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Motorcraft 2100 on a stock 350 SBC?

handloader90

handloader90

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I know everyone loves their Q-Jets, but I'm looking into the Motorcraft 2100 2bbl carb as an option for my stock 350. I've heard nothing but great things about it and it's offroad capabilities. My only concern is if the CFM is enough to feed my engine properly. The truck is street driven but not on the highway.

Is anybody running this setup? If so, how do you like it?

Don't know if it helps but there is a SM465/NP205 behind the engine
 
never even heard of it... sounds like a Furd part... :haha:
 
They were used by Ford and AMC years back. I've read many times over that a vehicle will continue to run on it's side or even upside down after a rollover without hesitation hence my interest in one.
 
Whats the CFM rating? Really the only question that needs answered IMO.

If it's a large 2bbl it might be ok, but it's also likely that throttle response will suffer if it's bigger than 250CFM, which is the Q-jets standard primary side.

If overall power isn't a concern for you, a low-flowing carb isn't going to be a concern. There are CFM calculators all over the place, although they are vastly simplified, they will give you an idea of what your motor needs, for whatever your max RPM tends to be.
 
I've ran a few on chevy small blocks--Ford's used them in the 60's and 70's,and a version is still sold by Holley today that is a popular swap for the crap Carter 2 bbl carbs on 4.0 Jeep straight sixes..

They come in 350 and 500 CFM ratings (approx)...so they are equal to or more than adequate for a V8 ,the Rochester 2 bbl's GM used were roughly the same CFM ratings..and they even used some on 455's ,so no worries about being too lean..

The ones I used were on a '72 350 engine,I used a carb adapter that Mr.Gasket makes that allows "any 2 bbl carb to bolt to any 2 bbl manifold"...it was a bit of a chore finding the right gaskets to block off all potential vacuum leaks,but once I got past that,and added a hand choke,I liked the Motorcraft carb better than the Rochester...the accelerator pump diaphram can be replaced easily from outside by removing 4 screws,and the gas mileage seemed a tad better too...I never off roaded my trucks to any extreme,so I cant say if they are as flood resistant as they have been claimed to be or not..

Also forgot to add that these carbs were popular on dirt track cars,the rules forbid 4 bbl carbs,so they made an adapter plate to mount the 2 bbl over the existing manifold's 4 bbl openings,some of which can be "slid back" on slotted holes to improve air-fuel mixing...Jegs still sells those adapters..
 
2 Barrel and 4 barrel carb CFM's are rated differently, IIRC the 2 barrels are measured at a 3" hg pressure drop and 4 barrels at a 1.5" hg pressure drop. So the 2 barrels are even smaller than the numbers would make them appear.

I would take a Q-jet over a Motorcraft any day.
 
The big advantage of a Q-jet is that most of the time it is on the small primaries, giving two-barrel fuel economy, while retaining the option to open the big secondaries on demand if you romp on it. It's the best of both worlds as far as a carburetor goes. When it comes to offroad applications, the Q-jet is also one of the better carburetors out there when it comes to running at extreme angles. IMO, there isn't much advantage to running a Motorcraft carb.

If you're really looking for uninterrupted power "upside down", fuel injection is really the only way to go there. Since your setup is stock, you can piece one together pretty cheaply.
 
diesel4me said:
I've ran a few on chevy small blocks--Ford's used them in the 60's and 70's,and a version is still sold by Holley today that is a popular swap for the crap Carter 2 bbl carbs on 4.0 Jeep straight sixes..

They come in 350 and 500 CFM ratings (approx)...so they are equal to or more than adequate for a V8 ,the Rochester 2 bbl's GM used were roughly the same CFM ratings..and they even used some on 455's ,so no worries about being too lean..

The ones I used were on a '72 350 engine,I used a carb adapter that Mr.Gasket makes that allows "any 2 bbl carb to bolt to any 2 bbl manifold"...it was a bit of a chore finding the right gaskets to block off all potential vacuum leaks,but once I got past that,and added a hand choke,I liked the Motorcraft carb better than the Rochester...the accelerator pump diaphram can be replaced easily from outside by removing 4 screws,and the gas mileage seemed a tad better too...I never off roaded my trucks to any extreme,so I cant say if they are as flood resistant as they have been claimed to be or not..

Also forgot to add that these carbs were popular on dirt track cars,the rules forbid 4 bbl carbs,so they made an adapter plate to mount the 2 bbl over the existing manifold's 4 bbl openings,some of which can be "slid back" on slotted holes to improve air-fuel mixing...Jegs still sells those adapters..
Click to expand...

