Triple Weber DCOE 40 Emulsion tube quest.

[Texasroadrunner]

I've been tuning my '72 L24 with Triple Weber DCOE 40's for some time. I have successfully used my wideband sensors to read the air fuel ratios at various loads and throttle openings. Idle mixture, Idle jets and main jets are working well. My issue is the lean zone at mid throttle. The recommended emulsion tubes are F11's. They are too lean. I have richened them up some by soldering over the top 3 air holes and reducing the air bleed jet size. Do any triple Weber DCOE 40 people have success with a certain number emulsion tube? Like maybe the F16? If you have, please let me know. New emulsion tubes x 6 aren't cheap so I'm not going to buy them all. I did try a set of F9's but they were even more lean than the F11's. Thanks for any DCOE experts that have cured this problem and can help.

 

[TB24O]

I've been tuning my '72 L24 with Triple Weber DCOE 40's for some time. I have successfully used my wideband sensors to read the air fuel ratios at various loads and throttle openings. Idle mixture, Idle jets and main jets are working well. My issue is the lean zone at mid throttle. The recommended emulsion tubes are F11's. They are too lean. I have richened them up some by soldering over the top 3 air holes and reducing the air bleed jet size. Do any triple Weber DCOE 40 people have success with a certain number emulsion tube? Like maybe the F16? If you have, please let me know. New emulsion tubes x 6 aren't cheap so I'm not going to buy them all. I did try a set of F9's but they were even more lean than the F11's. Thanks for any DCOE experts that have cured this problem and can help.

Hi texasroadrunner, had my 240 tuned on rolling road a year ago at Northampton motorsport and was very pleased with result.
Tuning triple Webber’s can depend on a lot of things and mods you have , camshaft, exhaust etc but I tell you what went on.
My 240Z had a total engine and head strip down with new components, has triple Weber period correct Italian ones Dcoe 40 high lift Piper fast road camshaft, lighten flywheel, sports manifold and exhaust etc
The emulsion tubes are F11
They replaced the mixture screws for a later type which have a much longer taper( better mixture adjustment) Dcoe screw long40/45 (6475000300) with springs (4760000700) also new idle jets and main jets for standard setup for 240z
Adjustments done for power curve and also retarded ignition from 30 def max to 22 which improved power and torque right through the rev range and stopped the engine detonating at full throttle.
Extremely happy with results hope you find this information of some use to you, good luck
Regards Tim

 

[jonbills]

I had Dellortos, so no direct experience. However:
1) Bigger idle jets might help - they supply the progression holes.
2) My Des Hammill book suggests f15 or f16 emulsion tubes.

 

[Texasroadrunner]

Hi texasroadrunner, had my 240 tuned on rolling road a year ago at Northampton motorsport and was very pleased with result.
Tuning triple Webber’s can depend on a lot of things and mods you have , camshaft, exhaust etc but I tell you what went on.
My 240Z had a total engine and head strip down with new components, has triple Weber period correct Italian ones Dcoe 40 high lift Piper fast road camshaft, lighten flywheel, sports manifold and exhaust etc
The emulsion tubes are F11
They replaced the mixture screws for a later type which have a much longer taper( better mixture adjustment) Dcoe screw long40/45 (6475000300) with springs (4760000700) also new idle jets and main jets for standard setup for 240z
Adjustments done for power curve and also retarded ignition from 30 def max to 22 which improved power and torque right through the rev range and stopped the engine detonating at full throttle.
Extremely happy with results hope you find this information of some use to you, good luck
Regards Tim

I do have the older DCOE 40 18's that have the shorter idle mix screws. I didn't know that you could swap them out for the newer longer tapered style. That would make setting idle mixtures not so touchy. I'm glad you can run F11 Emulsion tubes with a long duration, high lift cam but also I'm amazed. I run a Comp Cam 260 which is street friendly and makes high torque from Idle on up. Also, I run the higher compression E31 head with 32 degrees max advance and 18 degrees at idle. Thank you Tim, for the needle and spring part numbers.

 

[Texasroadrunner]

I had Dellortos, so no direct experience. However:
1) Bigger idle jets might help - they supply the progression holes.
2) My Des Hammill book suggests f15 or f16 emulsion tubes.

I have run several richer Idle jets and it does mask the lean hole mid range quite a bit. The problem is it makes my cruising AFR richer than 11:1 and mileage suffers. I like your Hammill book suggestion for the F16. I'm looking into those too. Thank you.

