Just installing a new set of Weber 44IDF carbs on a 2180 T-IV engine.
In an effort to reduce R&D time I was curious what choke & jetting combinations are out there.
Looking for street not race set-up Good idle & midrange torque
The new Carbs come with:
Choke: 36
Main: 135
Air: 175
Idle: 50
Which is where I'll start

Thx, in advance

What is your elevation - or the elevation where you will drive the car?

Looks pretty good, but I'd start with a bigger idle.

Do you have an AFR gauge?

Yes #55 idles would be better,for driveability I would go to 32mm venturies otherwise you will have poor lower end performance,thing is that's the range you drive in most.

Good luck

I'm assuming you have the F11 ET. Your AC jet is too small. In sizes below 2.00 it will enrichen the mixture as velocity increases.

Start at 2.00. If you need to richen it up at higher RPM go smaller. If you need to lean it up go larger.

I think your main jets are in the ballpark albeit, on the small side of it.

36mm vents should be ok with a 2180. If you stick with the F11 you might need to drop down to 34's to avoid a lean transition. The F7 may richen it up a bit to let you stick with the 36's.

I'm at sea level. (OK 800 ft. above). Same size engine. 44IDF Webers with F11 emulsion tubes, 32mm venturis, 130 main jets, 175 air jets, .55 idle jets. Without an AFR gauge, (which I should have but don't), it takes some experimenting. I'm pretty happy with the carbs set up this way. It's not perfect but runs great. Someday, soon, sometime in the future, maybe, I'll get off my ass and have the air/fuel mixture checked.

My engine and jets: recent engine rebuild to 2.4 L. Idle jets - 55, main jet - 145, air jet - 215. Good smooth running. New air/fuel gauge installed, running at 3000rpm, 5th gear, level road, sea level, ratio ranges between 12.7 and 13.1. Plugs are slightly sooty on outer ring, with electrode ceramic collar showing dark brown. Still too rich, and if so, what would you try next to lean it out some more?

Your jetting is where I would start for the OP.

To lean it out a bit you could drill out 50 idles to 52 or 53. You could also drop your mains down to 140. You may have to drop down your AC jet if the mixture goes too lean at higher RPM. I would do the mains first since it's the quickest and easiest.

Thanks, I will report back.

Lots to ponder. I also purchased a set of 34mm chokes. The carbs come with F-11 E-tubes and I'm at sea level. It would appear that Things should be fairly close, I do have a LM-2 AFR meter to see where things are at. I'll report back in a week or so when the carbs come in and I get it running. I'm also installing the CFR-Tangerine throttle cable linkage kit, should be interesting.

Thx,
Bernie

The expense of a good A/F gauge is worth it. It makes tuning and jetting a lot easier.

Progress report on my new Type IV 2.4L twin Weber 44's: Have an a/f mixture meter installed (see earlier post) and am attempting to move "cruising" (3000 plus rpm) a/f from high 12's to high 13's. Started at idles of 60's, mains at 140, air's at 215, engine running smoothly. Changing mains to 135 made no difference other than a little hesitation around 2000 rpm. Changed idles to 55's -- able to adjust a/f mixture valves to get a nice smooth idle, and a/f mixture increased to high 13's. But serious engine hesitation through the 2000 rpm acceleration. Changed mains back to 140's with the 55 idles, hesitation reduced but still bad. Went back to 60 idles and 140 mains, --- good running engine but back to a/f mixture of high 12's . Have 220 air jets on order as the next trial. Any further comments?

220 ACs should help the flat spot. You could also try going down a size on the venturis.

Lots of people complain about the Innovate AFR meter as being unreliable.

Mine has been working fine for over 5 years.
BUT - I read that one of the problems with reliability is that the sensors get too hot.

I took a ~2" X 2" Aluminum Heat Sink from a computer CPU and drilled a hole through the middle that the sensor would poke through.
Then I counter bored the hole so that the sensor would seat properly.

Then I installed the heatsink between the exhaust and the probe and tighten by hand.
I'll see if I can find a pic.

You're fighting lean transition. Big jets can overcome it but you'll run rich.

You can do a couple things.

1- Reduce you vent size to bring mains in sooner.
2- Change your ET from F11 to F7

F11= Lean transition
F7= Richer transition

AC jets affect top end more so than bottom end. What's your AFR at 4-5 RPM?