This is the exact info I was looking for! Thanks!
 
Thanks for all of the info guys. I've had a GM Q-Jet sitting in my garage for the past year or so. I bought it for $20 from a guy that took it off of his El Camino.

It's an electric choke model and is one or two throttle linkage parts that are missing and in my eyes needs a rebuild. It is very clean especially compared to the BOP one that I had picked up from Craigslist prior to the one I currently have.

I'll be rebuilding the Q-Jet mid 2015 and will also be picking up a Motorcraft 2100 and 2150 (If you have one or two that you're willing to sell please message me).

The plan is to install both carbs on my engine and put it on the engine stand, make all proper adjustments and adjust the engine stand to different angles to mimic off-camber situations, testing throttle and such at the same time.

Whichever one performs the best will be the one staying on the engine.

My engine has a few alterations, it is a low mile rebuild (give or take 6k - 8k miles) I assume it has been bored, no more than .30 over and has a slightly larger cam installed. I said it was a stock engine because it is very mildly built.

I'm currently not interested in TBI or EFI, I'm really in love with carburetors, ease of installation, ease of operation and ease of trouble shooting.
 
handloader90 said:
ease of operation .
Click to expand...



:haha: apparently you don't drive too many EFI's...

EFI does EVERYTHING it can to stay running, carbs do EVERYTHING they can to stall... :deal:

I was a diehard carb guy, f*ck that sh*t... :haha: pump twice, hope the choke works right, etc, etc...

run the carb, but don't be afraid of EFI, TBI is stoopid simple..
 
When I do go fuel injection it will be in the form of an LS engine. That may be a ways off for me. I'm still learning my way around wiring, once I have some more electrical experience under my belt I'll definitely be looking at an LS.

I'm self taught with occasional help from knowledgeable friends and the great members of this board, I refuse to take my truck to a shop for ANYTHING. I feel that it takes away from learning, troubleshooting and proper maintenance and also degrades the "Built Not Bought" motto that we all love to claim!
 
It also helps prevent your butt from being reamed at shops that like guessing at whats really wrong with the vehicle,and just throw parts at it--or just plain wants too much $$$$ for doing some repairs you can handle yourself..

I get frustrated lately,I hate knowing how to fix things,and now have to pay someone else to do most of the work I used to be able to handle myself due to physical limitations...it's one thing to get taken advantage of by a shop if your mechanically clueless--but when you KNOW its not that "bad" a job ,having done it before yourself--and you have to pay top dollar to have it done now,it really irks you..
 
I've seen several rigs in our off-road club running the 2100 series carbs. These were on a stock 302, built 351, and a stock 460 and all seemed adequate in regards to flowing enough for higher RPM stuff. Throttle response was really good and they would run at any angle. Maybe the size limited the upper RPM some but enough to be obvious. The guy with the stock 460 later installed a built version (not wild but healthy at around 350 HP and 500 Ft-Lb) and it did hold it back some in the upper ranges. He eventually went to a Q-jet and than propane.
 
I think the biggest 2v ford carb was close to 400cfm. Not sure how it was rated, but removing the ford carb for a holley 4412 (500cfm 2v) was a big power improvement.

The motorcraft carb is good, but I would never put it in the place of a qjet.
 
You can find 2 barrel vs/ 4 barrel info all over but here's a decent source. The OE V8 2 barrels will choke pretty much anything more than a 70's/80's smog era small block.

If power doesn't matter and you just want the thing to run at any angle, the Motorcrafts do well. Having been around both, they seem to be about the same offroad. However, I believe the Q-jet is better at every other function and came on practically every Chevy V8 for ~30 years where the Motorcraft was pretty much Ford only. So I don't really see reason to swap.

And for what it's worth, neither will run anywhere close to "upside down". They both reach their limits well within the capabilities of a full bodied truck, albeit at the "hardcore" end of the spectrum.
 
I have had friends run motor crafts quite a bit. Nice carb good on angles but not on severe angles. Runs similar angles to the quadrajet.

They choke a decent motor down big time. Took me a while but I convinced a buddy to put a quadrajet on his stroker 347. Nice motor. It blew his mind how much that 2 barrel had been giving up. He was also convinced it wouldn't run at angles as good as his motorcraft. Suffice it to say it did.

I ran a quadrajet for years kind of like you. I don't need no steenkin fuel injection. We'll actually I did. I just didn't realize it till I had it.
 
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