Calling all Weber DCOE gurus

[Stevehose]

Ok my old Webers have arrived and I have begun the rebuild process. I disassembled one last night and here are the internal jet et al sizes:

40DCOE32 carb base
4.5 aux venturi
32mm choke (I think, they are so worn out and pitted that the stamp is off them so I don't know if they have been swapped at some point)
125 main jet
F9 emulsion tube
200 air jet
50F8 idle jet
40 pump jet
60 pump bleed
200 needle valve

My question is, for a stock engine and street use (I'd rather have torque and streetability than WOT performance), do these settings make sense? Anything look unusual? Apparantly these were on a coupe years ago so I am figuring (hoping) that this combination was set up for this engine, but am a noob at Webers and I can't find any jetting info on the web for 3 Liter M30's. All the charts stop at 2 Liter engines. Thanks.

 

[Stevehose]

Just found some old posts for 40 DCOE specs:

from Honolulu:

Choke 34
Main Jet 120
Air Correction 180
Emulsion Tube F11
Pump Jet 40
Idle Jet 55F8
Aux Venturi 4.5
Float Level 8mm

from Tirefreund:

Choke 34
Main Jet 140
Air Correction 180
Emulsion Tube F9
Pump Jet 40
Idle Jet 50F9
Aux Venturi ___
Float Level ___


Would these be for street or track and how does this compare to mine or how should I proceed - as is or make some adjustments?

Any current triple 40DCOE owners please feel free to let me know your specs, it would be much appreciated thanks.

 

[Stevehose]

Help, my wife is not amused! 2 of the 3 carb internals spread out on the dish towel! Any feedback on jetting appreciated!

 

[JFENG]

Suggestion

I would call Korman, tell them you need to buy DCOE jets/etc. THen tell them exactly what you're trying to setup and ask them what a good starting point is.

Buy the misc stuff you need and start from there.
I'd also call a dyno shop to see if they have a good tail pipe sniffer, and if yes I'd book a couple runs there to check your progression phase (super light throttle and tip-in), mid throttle and WOT phase.

John

 

[rsporsche]

Steve,

email carl bennett at korman. <[email protected]>
scott

 

[61porsche]

You lucked

out again with the 32s. They're no longer made. Keep em.( Well- Rennsport custom makes them I think) That's what makes torque.

I'd buy two more sets of larger mains and 1 set of larger idles for tuning. But start with what you've got. Honolulu's is closer to stock and sea level.

You're fine on the rest.

If you haven't found out yet- the mixture screws setting will be 3/4-1.5 out. Don't use the later( newer carb) settings. You're going to have to figure out you're distributer advance. Webers are sensitive to advance. You can try to dial in about 6 more degrees advance to help the bottom in. I wouldn't use the carb ports. You can also alter the larger spring in your distributer- make it looser. Find someone with a Sun distributer machine.

Email VGS- they are the German BMW Weber guys.

 

[Stevehose]

Problem is I am missing one of the chokes and they are so worn out that the ID stamp is off so I don't know for sure what size they are. I measured them as best I could and they look about 35-36mm at the narrowest point inside. So given this should I get 32 or 34's - I can get either. I want torque but don't want to stifle too much top end - would this happen with 32's?

out again with the 32s. They're no longer made. Keep em.( Well- Rennsport custom makes them I think) That's what makes torque.

I'd buy two more sets of larger mains and 1 set of larger idles for tuning. But start with what you've got. Honolulu's is closer to stock and sea level.

You're fine on the rest.

If you haven't found out yet- the mixture screws setting will be 3/4-1.5 out. Don't use the later( newer carb) settings. You're going to have to figure out you're distributer advance. Webers are sensitive to advance. You can try to dial in about 6 more degrees advance to help the bottom in. I wouldn't use the carb ports. You can also alter the larger spring in your distributer- make it looser. Find someone with a Sun distributer machine.

Email VGS- they are the German BMW Weber guys.

 

[Nicad]

I have read many weber applications don't bother with the chokes and accept a bit of stumbling when dead cold. On my car there are no chokes hooked up.

 

[61porsche]

I'll put it

this way... if your engine was highly modified then yes to 34s. My recommendation is to run what you've got. The Porsche guys would kill for that size on a 3.0 or 3.2 ( Those that chuck FI)

If by chance the solution was 36's you might as well step up to new dcoe45s. But in order for those to work well on a street car you have to choke down on them.

