TheAMCForum.com Homepage
Forum Home Forum Home > The Garage > AMC 6 Cylinder Engine Repair and Modifications
  New Posts New Posts RSS Feed - 2 Barrel Carbs
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Click for TheAMCForum Rules / Click for PDF version of Forum Rules
Your donations help keep this valuable resource free and growing. Thank you.

2 Barrel Carbs

 Post Reply Post Reply Page  <12
Author
Message
232jav3sp View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Jan/09/2013
Location: Texas
Status: Offline
Points: 2451
Post Options Post Options   Thanks (0) Thanks(0)   Quote 232jav3sp Quote  Post ReplyReply Direct Link To This Post Posted: Jul/27/2017 at 5:56pm
I have a stock 2bbl Motorcraft from a 304 that I would like to sell.  I can rebuild it as well.
Back to Top
Mr. Ed View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar

Joined: Nov/12/2010
Location: Sewell, NJ
Status: Offline
Points: 4916
Post Options Post Options   Thanks (0) Thanks(0)   Quote Mr. Ed Quote  Post ReplyReply Direct Link To This Post Posted: Jul/28/2017 at 11:26am
I have the rebuilt 2100 that came off of my '77 304, automatic car. I also bought the adapter to go on a 6 cylinder manifold but it leaked vacuum so the whole kit and kaboodle is in a box ready to ship. Interested?



Later!
Mr. Ed
2014 Jeep Grand Cherokee Laredo "Gwendolyn."
1978 Concord Sport coupe "Mr. Black".
1982 Concord wagon. The Admiral. FOR SALE!
1976 Sportabout X, 304, auto, air. The Bronze Goddess

Back to Top
firefly View Drop Down
AMC Nut
AMC Nut
Avatar

Joined: Dec/23/2008
Location: wi.
Status: Offline
Points: 355
Post Options Post Options   Thanks (0) Thanks(0)   Quote firefly Quote  Post ReplyReply Direct Link To This Post Posted: Aug/09/2017 at 10:14am
I have a mc 2100 with the 123 Venturi. It's 356cfm. I rebuilt it and never used it. It came on a 360. This would work well on you engine! $125 shipped 715-827-1777

Edited by firefly - Aug/09/2017 at 10:17am
Back to Top
mikouj View Drop Down
AMC Apprentice
AMC Apprentice
Avatar

Joined: May/19/2013
Location: wisconsin
Status: Offline
Points: 33
Post Options Post Options   Thanks (0) Thanks(0)   Quote mikouj Quote  Post ReplyReply Direct Link To This Post Posted: Oct/22/2017 at 6:42am
Not a fan of Carter carbs, so I scrapped the 1-V setup from my 232 replacing it with the 81-up aluminum intake, an MC2100 carb, and an adapter that I built to marry the 2 together.  It ran fine.  The consistent mileage at 18.8 I consider poor, however.  I'm comparing this to the 27 mpg my supercharged Honda Prelude delivers on my particular mix of mostly to and from the nearest town 12 miles away.  The Honda has an engine about 1/2 the displacement but 250% of the 232's hp. Should be able to better than 18.8 right?  I had some other issues I was trying to sort out so I bought a WIDE BAND O2 sensor and hooked it up.  I was shocked and stupified by what I saw.  At idle, warmed and adjusted to lean best, the air/fuel ratio was about 11:1.  As rpms increase past about 1500 the AF gradually leans to about 14 - 14.5.  Lift your right foot completely and the AF pegs the needle at full rich (sensor readout is 10 - 18 in increments of .1).  So, putting thru town in 4th gear at 1200 - 1400 rpm the AF was always in the 12- 13 range, consequently, poor mileage.

These are characteristics of carburetion in general not specific to the MC2100.  Most motorheads accept the chemically correct mixture of gasoline and air to be 14.7:1.  True for pump gas but be aware that stoichmetric for 2,2,4 trimethylpentane (also known as iso-octane and natural gasoline) is 15.1:1.

I figured I could get better mileage if I leaned out both the idle and main circuits without sacrificing performance (the power valve supplies the extra fuel when your foot is in it).  I played with the float level, replaced the .049 jets with .047, and turned in the idle mixture screws.  Mileage improved, the cruising (2000 rpm+) AF went to 15-16, but low speed AF was still in the 12-13 range.  I drilled out the .027 idle air bleeds (on the back side of the removable booster venturi first to .028 then .029; that did lean out the low speed AF to 13-14 from 12-13.  I later went back to the .049 jets.  Now I get 22.4 mpg tank after tank.

