Rejet the 44's or buy some 40's?, Yay, more carb questions. Options

[LowGT]

I have a stock 2.0 with dual weber 44's and a unilite. I had the 44's on hand, so if I rejet and change the venturis will it be like a 40idf? Or is there some significant difference between the 44's and 40's that make that not possible? Right now they are pig rich, as expected.

Right now it's:

36 venturis
50 idles
200 air correction
145 main
F11 emulsion

Proposed change #1:

Redo the 44's

32 venturis
45-50 idles
180-210 air correction
120-125 mains
F11 emulsion
(as you can tell, I don't know. From all the posts I searched this seemed like the area people were in with 40idfs)

Proposed change #2:

Sell the 44's, buy a set of 40's. Tune from there.


So which would you do? If you suggest keeping the 44's what would you recommend for jetting venturi?


Thanks! I need all the help I can get. (IMG:style_emoticons/default/biggrin.gif)

[Aaron Cox]

what cam and what do the heads look like? also.. what kind of exhaust?

my hot cammed 2.0 with a header runs
44 IDF's
34 vents
135 mains
55 idles
175 airs

i have some 32's i can throw in.... but my motor currently is a power monger between 3300-6000+

i think you will be better off with 40's and a 32 vent....

wait for jake/etc to chime in

[So.Cal.914]

IMHO keep the 44's rejet and change venturi's. If you plan to build a monster in

the future and you are going to run carbs, the 44's should do nicely.

[LowGT]

what cam and what do the heads look like? also.. what kind of exhaust?

Stock cam, stock heads, stock HE's, monza muffler (soon to be bursch).

[Aaron Cox]

32's or 30's for the vents imho

[Twystd1]

What Aaron said.....

Me personally, I would get 40s or 36s unless you are going to build a bigger engine in the near future.

I think the general assumption is that a 44 will work just the same as a 40 if you vent it the same.

In my humble I don't know shit opinion. And after working on more webers that I can remember.

It ain't so........

I believe the transition ports are a differant drill size and the internal idle circuitry has bigger conduits. (my guess on this)

I wish Art Thraen was here to tell us all EXACTLY what the differances are.

Jake... can ya get Art to jump on the 914 club and tell us once and for all what the differances are between the 40 and 44?

Other than the obvious........

I for one have had only one REAL success on a bone stock 2.0 litre engine that worked reasonably well with 44s. (vented to 30 I think)
And that had a HEADER.
Not stock heat exchangers.
The header made all the differance in the world as far as tuning that engine.
It also had a big CDI box for spark. That helped also.

ALL of the rest of the cars that I have tried to tune correctly with 44s have been a mediocre success.. At best. They ran OK. But just OK.......

I know there are a couple of guys here that have made it work.
And from what they have written. It apparently works well.

We would have to dyno that combo to REALLY know how well it works.

Many people who have done the carb conversion on a bone stock engine. THINK they have improved performance greatly.

This is simply because their injection system was so fucked up...
Therefore the carb setup FEELS like the engine is running better than it ever has before. (and probably is)

Truth is. In most cases. I would bet the Factory FI would give better performance and mileage. Especially with a stock exhaust on a bone stock engine.

You also have the opportunity to MegaSquirt or use some other FI brain to fix your problems.

In this scenario. You leave the injectors as is, the manifolds as is, the TPS as is. And shit can the rest of it.

Yeah there is more to it than that. But thats the basics.

Cost ya bout 350.00 to 900+ for a brain that would work and still have the opportunity to have complete EFI (includes ignition) at some point in the future.

Hopefully some of the fellas that have dyno proven results with your exact combination will chime in here. That way we can differentiate fact from fiction...

Cheers,
Clayton

[old dkp]

This is old school from 16 years ago. with a 2.0 44mx carbs 32 vents. 130 mains . 200 airs. 60 idle. with f 7 tubes . then i changed the heads to 1.8 Now the carbs are somewhere in the rafters.

[Jake Raby]

Listen to last weeks Radio show- I went over the 44mm in detail and covered this subject pretty well on the Venturi front as well as jets. Art was last weeks guest on the show..

The 44mm carb is very universal for a TIV. I have used them on engines from 90-210 HP!