Your carbs are 32s by their descriptions. It's always better to not over carb a motor.

No you're not loosing top end. Get the mixtures spot on. In fact, I'll say to keep the carbs slightly lean rather than Zeniths which idle and off like to be rich.

Triples can flow faster and the transition is where you loose vacuum/ efficiency which is the second thing in the tuning process. Smooth transitions without going rich.

Yes, Bob you're right about chokes in that context. The word we should be using in this instance is venturi.

 

[Stevehose]

OK 32's it is - thanks for the input. I'll put the existing jets back in and tune from there.

Yeah Bob for cold starting the Zenith's say "choke" and the Weber's say "cold start." Choke for Weber refres to the main venturi size, along with the aux venturi size, which can be changed out. Different lingo.

 

[Nicad]

WHen I get mine apart, I'll add to what is inside. Might be a while at the rate i am progressing.

 

[Stevehose]

Do you have DCOE 40's or 45's?

WHen I get mine apart, I'll add to what is inside. Might be a while at the rate i am progressing.

 

[jmackro]

Any feedback on jetting appreciated!

Steve:

My "bible" on DCOE jetting is the paper by Dave Andrews at: http://7faq.com/owbase/ow.asp?HowDoI%2FTuneWeberCarburettors

Based on your engine's displacement, max hp rpm, etc. Andrews advises what jet sizes will get you close. From my experience no one can just tell you the perfect jets for your particular engine, altitude, fuel octane, ... there are just too many variables. I use the Andrews' formula to get close, and then an O2 sensor to fine tune.

I have always found that the "enrichment device" installed on DCOEs works pretty well. Many people don't hook up the e.d., and accept hard starting & poor cold running - I've never understood why.

 

[Nicad]

Do you have DCOE 40's or 45's?

I have 45s and headers. I sure hope my car has some decent mid range torque when back on the road.

 

[Stevehose]

Pull out the aux venturi followed by the choke to see what size it is - this will begin the story-I am just learning

I have 45s and headers. I sure hope my car has some decent mid range torque when back on the road.

 

[Stevehose]

Thanks I have read this but the chart stops at 2 liters and can't extrapolate the venturi size further. The other info on jetting is great.

Steve:

My "bible" on DCOE jetting is the paper by Dave Andrews at: http://7faq.com/owbase/ow.asp?HowDoI/TuneWeberCarburettors

Based on your engine's displacement, max hp rpm, etc. Andrews advises what jet sizes will get you close. From my experience no one can just tell you the perfect jets for your particular engine, altitude, fuel octane, ... there are just too many variables. I use the Andrews' formula to get close, and then an O2 sensor to fine tune.

I have always found that the "enrichment device" installed on DCOEs works pretty well. Many people don't hook up the e.d., and accept hard starting & poor cold running - I've never understood why.

 

[jmackro]

Thanks I have read this but the chart stops at 2 liters and can't extrapolate the venturi size further. The other info on jetting is great.

The text in the Andrews paper reads: "Below is a chart showing approximate idle jet sizes for given engine sizes, this assumes one carb barrel per inlet port E.G. two DCOEs.".

So, if you have a 6 cyl 3 liter engine with 3 DCOE's, you have 500cc/cylinder and 500cc/carb barrel. In other words, a 3.0 liter engine with 3 DCOE's is equivalent to a 2.0 liter engine with 2 DCOE's.

 

[rsporsche]

i'm no expert on this, but wouldn't a 2 liter (4 cylinder / 2 carbs) and a 3 liter (6 cylinder / 3 carbs) basically run a similar setup? the variables come from the engine configuration. for instance a stock 2002 might require a little more than a stock pinto.

i had 45's on my highly modified 2002. most people ran 40's even with some reasonable modifications.

 

[Stevehose]

Your engine probably has been modified internally to run the 45's.

I have 45s and headers. I sure hope my car has some decent mid range torque when back on the road.

 

[jamesw]

I have another car with a 2L engine and dual Solex carbs - so very similar - i.e. .5L/cylinder. It's an 8 valve engine.

I run Solex 44's - 40's are too small.

I use 34mm outer venturis and some even prefer 37mm!

Exhaust headers are 1.5" to the collector.

Why does the 3.0 engine perform differently? Does the head flow that poorly? Anyone have some head flow-bench numbers?

Cheers
James