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mrdew

Installed side drafts, no power WOT.

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Originally with this engine I had a 32/36 DGAV installed with a cannon intake manifold, and the car pulled half decently with it.... It would get up to speed relatively quickly and you could "feel" it when you got on it.

Now I have twin DCOE 40's installed with an Ireland intake manifold and a Delux Redline setup. I originally had a makeshift linkage to get the car on the road and I thought that that was just my issue. I installed the new linkage and verified that it allows for WOT, but absolutely no power. When you go WOT it occasionally "stalls" or loses all power and does not accelerate at all as if you shut off the ignition, but it never stumbles over itself. I have made the carbs extremely rich and lean to see if there was any difference, but there was not. I have the timing set to iirc 16 deg advance at 2,000 RPM. I am stuck in the mud right now.

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I am a DCOE newbie, but having gone through an extensive effort to get my new car with DCOE 45s running properly perhaps some of my experience can help. The thread on my issue with a lot of good diagnostic suggestions from 2002FAQ members is linked below. In my case it turned out to be a fuel pump that appeared to have good pressure and flow, but in reality it did not. A new Carter pump fixed the problem.

Can you say a bit more about the problem? It sounds like it is intermittent. Does the car sometimes pull strong to redline at WOT and other times not? What RPM does the problem kick in? Does it do it in corners or after hard braking, or is it just random?

Based on my experience, you might explain what kind of diagnostics you have, what the readings are, and what the engine specs and carb jettings are. A few questions to consider are: what is the actual fuel level in the float bowels; do you have an AFR and fuel pressure gauge installed; are you using a plug cut to verify rich and lean; are the carbs properly synchronized? Apologies if you are well beyond all this, hope you get it solved.

DCOE Help Update: Problem Solved

http://www.bmw2002faq.com/component/option,com_forum/Itemid,57/page,viewtopic/t,377659/

Fred '69GT3 & '74tii

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To note, it does have a carter rotary fuel pump. The problem is not intermittent and there are no vacuum leaks. The car does not pull at any RPM.

For instance:

From idle go WOT. The car will want to stop, basically shut off the ignition and so you let off and it comes back to life. After that you feather the throttle juts before WOT and it picks up speed but gradually. Eventually you go WOT and it does not change in terms of acceleration.

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It sounds like something is off with your primary set up. What are you running for chokes? You might as well list all the jets ect too. The more info the faster the fix.

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This is actually all my fault and I am sure i will be scolded for it, but I bought these off of a teacher and I was told that they were originally off another 02, and they were clean, did not even tear them apart.

What measurements do I need to get and how/where do i measure them?

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You can go to the site below, and about halfway down Weber DCOEs are listed. Find your model (stamped into a flat pad on the top of the carb top). This will give you an idea what your carbs came with for jets, etc.

I have 40 DCOE 18s on my 2002, with 2002ti manifolds and the internal specs listed, and it runs very well once tuned correctly, and using air horns.

The easy way to reach a baseline for tuning is to start with specs that you know work, and will usually need only basic tuning from there.

But, it sounds like you have other issues, probably with fuel delivery, to start with.

http://www.postdiluvian.org/~mason/moto/jetting.html

Hope this helps,

vince

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Yeah, I've yet to turn my new engine over, but I bought 40's online and immediately tore them completely apart, noted all jets, emulsion tube size, chokes, etc, etc...and got rebuild kits to just be able to start from scratch...they were already really clean when I got them, but that means nothing.

I plan on getting close with the jetting, based on the books I've read and stuff I've found online, but I will then go to Steve at Top End and have him do the final tweak on them, since he's a jedi with those things..;-)

Also, what's the condition of your engine? age, mileage, cam, etc?

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Go to www.racetep.com and enter their site and find the carb drawings they have a great exploded view of the 40's, the parts you need to record the sizes of, for starters, are going to be numbers 11 air corector jet 13 emulsion tube 15 main jet 16 idle jet 17 aux venturi and number 22 main venturi, report what sizes these are please. I kinda think you have something pretty simple assembled wrong like the aux venturis in backwards.

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This is actually all my fault and I am sure i will be scolded for it, but I bought these off of a teacher and I was told that they were originally off another 02, and they were clean, did not even tear them apart.

What measurements do I need to get and how/where do i measure them?

yikes. DCOE's are never a "bolt on" mod. you need to know how they work, what all the jets and measurements are, and how to tune them. suggest you stop playing with them and get one of the several recommended books on tuning webers and read it. then start asking q's.

seriously, not saying this to be a pain. having DCOE's on a car is an adventure. you need a map.

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Dcoe jetting will vary car to car anyway , depending on engine mods.

Go with the recommended jets and tune from there.

And get an AFR gauge.

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Ok so I pulled the jets.

Main Jet: 115

Emulsion tube: f11

air corrector: 200

Choke 36mm

Idle Jet: 45F9

Pump Jet: 40

Just because I set the idle mix screw to one turn out on each carb and slowly turned each one down and the car only stumbled when one screw was fully seated. It also tends to drip gasoline out of the chokes onto the ground.

My engine:

Stepped headers

Ireland engineering intake manifold

9.5:1 compression ratio

E12 Head

292 Camshaft

DCOE 40 151

Carter Rotary Fuel Pump

I do not have fuel pressure readings yet because I do not have a gauge.

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It also tends to drip gasoline out of the chokes onto the ground.

This says you prolly need a fuel pressure regulator/needle seats/maybe floats.

Read through Fred's two threads where we beat this one to death.

36 choke with 115 mains is for a healthy motor that either makes good vacuum

or runs flat out a lot. 200 airs backs this up- the motor these carbs came off

was efficient and drew a lot of air, thus also pulling a LOT of fuel. Or the

fuel pressure/float level was WAY too high...

And this could lean your mixture out so much that it's simply not lighting

when you open the throttle.

You DO know that you have to 'feed' in the carbs until you reach higher revs,

right? If you simply whack 'em open at 2200 rpm, it WILL fall on its face...

(but your original post seems to imply that you get that)

After the fuel pressure gauge,

I'd start by setting the timing to 36 degrees at 4500+ rpm.

Then I'd buy and install a wideband afm

Without the wideband, for a street car, I'd go to 32mm chokes,

125 mains and 180 airs.

And see what happened....

t

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The fuel pressure before is at +/- 3. What should it be at.

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