*Note* Make sure your float level is set correctly. A low level will delay the mains coming in.

My chokes are 36. I will wait for the 220 air jets and try them as the next step, with smaller ventures as a follow up step if necessary.

What ideal a/f ratio at cruising speed does the "Brain Trust" recommend?

If this is a street car, I'd try 34 chokes. They should kick the mains in sooner and give you better low-end torque, which is much more fun on the street.

Changing from 215 to 220 AC jets will lean your mixture and not enrichen it. I suspect you'll see no change at low RPM or potentially it'll be worse.

AC jet sizes below 200 = enrichen
AC jet sizes above 200 = Lean

The bigger you go the leaner you get. Think of it as a straw with a T at the end. The venturi creates the suction on the end of the straw. The AC jet is the straw and the main and AC jets are on either end of the T. Air gets sucked through one side of the T and fuel through the other. If you make the air hole bigger you will suck more air. If you make it smaller it will suck more fuel.

Had to add you have 2 problems. Lean transition and rich mixture.

When you either reduce your vent size or change your ET's you'll need to reduce your main and idle jet sizes. Either way you go it's $80. It's also a crap shoot. One or the other may fix your problem but you may have to do both.

If I had to pick one for a street car I'd go with the vents first. If it was a track car I'd try the ET's.

how many turns out are you the air fuel mixture screws.

50 idles too small. I have a stock 2.0 914. running 55 idles 130mains 180 airs. 36 vents tuned with lm2. just like jmill recommended moving towards 32 vents. for low end . 1 turn out on air fuel mixtures.

old rule but good starting point 4x venturi 4x 36 =144mains.


2.2 engine any head work? 1 5/8 exhaust? cam? timing? All plays a part.

If no AFR I would start rich. 55 idles 140 mains 180-200 airs.

Timing ?

Thanks for the generous advice. I am waiting for the 220 air correction jets as my next step.
What air/fuel ratio at cruising speeds (say above 3000 rpm) is a good target?

Jake Raby posted his recommendation a while back. I can't remember what he said. I do know he pays more attention to EGT than AFR.

IMHO @ 13.5ish. I'd be happy if it stayed under 14 and above 13. I have an ancient Heathkit AFR so accuracy is a factor.

Thanks Jim, that is what I am shooting for, high 13's/low 14's at cruising above 3000rpm.

Keith, I'm jumping into this thread kinda late, but I have a 2430 built by a pretty reliable source *cough cough*.... it obviously has had a MASSIVE amount of head work done, but it was delivered with 44s, 160main, 190air, and 55 idle. Zoom in to see in the pic

Click to view attachment

Sweet! What size vents?

With jetting like that I would guess 36mm. You'd drown an engine with 160's and 32mm vents. 34's would be overly rich. My question is what ET and pump jets? If it's the F7, you have the same jetting as my old bug.

From a different thread but relevant.

very late to this thread
the 36mm vents are great for high rpm and racing
but on a street car
one that is fighting a transition

that is a clear sign that you need more air velocity to pull fuel through the mains..

the smaller vents (venture effect) will pull fuel during that transition problem where you are not seeing enough air speed currently

it will run better
it will have more mid throttle response
it will be faster....

unless your racing and can use your gearing to keep it always above that rpm

In the last couple of years ethanol enriched fuels, and varying oxygen levels in fuel blends have changed all the rules with jetting. Engines I used to optimize with a 140 main will want a 155 today, with no other changes... Thats just one example.

In terms of EGT and AFR....

The deathzone is 14:1 - 15:1 range to stay out of at WOT.

Once you go lean of 15:1 the EGT will drop quickly. But you need added advance. Will not work with centrifugal only advance distributor. (light load cracked throttle cond.)

When I tuned my bus (72 Westy) I ended up with...

28mm vents
47.5 idles
125 mains
180 air corrector
F11 tubes
Float height 10.5mm (ball not pressed gasket in place)
Float drop 32mm


At cruise on the highway (flats) with cracked throttle the AFR will hover 16-18.

Slight incline/hill with steady peddle the AFR will go mid-high 12-13.2 or so.

WOT and the AFR goes low-mid 12's - 13

Around town cracked throttle (light load cond.) 16-17 generally with slight bumps to 18.