[Twystd1]

I will defer to Jake as far as making 44s work.

So Jake, What do you suggest for jetting and vents on a bone stock 2.0 with heat exchangers.????

C

[Aaron Cox]

I will defer to Jake as far as making 44s work.

So Jake, What do you suggest for jetting and vents on a bone stock 2.0 with heat exchangers.????

C

at WHAT ELEVATION?

[Twystd1]

Good call Aaron.

My bad. I assumed all of Texas was relatively below 1000 feet.

C

[JPB]

Stock SDS, hopped up SDS, just to have a great driver SDS. Carbs farewell, SDS hello moma (IMG:style_emoticons/default/biggrin.gif)

[LowGT]

Listen to last weeks Radio show- I went over the 44mm in detail and covered this subject pretty well on the Venturi front as well as jets. Art was last weeks guest on the show..

I checked out the 10/20/06 show. I've run stainless fuel line in the tunnel, new CB rotary pump, new filter. The tank was also cleaned.

It sounds like sticking with the 44IDF is the appropriate choice, and it seems like 32 vents are your preference for a 2.0. I didn't hear much talk about jetting, there was a main jet reference for the bus guys but that's all I heard.

Any baseline jet settings for a customer that bought a unilite a month or so ago. (IMG:style_emoticons/default/beer.gif)


(For those who inquired above, Dallas is 450-600 ft above sea-level depending on where you are in the city.)

[LowGT]

Okay, so I've been reading this page. http://www.aircooled.net/gnrlsite/resource...les/jetting.htm

I've come up with:

44IDF
32 vent (from Jake)
F11 emulsion
135 main
45 idle (I still have 50s to fall back on if it's too lean)
200 air correction.

Does this seem like a decent starting point? I $16 per set of 4 jets, I don't want to be too far off or I'll spend a fortune in jetting.

[Jake Raby]

That main is a little fat more than likely for a 32 vent. I'd try a 125 or 130 with the 200 air. It'll probably like a 50 or 55 idle, when you go down on vent typically the engine will want more idle jet than previously, but less man jet..

Jetting isn't as dependant upon engine size as it is venturi size. The genarl rule is for venturis up to 36mm multiply the vent times 4 for the baseline main jet. For vents over 36mm multiply times 4.2... I have taken a set of carbs off of a 1.7 and bolted them on a 2270 and the jetting was perfect for each, even though they were 75HP and near 300cc apart...

[Carlitos Way]

I apologize for the hijack... but this one is killing me and is very near...

I have a set of 40 Weber IDF's.

32mm venturis

F11 Emulsion (since, replaced by F2’s)

50 idle (later upgraded to 55’s due to severe sputtering in transition)

125 Main

180 Air

It has been suggested I should go up to about 200's on the air jets.

Elevation is about 1000 feet.

[Jake Raby]

The F2 emulsion won't get you too far..
What are your issues, what are you trying to do?

I use 200 airs for most everything unless the application is above 4,000' as they provide the best tuning in general.

[Gint]

The F2 emulsion won't get you too far..
What are your issues, what are you trying to do?

I use 200 airs for most everything unless the application is above 4,000' as they provide the best tuning in general.

Oooohhhwwww!!!!

I'll have to bite now. What airs would you use above 4000 feet? For those of s that live in rarified air.

[Carlitos Way]

Jake,

Issues: Stumble (pretty bad) at low RPM's (anything under 3000 RPM). Car lurches like it wants to go and leaves me just short of whiplash.

High RPM's, they work and sound absolutely wonderful. Idle is pretty smooth.

Ideal would be a "driveable" street car that can not only put around town but also enjoy some 3500 RPM sustained driving on the canyon roads.'

Insight is much appreciated.

[Jake Raby]

What dizzy are you running?? Most 3K and under issues are linked directly to less than optimum timng advance and not the carbs at all..

Other than this you could have a partially blocked idle circuit that is flowing enough for the car to idle, but thats all.

With that one, I'm out of here for a while fellas.. My new forums open November 1 and I'll be giving it all my spare time... Tons of new tech articles will be found there, look for the link on the 1st..
See ya.