engine and drivetrain Getting started on Rebuilding DCOE 40's-What size Needle Valves?

[TobyB]

You'll be fine with 32's until you start doing regular track days.

And the size of the float valve is almost academic unless you do.

1.75 is fine.  2.00 is fine.

 The bowls are gigantic, and will get you about a mile and a half

at highway speeds before you even notice your fuel pump's died.

So as long as SOME fuel gets in, you will never run out.

 

DO spend the money on the wideband.  DO let someone else 'tune' them, but then DO watch what they do and DO see what happens on the AFR.

DO keep your initial jetting, if it's not way wrong.

 

DON'T be surprised, if you do a good job of rebuilding them, if you bolt them on and they work great.

 

These things are like network wiring- there's a lot going on in there, but odds are, if you plug them in, they'll work.

 

t

[76dailydriver]

+1 on Toby's comment. I also run these on my 02 dcoe32. They work and I don't think are too small for our 2 liter. These where from alfa 2liters which i believe breathe more. Bolt on air horns only and if your running the stock brake booster you're limited unless you go angled or tii bb. I went angled with mine. Im running 32 chokes with 125 mains , 200 air cor., f9 immul.tube, and 50 or 55 idle jets... runs strong but could be better. AFR on the rich side 9-13... might drop air cor. To 190 and see.

[downhillwolf]

Everything is fine, by rebuilding be patient and strict. There are two things to be carefull of; to use cold start pistons in the same bore they were in(otherwise they wont fit and fuel and air will pass them), float level. All other things are easily corrected with jets and a bit of tweaking idle screws
Good ignition distributor helps a lot when it comes to multiple barrels carburetors, a lot of us went 123TUNE, msd or rebuilt original with electronic breaker points, so keep that in mind if you plan to tweak them to be almost perfect

[2002Scoob]

Everything is fine, by rebuilding be patient and strict. There are two things to be carefull of; to use cold start pistons in the same bore they were in(otherwise they wont fit and fuel and air will pass them), float level. All other things are easily corrected with jets and a bit of tweaking idle screws

Good ignition distributor helps a lot when it comes to multiple barrels carburetors, a lot of us went 123TUNE, msd or rebuilt original with electronic breaker points, so keep that in mind if you plan to tweak them to be almost perfect

 

Yup! 123Tune distributor has been on the list for a while, and thanks to an above post, Wideband AFR will be as well. 

 

I won't be rebuilding the block, or at least, I hope I won't be rebuilding the block. Compression looks good as-is, so unless there's something glaring when I pull the head, I'm going to keep the bottom-end untouched for now. 

[downhillwolf]

I don't think we understand each other. DCOE is having cold start mechanism with pistons. You  should keep pistons where they were otherwise there is a big possibility that they won't seal and too much air and fuel will get into some of the cylinders, wich can cause bad idle and problems with tuning them properly.

Edited February 2, 2016 by downhillwolf

[TobyB]

fwiw, the 'cold start pistons' are also called the 'choke' mechanism, although it isn't a choke or 'strangler' at all on the dcoe.

 

I agree, Blaz, those can leak, and the resulting mixture anomalies will drive you nuts.

 

It's the assembly behind the 'choke lever' plate- you'll see when you get in.  

 

t

[M3M3]

DO spend the money on the wideband. DO let someone else 'tune' them, but then DO watch what they do and DO see what happens on the AFR. DO keep your initial jetting, if it's not way wrong.

\

 

what toby said.  don't wait to install an WBO2 sensor.  do it now.

 

what books are you reading about webers?  step one is read a few to understand the relationships of all the jets/venturis/etc.  most books also have recommended settings for various engines and explain the process to get to those settings.  don't guess or just do internet searches for snippets of data.  read the theory.  it really helps.  there is an FAQ Tutorial that has basic install process and I believe has several recommended books to read.

[2002Scoob]

Right now I'm studying up with Pat Braden's Weber book. and disassembling one of the carbs as I go. 

 

And sorry Wolf, ya, I misunderstood you about the cold start pistons. Duly noted

 

And I'm taking my time, I've got all winter/spring to get this setup done right.

 

Was able to digg a bit deeper into one of the carbs,

 

Looks as though they're set up as the following

 

32mm chokes

Idle Jet- F8 45

Main Jet-132

Air Correction Jet- 195

Emulsion Tubes- E41

[2002Scoob]

Jet assemblies

 

You'd be amazed (or maybe not) the amount of grass threads I blew out of the emulsion tubes... 

[downhillwolf]

Right now I'm studying up with Pat Braden's Weber book. and disassembling one of the carbs as I go. 

 

And sorry Wolf, ya, I misunderstood you about the cold start pistons. Duly noted

 

And I'm taking my time, I've got all winter/spring to get this setup done right.

 

Was able to digg a bit deeper into one of the carbs,

 

Looks as though they're set up as the following

 

32mm chokes

Idle Jet- F8 45

Main Jet-132

Air Correction Jet- 195

Emulsion Tubes- F41

No problem mate, here just to help you

Emulsion tube e41???? common ones are f9 and f16 both good with 2002, this may help you better determine wich one to use because you can cpy someone setup and start from there... It's much easyer that to start from what you have.

