44's? I hope there is a Uni Sync in your tool box

 

40s, almost went with 45s, but meh.

I should get the 02 to tabout 140-150whp with these. If I can learn to tune them right it should be a nice big jump from the 32/38 I have now.

 

Ahh, 45 & 40. DCOE right? Sorry, my brain has been stuck on Mikuni for whatever reason. 40 is a solid choice. Now make all the old guys vomit and tune it with a wideband

 

Haha I will be tuning via wideband. Should be fun lol.

 

I'm planning to retune the Carter AFB on my Sport Fury with a wideband.

 

More delicious carbyness

 

I was simply jealous before. Now, I think I hate you.

 

It may be a bit before they are installed unfortunately. I'm picking up a new transmission this weekend, and hopefully installing it next weekend. Then I plan to drive the **** out of the car for a bit. Then when I get bored I'll put these babies on. I want to get the car properly set up before I add too much more power.

New fuel lines, new exhaust, some cooling stuff, and finish removing my A/C.

 

This sounds almost like every miata you have ever owned, but you never get to the drive the **** out of it part.

 

Not sure if serious...

I've been driving the **** out of this car since February.... It literally hasn't been off the road for more than a day.

I get what you are saying I guess, only time will tell. So far I've stuck to the plan. Right now my plan is to have these on by the fall. So check back then for the part out I guess

 

A few questions.

What is the RPM range of that motor? What size choke is in your 40mm carbs?

 

Redline is 6500, max torque at 4350, max power at 5700. I have to contact the manufacturer to get all the specs on the carb. Probably Monday since I have to call them anyway. Or is the choke something easy to find by just looking?

 

You maybe able to see a stamped number on the choke as you look through the intake side of the carb. On a 40 DCOE, they range from 26mm to 36mm.

 

I see 30.

 

This is what I have... or supposed to have. I see 30 stamped so I'm guessing this means my main Venturi is 30 and not 32, which worries me already.

Part # 19550.174
Main Venturi: 32
Aux Venturi: 4.5
Main Jet: 115
Em Tube: F11
Air Corr Jet: 200
Idle Jet: 45F9
Pump Jet: 40
Pump Exh: 50
Needle Valve: 1.75
Choke Type: Manual

This looks to be how they come from the factory... which if correct makes me a bit angry as mine was supposed to be "Set up for a 2002" from the people I got it from. This is what I've read is recommended for my engine:

Typ. BMW 2002 Dual 40 DCOE Conversion set-up:
Main Venturi/Choke - 33
Aux Venturi - 4.5
Main Jet - 120
Emulsion Tube - f16
Air Corrector Jet - 190
Idle Jet - 50f8
Accel Pump Jet - 40
Pump Ex Valve - 55

Also found this, guy said it runs beautiful with this setup:
needle/seat valve 1.75
Emulsion tubes F16
air correctors 170
Main jets 120
idle jets 55 (no f number on these)
pump jets 40
main venturi/choke 33
aux venturi 4.5
exhaust valve/jet (bottom of float bowl)55

Yet another with my setup:
33mm main venturi
4.5 boost venturi
120 main jet
F16 emulsion tube
190 air corrector jet
50F8 idles
20 pump jet
55 pump valve

 

If it is a 30, it will not be enough. When you change the main venturi (choke), you have to change pretty much every other jet.

You are lucky to have found ideal set ups. I had to trial and error my way to the right parts. Unfortunately, you are going to hate how much it costs when you buy tuning parts. Once it is right, you will not have to mess with it much unless you make big changes to the motor.

 

Well I'm going to be calling up this place I got mine from tomorrow. I was supposed to have it properly set up for a 2002. I see from the formulas that the main venturi is not even close. That means probably the rest of it is not set up right. I may just return the whole kit if they don't make it right. Then start over with another company and ask a few more questions before I buy everything.

Luckily I'm not in a rush to install this stuff, and I want to have it as close to right when I bolt everything on.

Also why do I need to change jets with the venturi? Are they made for each size? Do I need a 32mm venturi jet or something? Or do you just mean if I had it running pretty good on 30mm, then changed to 32mm I would have to change all my jets because of the bigger venturi?

 

A smaller choke creates a higher vacuum at any given rpm. Vacuum is what draws fuel from the bowl before being distributed to various jets. A smaller choke with more vacuum will pull more fuel per jet size than a larger choke size.

The choke is what controls air speed into the cylinder head. Smaller chokes usually have more low end grunt, but runs out of breath at a higher rpm. Larger chokes will have less low end grunt, but will have more air available at higher rpms.

Edit: This is one of the advantages that Weber carburetors have over most fuel injection set ups. You have the ability to tune air speed just before entering the cylinder head.

I first started out with a 36mm choke. I first went down to a 34, then 38, then to a 40 which is the largest choke size for my DCOE 45s.

 

Well I talked with the guys at racetep, who have done a lot of BMW 2002 work and they swore to me that the 30mm was good for my engine. They said they swapped the 32s out for the 30s when they shipped my order and that the jets, etc... are what they use on their own 2002s.

So with that being said I'm going to give it a go with the 30s and hope they didn't just lie to me to get me off the phone.

 

You can always change them out if you think it is a little weak. I just don't see it being enough for a performance set up, but I only know one set up well.

If you want a second opinion, you should consider calling Pierce Manifold.