I have also used the MC2150.  It uses variable idle air bleeds to achieve a more constant AF ratio across a wide range of speeds (it doesn't actually).

To your question then,  The MC2100 is easy to use, adapts easily, and can be tuned for better performance.  What I don't like is the variability of AF from day to day.  For no reason I can discern one days town run will give an AF of 14 - 14.5, but the next days' will operate at 15.5 - 16.

Finally, improving on factory calibration of any make of carburetor without using a WIDE BAND O2 sensor is quite difficult.
Back to Top
farna View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar
Moderator Lost Dealership Project

Joined: Jul/08/2007
Location: South Carolina
Status: Offline
Points: 19611
Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Oct/22/2017 at 10:33am
mikouj, you're comparing 1960s tech with 1990s tech. SO MUCH happened in 0s and later! The AMC 232 is a great engine, and "fathered" the 4.0L (which is for all practical purposes the same engine with EFI added, a little better head and a little more displacement, but darn near the same). Even the 4.0L with 244 inches and EFI produced "only" 190-195 hp. Lot lower rpm than the Honda, and much better torque curve, as well as producing usable torque at a much lower rpm than the Honda... so apples to oranges as far as design (and design goals).

Carbs are subject to current weather conditions. You're obviously used to EFI which can easily tune the engine for current conditions, keeping the AF ratio just about right all the time. Carbs are "just good enough" -- they fluctuate from day to day as you noted. Lots of variables -- weather, fuel, etc. The 2150's variable air bleeds were an effort to make the AF ratio more consistent. Probably does do it a bit better than a 2100, but not enough to be worth it today. At the time they were on the verge of going all EFI, and "just a little better" helped with emissions.

I'd go with one of the smaller MC2100 carbs on a six -- no more than 1.08 unless you're building a motor for high rpm running -- and don't expect it to run well/efficiently at low speeds. 500 cfm is about the most a 258 will handle, but even then it needs to be a high perf engine and won't run real efficiently at mid and low speeds (under 2500 or so rpm). The 350 Holley is the better for a street engine, but the Weber 38 is a good choice also.

Webers can take some time to properly tune, but worth the effort and once tuned will be one of the most efficient carbs available. The smaller 32/36 is a great carb for a street 232 or 258. Good economy and power due to the two stage design. The 38/38 is synchronous -- both barrels act together -- just like most other 2V carbs (MC 2100/2150, and Holleys).  The 32/36 is a bit better for power than the old stock BBD or WCD but still delivers fuel economy.

The Holley 5200 is a Weber copy (licensed by Holley). It's a DGV progessive linkage like the 32/36, but smaller. 32/36 is about 320 cfm. 79-82 Ford four cylinders used a 23/27 235 cfm model. That would be a decent carb for a 232/258. The factory BBD is rated around 195-200 cfm. Just the progressive linkage would be worth a bit better throttle response at low speed and a bit better economy, though 35 cfm won't give much more power (if any more) at high rpm. Would still be a good replacement for an aging BBD.

Here is a good primer on Weber carbs. If you want a new carb I'd go with a 32/36 or 38/38 Weber.
http://datsun1200.com/modules/mediawiki/index.php?title=Weber_32/36_Carburetor
Frank Swygert
Back to Top
vinny View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum


Joined: Jan/05/2012
Location: Calgary
Status: Offline
Points: 2837
Post Options Post Options   Thanks (0) Thanks(0)   Quote vinny Quote  Post ReplyReply Direct Link To This Post Posted: Oct/22/2017 at 11:10am
Probably the Motorcraft is what was on a 289 in a 67 Fairlane I owned? I had no problems I can remember with that carb. Maybe the same carb on a 65 Mercury P/U with a 352? No problems with that one either. Maybe that's why I know nothing about them.
Back to Top
carnuck View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Mar/31/2010
Location: Seattle
Status: Offline
Points: 3942
Post Options Post Options   Thanks (0) Thanks(0)   Quote carnuck Quote  Post ReplyReply Direct Link To This Post Posted: Oct/22/2017 at 12:15pm
If you are running an automatic then economy sucked.
Back to Top
amcenthusiast View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Jul/02/2012
Location: SW Atlanta GA
Status: Offline
Points: 1778
Post Options Post Options   Thanks (0) Thanks(0)   Quote amcenthusiast Quote  Post ReplyReply Direct Link To This Post Posted: Oct/22/2017 at 2:07pm
IMO this whole topic is related to carb problems with the E-10 gasohol.

All the old school carbs that used rubber diaphragms (originally made for 'real' gas) are now giving many people trouble -especially those on older cars that only get run occasionally.

