 5.0 engine converted to 2 bbl. and am using a 2150 with the 1.21 venturi size.It runs well and starts easily even in winter with no choke of any kind.My Bronco is 74.

My question is would a 1.08 venturi size give me better throttle response ? Better mileage ? More or less power ? And would a 2100 run as smooth as the 2150 ?

 

[HOT RAM]

Anybody ??

 

[Broncobowsher]

No garantees. The condition and tune of the carb will be a bigger factor in how they run.

Properly tuned and operating the small carb should give better throttle response then a larger venturi. At the expense of power as well. Fuel economy is simply a factor of how it is tuned. A correct air fuel mix is correct no matter how it is delivered. A smaller carb can give better economy, but not related to better mixing. Simply it restricts the air, and less air means less fuel needed as well, again all at the expense of power potential.

So there is no guarantees. A larger properly tuned carb can provide better drivability and economy than a small poorly tuned carb. And by tuned I mean everything related to the tune, not just idle mix and jet sizes. I mean air bleeds and power valves as well. Throttle shaft wear is another factor. Some of this stuff isn't really that tunable at home or even at a carb shop.

 

[broncnaz]

Usually a smaller carb will give better throttle response than the larger carb. Also a smaller carb tends to be easier to tune. While the 2150 is a slightly better carb for economy purposes it came about basically because the 2100 needed a update due to the fuel shortage and emissions standards of the time.

As was said either can work fine if properly tuned. but in most cases the smaller carb will be better. heavy vehicle, small engine and lower speeds the small carb wins. Where the bigger carb will still run the low end driveability can suffer a little but you will have more topend.
Overall Id probably go with the 1.08 of course you can always swap the 1.21 on and see what the differances are for yourself.

 

[jckkys]

The '77s came with a 1.08" venturi 2150. So you can have both. The 289 in my '68 had a 1.08 version of the 2100 and it ran better than either my '74 or my '77 302s with better mileage. That may be because the cams were "supposedly" retarded 4 degrees in '72. I can see no advantage in the 2150 over the 2100. The tapered rods decrease air flow to the main air bleed as the throttle is opened, yielding a richer mixture. Ford dropped this feature from 2150s in the early '80s. The vacuum diaphragm choke pull off works but so did the piston type. They just have to be kept clean.

 

[HOT RAM]

Thanks !!!!

 

[HOT RAM]

I have three mix and match ,two 2100's and the 2150 I have been using.The 2150 works but seems too rich (has the 1.2? venturis) The 2100s are the 1.08.Hope the choke works on one of them.No choke on the 2150 and takes a lot of pumping to start in the winter.

 

[vintage bronco]

In my opinion I would use a 2100 over the 2150 much simpler carb and I do not believe all the hype on the 2150 I can get a 2100 to run super and mpg better than the 2150 again my opinion I would never pick the 2150 over a 2100

 

[HOT RAM]

In my opinion I would use a 2100 over the 2150 much simpler carb and I do not believe all the hype on the 2150 I can get a 2100 to run super and mpg better than the 2150 again my opinion I would never pick the 2150 over a 2100

I'm thinking the same.The 2100 was on it when I was getting 18+ and now I'm getting 15-16 with the 2150.The 2100 was the 1.08 and the 2150 is a 1.23 .

I never go over 4000 ft in elevation anyway,so the simpler should be better.

 

[broncnaz]

Smaller is better unless you actually need the airflow.

 

[HOT RAM]

Smaller is better unless you actually need the airflow.

It is just a stock 94 5.0 with headers.With 3 body lift,3 1/2 suspension lift,and running 37 bias-ply tires,I don't need to go fast.;D

Mainly want better throttle response and gas mileage ,it seems to be running rich to me (which might explain not needing a choke ?)

 

[HOT RAM]

Any recommendation on jet size ?

I think the one card has 46,one has 50 and not sure on the third.

 

[jckkys]

Individual carburetor part numbers are calibrated in several ways. Different air bleed sizes, different emulsion tubes, etc. all effect the main jet size selection. No direct correlation between between venturi-bore size and jet size can be made. Use the jet that a specific carb was built with, unless your engine demonstrates a need for richer or leaner jetting.

 

[HOT RAM]

Thanks ! there seem to be hundreds or maybe thousands of variations of the 2100/2150 carbs.It can be quite confusing.

hoping the the one with the 48 jets and 1.08 venturis works for me.Especially since it has a choke on it.But I can always make that a manual choke.

I just hate extras,some seem so bare and clean and others have all sorts of things added in and on.

 

[HOT RAM]

So,I took what I had available and cleaned and rebuilt a 2100.It was filthy, with rust in the bowl,oil and varnish all over the outside,rusty linkages.

I removed some pieces i don't plan to use,set the float level and set the idle adjustment screw and the air bleeds to what i thought would be a good starting point.Re-installed it,hooked everything up,cranked the engine while pumping throttle.Fired right up.After a few minutes adjusting it purrs like a kitten.From the sound, it definitely has higher velocity than the 1.24 venturi 2150 carb i was running.

Hope to get my mileage back up to 18mpg and have better throttle response .i will buy a manual choke conversion for it later this week.

Thanks for all the advice !!!!!!!!!

 

[broncnaz]

37in tires and 18mpg keep dreaming, You should get better throttle response.

 

[HOT RAM]

37in tires and 18mpg keep dreaming, You should get better throttle response.

Got an honest calculated 18 mpg on 35's on I-81 at 70 mph
that was with a 2100

Admittedly,I was really trying to get high numbers so I was thinking SMOOTH the whole drive (80 mile drive)

 

[HOT RAM]

Does anyone have any recommendations on power valves ?
Been reading about tuning the throttle response by using different power valves.

This is something I had never heard of before,but I am always ready to learn.

My Bronco is used mostly for trail use but I drive it to the trails and back and sometimes just drive it around for the fun of it.Not a really "serious" crawler,but hate stalling out when doing technical climbing.

As always,open to thoughts,opinions,advice ;D