Main jet 132? i think weber had them on 0.05mm step so 130 or either 135 as i know.

For nowdays your car would be better with F9 idle jet and size 50 for 2.0l engine.

And just to cut some expenses from you and work. Get your wishes straight and from start use airfilter or whatever because if you change something(velocity stacks, air filter, cold air intake...) For everything you need re-jet them...

Edited February 2, 2016 by downhillwolf

[downhillwolf]

And don't make the same mistake i did... Don't try bolt on filters, they are not good for setting up carburetors. You will have big trouble setting them.
My mistake!

Go with filter/s that have some air reservoir between filter and ITB's. At least 3-4 times displacement of engine/pistons capacity.
Old BMW engineers knew what they were doing.

[2002Scoob]

The mains are likely a 135 then... they're fairly corroded and hard to read.

 

I've decided to go with the Trumpets I have, and machine down the Auxiliaries to fit vs. buying new ones. It'll be a fun lathe project Worst case scenario I end up buying replacements if it goes wrong, but I think it's pretty strait-forward. 

 

As for the Air-box... that's a different beast.I need to relocate the battery to the trunk so I can run an intake hose to the front of the car, and I'm honestly thinking of making my own CAI box either out of a high-heat vac-formed shell, or laid-up carbon. we'll see. 

[76dailydriver]

I would buy a wide band before you start tuning your dcoes. I made a mistake by not and ended up with 100 plus $ worth of jets and such.. I also tried 34 chokes and found them unresponsive below 4000 rpm. I auggest to start with 125 or 130 mains. No bigger. I've always multiplied choke size by 4 and that will give you an idea where your mains should be. For 32 chokes - 125-130. Your idle jet looks lean. But then again each engine responds diff. What i learned? Buy a wideband... worth every dollar...

[Stevenola]

Maybe it's just me but that sounds like a bad idea, messing with the aux venturi just to fit some trumpets that aren't supposed to go there.

 

Heed the others' words - get an AFR installed - it will save you a ton of money in jetting as well as heartache.  Could also save you from washing your cylnder walls with gas or burning a piston going too lean.

 

Agree that whatever filtration/trumpets you decide to go with then stick with it because changes will affect jetting.  Close fitting filters make it run richer.

 

Another good investment for me was a jet drill set, allows you to start small and drill until AFR is correct instead of buying tons of different jets which adds up quickly.   Plus you can customize air bleed sizes to really dial it in.

 

The e41 emulsion tube and 132 jet tells me these are del orto parts, you'll at least need to get proper weber etubes, my old DCOE32's came stock with f9 tubes.  The main jet may or may not be right but the drill and AFR can take care of that.  The e41 tube will likely be super fat because delorto's draw the idle circuit from the main stack not from the well like DCOE's so they will be overkill.

 

 

I've decided to go with the Trumpets I have, and machine down the Auxiliaries to fit vs. buying new ones. It'll be a fun lathe project Worst case scenario I end up buying replacements if it goes wrong, but I think it's pretty strait-forward. 

 

 

Edited February 3, 2016 by Stevenola

[2002Scoob]

Maybe it's just me but that sounds like a bad idea, messing with the aux venturi just to fit some trumpets that aren't supposed to go there.

 

Heed the others' words - get an AFR installed - it will save you a ton of money in jetting as well as heartache.  Could also save you from washing your cylnder walls with gas or burning a piston going too lean.

 

Agree that whatever filtration/trumpets you decide to go with then stick with it because changes will affect jetting.  Close fitting filters make it run richer.

 

Another good investment for me was a jet drill set, allows you to start small and drill until AFR is correct instead of buying tons of different jets which adds up quickly.   Plus you can customize air bleed sizes to really dial it in.

 

The e41 emulsion tube and 132 jet tells me these are del orto parts, you'll at least need to get proper weber etubes, my old DCOE32's came stock with f9 tubes.  The main jet may or may not be right but the drill and AFR can take care of that.  The e41 tube will likely be super fat because delorto's draw the idle circuit from the main stack not from the well like DCOE's so they will be overkill.

 

 

loving the advice. I'm going to order F16 tubes, and F9 Idle jets, and hold off on the main jetting for the moment.

 

I think I'll also be ok machining the Auxiliary's... I'm basically going to be creating exactly these-

http://www.dellorto.co.uk/shop/weber-carburettors-parts/carburettor-parts-weber-carburettors-parts/dcoe-dcosp-parts/auxiliary-venturi-dcoe40-spring-clip/

 

Which, by all accounts, look exactly like my stock part, but machined down in order to fit the longer trumpets. They even look to be made from the same castings. 

 

The trumpets I have are the slot-in style, meant to work with the Auxi's that have machined barrels.

http://www.dellorto.co.uk/product-category/car-accessories/car-air-filters-trumpets/slot-in-weber-type-trumpets/