This is because E-10 evaporates fast and speeds up the life cycle of the old nitrile 'Buna N' rubber parts; after so many cycles of going dry and refilling the carb they go bad and begin to seep fuel into engine doing more harm than good to say the least. (how's your old lawnmower doing?)

Y'all need to consider swapping in Rochester 'Dual Jet' two barrel (not the '2G' those are heavy, less intelligent carbs) or earlier AMC type Carter WCD two barrel units because neither of those have the now-obsolete trouble prone rubber diaphragm circuitry like MC 2100/2150 or Holley modular two barrels. Get with the EPA E-10 gasohol program & forget banging your head on the wall with already outdated less E-10 tolerant MC 2100/2150 swaps.

more tuning parts for Rochester Dual Jet two barrel:
 
https://quadrajetparts.com/rochester-dualjet-210-c-181.html

as compared to Carter:

https://quadrajetparts.com/carter-wcd-wgd-wgd-2bbl-carburetor-parts-c-299_300.html

can't teach an old dog new tricks?... the E-10 gasohol doesn't care/gotta learn anyway TS
443 XRV8 Gremlin YouTube video: https://www.youtube.com/watch?reload=9&v=2DmFOKRuzUc
XRV8 Race Parts website: http://amcramblermarlin.1colony.com/
Back to Top
Nodak68 View Drop Down
AMC Apprentice
AMC Apprentice
Avatar

Joined: May/08/2016
Location: Boston, MA
Status: Offline
Points: 103
Post Options Post Options   Thanks (0) Thanks(0)   Quote Nodak68 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/22/2017 at 2:29pm
I have a MC 2150, electric choke, and '84 aluminum intake/cast iron exhaust on my '68 232 Rogue.  This is a great carb - we had them in our 70's Ford pickups when I was growing up on a farm in North Dakota where is was COLD in the winter, and prior to EFI you couldn't beat them for reliable cold starting and overall good performance with little/no fiddling.  On my Rambler, it took some trial and error to get the combo of accelerator pump lever setting, jetting, and distributor advance curve so it didn't stumble off-idle, but now that it's dialed in I love it.  Pump a couple times and then push all the way to the floor to set the choke and it fires right up every time, with nice crisp throttle response.  I bought a new 2150 (and 2bbl adapter) from Gronk on eBay and he's in C. Springs.  He asks you where you're at when you order so the carb is supposedly jetted for your altitude.  The 47s mine came with ended up being too lean here in Boston at near sea level--runs best with 50-52.  You will definitely want to have an assortment of jets on hand while tuning (I got an assortment set online from Mike's Carburetor Parts for about $40).  I have the 1.08 venturis (287 cfm).    

I'm in process of building a 4.6 stroker with EFI, so I won't be needing this setup, would be willing to make you a good deal if interested for the whole package - carb, adapter, intake, and jets.  Its very nice, complete, and have only probably put 300 miles on the car since I put this together.  Only reason I'm not opting to just use this on my stroker is that with the additional displacement and more aggressive cam I'm going with I need more like 400-500 cfm to support the engine's potential at higher rpm.  I'm betting if I didn't have my foot hard in it this setup would work just fine lol.
That which does not kill us makes us stronger...
Back to Top
tomj View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Jan/27/2010
Location: earth
Status: Offline
Points: 7522
Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Oct/22/2017 at 4:36pm
As others point out, you are comparing apples and oranges. Closed loop feedback fuel injection in an engine designed with hydrodynamic computer simulation and the latest metallurgy with a thing designed with at best electronic calculators, and, a carb with the fewest powsible number of circuits to get the job done.

Modern (sic) carbs are much more tunable but vyiu have to pay money for them. The weber 38/38 has idle screw, low speed jets, main jets and low to high speed compensation jets, plus emulsion tubes for crazy fine tuning. More expensive Weber's have even more tunability.

Carter/Edelbrock etc can be forced to to better.

But maybe you should simply buy an EFI setup.

My 63 classic wagon with auto trans and a GM tbi system got a solid 20 mpg, 60 - 70 moh freeway. Doesn't get much bteer then that.

They are old cars. They do old car stuff.
1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5
http://www.ramblerLore.com

Back to Top
 Post Reply Post Reply Page  <12
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.03
Copyright ©2001-2019 Web Wiz Ltd.

This page was generated in 0.125 seconds.
All content of this site Copyright © 2018 TheAMCForum unless otherwise noted, all rights reserved.
PROBLEMS LOGGING IN or REGISTERING:
If you have problems logging in or registering, then please contact a Moderator or