Carburetor? - JeepForum.com

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post #1 of 18 Old 05-28-2012, 10:18 PM Thread Starter
qvfd153
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Carburetor?

I just bought an 81' CJ7 with a 304 in it and never owned a vehicle that had a Carburetor before and I have a few questions about the Carb and wanted to see if anyone could help out.


I wanted to see if anyone knows what model # my carb is? It's a Motorcraft. It has two flappers on top, but I believe it's a 2 barrel because I only see two ports.

Also the Throttle positioner solenoid with dashpot has an electrical wire comining out of it and is not connecting to anything What would the reasoning for this? Thanks





81' CJ7 304 V8 4'lift 33" BFG AT
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post #2 of 18 Old 05-28-2012, 10:25 PM
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Doe it look like this Motorcraft 2100? Popular swap.
Attached Thumbnails
Motorcraft2100.jpg  

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post #3 of 18 Old 05-28-2012, 10:28 PM Thread Starter
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Originally Posted by BagusJeep View Post
Doe it look like this Motorcraft 2100? Popular swap.
I don't believe it's the 2100, or even the 2150 because mine has a 2nd small flapper on top and neither of those ones do.

81' CJ7 304 V8 4'lift 33" BFG AT
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post #4 of 18 Old 05-28-2012, 10:58 PM
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What you have is what was called a variable venturi Carburetor. They are not exactly what you would call a decent carb. they were troublesome even when they were new. If it were my Jeep i would get that thing off there ASAP.

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post #5 of 18 Old 05-28-2012, 11:09 PM Thread Starter
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Quote:
Originally Posted by titomars View Post
What you have is what was called a variable venturi Carburetor. They are not exactly what you would call a decent carb. they were troublesome even when they were new. If it were my Jeep i would get that thing off there ASAP.
Thanks, I just discovered it is the 2150.

81' CJ7 304 V8 4'lift 33" BFG AT
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post #6 of 18 Old 05-29-2012, 05:13 AM
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Quote:
Originally Posted by titomars View Post
What you have is what was called a variable venturi Carburetor. They are not exactly what you would call a decent carb. they were troublesome even when they were new. If it were my Jeep i would get that thing off there ASAP.
The third flap is part of the high altitude "kit". The 7700vv variable venturi looks like this:
http://www.grandmarq.net/vb/showthre...uretor-Rebuild
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post #7 of 18 Old 05-29-2012, 08:01 AM
titomars
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Quote:
Originally Posted by jeepdaddy2000 View Post
The third flap is part of the high altitude "kit". The 7700vv variable venturi looks like this:
http://www.grandmarq.net/vb/showthre...uretor-Rebuild
Thanks I stand corrected. It's been many years since i have seen either. My memory is not what it used to be I guess.

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post #8 of 18 Old 05-29-2012, 08:26 AM
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Quote:
Originally Posted by qvfd153 View Post
Thanks, I just discovered it is the 2150.
So by the pictures, my carb is a 2150 as well. Is this a good carb or not???

I am doing a carb job on mine and had to do an alteration to the power valve diaphragm.



cut off the shaft and epoxied on a few washers

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post #9 of 18 Old 06-03-2012, 08:54 PM
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What is the good motorcraft to have? I bought a spare 304 the other day and it came with a 2bbl, that the guy said was the prime carb. What is hot mine has a tag but I didn't read it. What # am I looking for?
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post #10 of 18 Old 06-03-2012, 09:49 PM
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That is the accelerator pump.
It squirts the fuel when you step on the gas.
The nipple you cut off would have just extended through the housing to be pushed by the arm.
The epoxy should be fine since there is no fuel on that side.
The 21xx series carbs are some of the best 2 barrels made.
They're simple, cheap and dependable.

If you wanted performance, you could get a 500CFM or even a 650 CFM two barrel Holley, but with the
constraints in the stock cast iron intake 500cfm would be fine.
The 21xx had two different CFM ratings. I forget what they are now.
One for 289/302 engines, and a larger one for the 351M/W/C and 400 Engines, They even made a 429 with the same
2150 two barrel on it.

I'll be adding a 2150 to my CJ5 258 this week. The Carter BBD is a POS at best.
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post #11 of 18 Old 06-03-2012, 11:51 PM
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I always chuckle when I see someone equate maximum air flow through a carb with performance. Truth is in a Cj with a 304, or even more so a 258, that you will never need a big, big carb. The big carb capacity and low engine speeds means that you will only ever have lower air speeds than the carb was designed for and consequently poor mix and economy.

It does make a difference if you increase air flow but large changes in air flow can only (due to the physical shape of an engine) be due to increase in swept volume or rpm. An appropiately sized Weber etc is a shiny Gucci piece of kit that we all like but costs $$$$$$.

Stick with the BBD, it was a very popular 60s / 70s carb and is corretly sized to the engine. I am not knocking the Motorcraft or the Holley or the Weber designs, all great crabs, but the BBD is unfairly maligned.

My BBD took 3 months to sort, combination of idle tubes and floats that caused it to stop at all traffic lights, but has rumbled on for 5 years without trouble.

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post #12 of 18 Old 06-04-2012, 02:05 AM
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Quote:
Originally Posted by BagusJeep
but the BBD is unfairly maligned.
Only by those that don't understand

Idle tubes......an easy fix and only a problem if it sits more then it's driven.

Throttle bushings wear out......not an easy fix. But they all do at some point. I got a box of 750 holley base plates with worn primary shaft bushings. Ask around and your bound to find someone local that does the rebushing for a reasonable price.
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post #13 of 18 Old 06-04-2012, 05:48 AM
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Quote:
Originally Posted by BagusJeep View Post
.... but the BBD is unfairly maligned.

My BBD took 3 months to sort....
I love irony...

Matt
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post #14 of 18 Old 06-04-2012, 08:20 AM
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Eh, having dealt with both I can't really give the BBD any praise. From an engineering standpoint, it's too complicated and uses unreliable electrical components. I dealt with mine for far too long until I found that the throttle shaft was worn too much (a common problem).
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post #15 of 18 Old 06-04-2012, 02:29 PM
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Define unreliable electrical components.

1 full throttle limit stitch
1 stepper servo motor
1 electric choke
1 sol-vac gizmo controlled by the MCU.

Never had any of these components fail jeep was bought brand new. Throttle shaft bushings last at least 5 to 8 years before it effects off throttle transition. Found a local guy to rebush the plate for 25 dollars. With that done the jeep will rust apart before the carb needs more then freshened up. That's just gaskets and accelerator pump.

The MC is a Holley knock off / clone and simple. But not as tunable without messing with air bleeds to fine tune the idle to main jet transition.
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