Ok i have a question, took the stock 2 bbl off and am thinking about getting it rebuilt. Now since i have a 390 what is the cfm for these carbs?? Always thought a good 2bbl would almost beat a 4 bbl except for the seat of your pants thing. From lurking i have learned that alot are running 600's with some running 750's of course these are 4 bbls but i wonder if my stock 2bbl can be tweaked to get 500?? The stock but tweaked inside of a motor has always appealed to me. Looked everywhere for any numbers on it but only ones i can find is a 1 and a 5 has a manual choke and is pretty dirty cleaned it off some but only could make out those numbers so no tag anywhere. I did notice that the butterflies where alot bigger than on a Holley 2 bbl. Another thing... did the cj heads only come on mustangs and galaxies?? Will the stock valve sizes keep the torque where i want it or should i go for bigger valves in the stockers if i can't run across any cj heads?? Looking at $800 just for cj cores so might stick with stockers until i can do a full rebuilt on it, for its age it still runs pretty good so i am gonna drive it till she pukes. Learned quite abit from lurking and just want to say thanks to all for your knowledge.

 

I think those 2 barrels are 500 cfms. It's a different deal but the Nascar Nationwide series runs on 390 cfm carbs. How do you use the truck?

Look between the two middle spark plugs on the heads for a number like C8AE-AA (I made that one up) and report back what you have.

For a daily or occasional driver the 2 barrel will be OK. You will never make up the money spent on carb and manifold upgrade in mpg savings.

About 600 cfm carbs isall the 390 can use on the street. Go look and sniff the tail pipe, if it is all black, sooty, and stinky, it is dumping unused gas out on the road now. IMHO


John

 

Truck is out at uncle's i probably won't get out there for another 3 months. Just assuming i have plain jane heads plus its cold as a witches tit here right now hard to wrench when your fingers are frozen. Might just keep the 2bbl only gonna get 10 mpg anyways with a 4bbl probably be closer to 6 can't seem to keep from spanking those rice burners with fart tips LOL. Thanks for the info

 

You could prolly tweak it up, add electronic ignition like a Pertronix for a little better mpgs, and still whoop the ricer.



John

 

I have a 360, I just spent 4 days strait switching from a 2bbl to my new edelbrock performer 600 street / economy, i got for X-mas, I found a Edelbrock streetmaster intake. with my 2 bbl, while pulling my horses around my foot never left the floor unless i was coasting down hill, but i was able to get a steady 13 - 13.5 mpg on highway (dry load). during my big upgrade my dad found my mechanical time advace froze up (he fixed that). With that motor totaly stock exept my new carb and intake, doing 60mph it will now just lean your head back and pull like hell compared to my slow poky crap a** 2 bbl. So far the bloody nuckle and headace is worth the work (so far), i haven't even gotten a 1/4 tank through and my hands are still stained of oil from the job.
my question is, do headers make a big enough difference to worry about putting on? does dualing out help out enough to justify the cost to have it done?
with a stock motor with only a carb what would be the next best thing i can do to make it pull my horse trailer up the mountain pass better, and might help my gas milage on dry load?
any help would be great

 

I know it will be a hard argument but I doubt the carb and intake made that kind of difference alone. I suspect the dizzy tuneup and resetting the timing had a lot of influence.

A 4 barrel has smaller primary's and can flow more gas at WOT, but these engines aren't starving for gas running the 2 barrels.

my 2 cents


John

 

Where you at?
They changed the setup, can't look for myself anymore.

It was always kinda crappy a guy wouldn't bother to say where they were
to make it easier on those helping them out to start with but now it's even
worse. :/

What elevations?

Back when I lived at Hayden Junction AZ ~1900ft I had a lot of trouble going
over Pinal Pass (a measly 5000ft) and could feel the "full power circuit" in the
stock 2100 carburetor kick in and actually reduce the power.
No kidding but YMMV.

So one day (without burning any bridges) I disabled the full power circuit and
the next weekend went from having trouble in 3rd gear and shifting down to
2nd quite a bit, flew over that pass in 4th gear and was more heavily loaded
than usual too BTW. (camper shell full of stuff and a dune buggy in tow)

Nope, it wasn't just the main jets danggit. ;)

Later on an automotive newsgroup a guy told me if I really wanted to get more
power from an old FE and 2100 carburetor was to "richen the full power circuit,
they are all too lean". He was on the coast of Californy. ;)

Ooops huh? ;)

Figure out what's going on before throwing money at it.
"a half-wit-child can plop money down on a sales counter"
You know it? ;)

Alvin in AZ
ps- Edelbrock and Scat are just a few clicks away LOL :)

 

Doggonit I can't find the information to quote exactly...

2 barrel and 4 barrel carburetors use two different vacuum levels when
they rate the CFMs ...so the numbers aren't directly comparable.

I know that sounds dumber than heck but that's the way they do it.

Alvin in AZ

 

thanks guys, today i finally toped off again from the half tank. with normal running around (i live out in the country - 10 miles from anything in any direction, sometimes farther) i kepted the cruise speed at about 60mph down the back roads. using ONLY primaries (NO secondaries at all) i did 104 miles on 9.5 gal = 10.9mpg, the truck also did a fair bit of ideling and peacing the neighborhood (tighting my steering box and a few maintaince stuff) so i would venture to guess about 11.1 - 11.3 mpg on primary only doing normal run around shopping.
my freeway mpg with the 2bble was 13-13.5, havent been on the highway yet with this carb to see what mpg will be, but feeling the peddle from 60 to 75 don't feel like i'm going to be useing much more (unlike my 2bbl i felt a difference in the peddle and still got OK mileage), It feels like it has potential to get better on the highway, but only time will tell?
would you consider that OK mileage, what i'm getting?
what else could i do to get better?
I have my hands on some headers, would they help enough to justify the hassle?
what about dualing out or just re-design the "Y" pipe?
or should i just leave it the way it is?
I appreciate all you guys help.

 

On the FE forum there's a couple guys that don't run headers for reasons
like heat and noise. Another thing to think about is the manifold bolts, the
guys on the FE forum brag on how few bolts they broke off when removing
manifold bolts. LOL :) But, the right hand manifold is one of the worst ever
exhaust manifolds ever made so the power and MPG rewards are real.

I'll prob'ly never put headers on my pickup. :/

Since my original exhaust pipe was still in dangged good shape but wanted
to re-route it just a bit (it was really close to the transmission's rear cross
member) I cut into it and discovered a real mess, that's still got me just a
little pissed off at Ford. The hole in the Y pipe was crap. :(

I opened it up and reshaped it so the two pipes come together like a 2 into
1 header. Made my sorry little 360FE feel like it went from a V6 to a V8. :)

http://www.panix.com/~alvinj/file12/exhaustY.jpg

What you see on the outside is basically what you'd expect to see on the
inside except I reached into it with a grinding wheel called a "plug" and made
it pretty as anything in there where it counts. ;) Made myself an extension
for the 4+1/2" little hand grinder to reach the plug down in there.

Anyway, that's what I did. :)

Alvin in AZ
ps- the idea of my posts are to just tell you my story, at that point it's as
if you've done it yourself and can take it one step farther and do it better! :)

 

the 2bbl fords, 1.21 venturi is 351cfm, 1.23 is 356cfm, and the biggest stock was the 1.33 at 424cfm. There are other smaller ones as well. 2bbl are rated at 3.0 inches of depression and 4bbl are rated at 1.5 inches of depression, there is a conversion but for the sake of time, a 4bbl flows a lot more air than an equal cfm rated 2bbl something like 1.5 to 1.6 times more.

The 2bbl can be made bigger, i have done many for racing, 1.38 venturi is safe and 1.43 can be done on a 1.33 stock model.

 

On the carbs in 4 barrel and priced decent is a quick fuel carb. Very tuneable and the optioned to run 1to 1 linkage if requested. I run a 830 on a 472 big block and love it. On a 390 need a little smaller and should do well. Have ran a couple of these carbs and all have worked well. People tell me this is to big but my problem is getting air into engine at high elevation. I live at 4000' and play higher everyday. I know their are many carbs out their but this one works well. I've been running holley's for years and prefer over the edelbrock and they run ok for what they are. IF your wanting low end torque definelty look into annular booster set up for low end torque. Also helps on fuel mileage because it helps vaporize the fuel better than a downleg and straigh leg booster at low rpm's. I run this and love it for low end and lugging around up in the mountains. Something to check into if you want. Drop me a note if you have any questions.

 

I am a big fan of annular boosters as well, the 2bbls have them, and so do the old 4100 autolite 4bbls. The holley's 4010 and 4011 that came out in the 80's have them as well many other higher end carbs.

 

can someone catch me up, i'm a little slow on some of these upgrades.
what does annular booster do? how does it work?
does it strickly help the low end or does it also benifit the midrange too?
My 360 is pulling anything from 2 - 3 tons down the road, could be highway or could be mountain passes, or just back roads.

 

Google is your friend. ;)
{annular booster carburetor}

Annular Vs. Dogleg Carburetor Showdown - Car Craft Magazine

Out of my collection of 2100 and 4100, carburetors only ran across one
"annular;)" booster assembly that was different from all the others, it has
flared out lower "lips" and came from the oldest 2100 I have (I believe it's
oldest).

The real trick to these old 2100's is actually in the emulsion tube hole
placement.

http://www.panix.com/~alvinj/file12/booster.jpg

That's a really sorry picture etc but shows the crummy type emulsion tube
laying loose with it's 8 holes all up near the top. The good type are installed
and also have 8 holes each. Big difference in power etc between those two
types of emulsion tubes! No kidding.

I'll use the scanner next time and get some better pictures. ;)

Swapping out booster assemblies is no sweat, but swapping out emulsion
tubes can be tricky and can make a mess of both booster assemblies. :/

Best to solder up holes and drill new ones in the emulsion tubes without
pulling them out of place. Some swap out good and clean and tight and some
don't, best not to gamble IMO. Besides you only have to have one booster
assembly for the "fix" then. :)

Pull your booster out and look at it, you might have the good type already.
If you don't, get back on here and I'll work with you on it and when you put
it back in, you'll be in for a pleasant surprise. :)

Or you can plop money on a sales counter for a new carburetor. ;) LOL :)

Alvin in AZ