 

[atomman]

My car had F11's but was leaning out higher up the RPM so changed out to F16s's but then had to go up/down sizes on air correction and mains to get it just right all through the RPM range,

I have one of those plastic organiser tray things now with a loads of spare jets, air corrections and various emulsion tubes gathered from over the years and they come in handy to work through things,

 

[Texasroadrunner]

My car had F11's but was leaning out higher up the RPM so changed out to F16s's but then had to go up/down sizes on air correction and mains to get it just right all through the RPM range,

I have one of those plastic organiser tray things now with a loads of spare jets, air corrections and various emulsion tubes gathered from over the years and they come in handy to work through things,

Greetings Atom, funny you mentioned the plastic organizer box. I just bought one last week for my growing Weber brass collection. They do add up over time. My Weber experience is a little over 3 years. As far as Emulsion tubes go, I am learning all the important stuff. Like, their numbers are in no way sequential from leaner to richer. Oh, heck no, why would Weber do that? I got lucky and met a Porsche Weber expert online months ago. He told me to start soldering the upper air holes and observe the results. I have soldered the top 3 and was about to fill another but I thought I should drive it more before doing that. The Texas weather has recently warmed some from 25F to 65F and that has relieved some of the lean zone problem. It responds better but the widebands still show 16:1 so I will jump in and buy more brass, F16's are in my future. I have plenty of mains and air correctors to counter the change. Other than this lean zone, the car runs great. Crisp throttle response, excellent torque and strong top end. I do appreciate your suggestion to get some F16's. Here's a photo of what my plugs look like. I also ran across an important piece of knowledge lately. What each Etube is sized for in CC's of cylinder displacement. F11=250-325, F15=275-400, F16=350-475, F2=450-575. This find has convinced me to buy a set of F16's. My L24 may just like them. I will post results.

 

[Texasroadrunner]

Weber DCOE 40 Emulsion tube change results. My shiny new F16 E Tubes showed up and I put them in. Went out for a test lap. Nice power with 125 main jets but there is still a leanish mid zone about 3,000 rpm I didn't like. That told me I still had a progression problem. I didn't want to add or drill out any of the 3 progression holes, but it needed more fuel. I put in what I thought was too rich idle jets. From a 50F9 to a 55F9, thinking it would AFR at 11:1 cruising. But nope, it liked it and that stinkin' lean spot disappeared. I also dropped the mains back to a suggested 120 and also 160 air correctors. Much to my surprise and excitement, the performance is spot on along with very acceptable AFR readings as I drive at all throttle openings.
During the week the temperature went from low 40's to mid 70's and the performance was the same. Plugs look tan and clean. Success!

 

[jonbills]

Great result

 

[Texasroadrunner]

Great result

Thanks. My red '72 is way more fun to drive now. Especially in the hard corners. I'm now a DCOE fan for life.

 

[atomman]

Great news

I know DCOE's can be a pain to set up right & most people never get them perfect,

but when there right its great & especially when you do it yourself

 

[Texasroadrunner]

Great news

I know DCOE's can be a pain to set up right & most people never get them perfect,

but when there right its great & especially when you do it yourself

Now that I've conquered my DCOE's a good friend just bought a '74 Triumph TR6. It has some severe problems with the Zenith Stromberg carburetors. Got them all apart and we're making them clean and new. First time for me rebuilding this brand of carb. I hope to get them running well on this nice TR6.

 

[TB24O]

Hi Texasroadrunner, glad you got your triple webers fine tuned eventually, great result and effort to achieve this yourself
Like you said, when you get them set up right they are super
Best regards Tim

 

[Texasroadrunner]

Hi Texasroadrunner, glad you got your triple webers fine tuned eventually, great result and effort to achieve this yourself
Like you said, when you get them set up right they are super
Best regards Tim

Hello Tim, When I first bought my '72 with the DCOE 40's I had no experience with Weber carbs. I was amazed by all of the different circuits and jets involved. The previous owner gave up and let them run rich and poorly. Luckily there are many online sources for learning and parts. It was a long road but worth the journey. I also ordered the longer idle mix screws and springs as you mentioned. Still waiting for them. I recommend Triple Webers to any Z car owners. All my best, Ken

 

[ZeCherman]

Hello guys, I hope I wont spoil the fun and the topic with my question. Ive got 45s Webers 152 on a 2.6 Z. 145 Main Jet and 190 Air correction jet, F16 tube and a 55F8 idle jet. I installed it all and today tried to start it... It runs, kinda Basically what happens is first few seconds are fine and than it starts to cough through the carbs and rpm starts to drop until it cuts out. I guess correctly when I think that I am still way too lean and need to open the needle screw even more? (atm I am at around 2 turns out on a long needle variant)
Again sorry for the off topic question

 

[candy red]

Hello guys, I hope I wont spoil the fun and the topic with my question. Ive got 45s Webers 152 on a 2.6 Z. 145 Main Jet and 190 Air correction jet, F16 tube and a 55F8 idle jet. I installed it all and today tried to start it... It runs, kinda Basically what happens is first few seconds are fine and than it starts to cough through the carbs and rpm starts to drop until it cuts out. I guess correctly when I think that I am still way too lean and need to open the needle screw even more? (atm I am at around 2 turns out on a long needle variant)
Again sorry for the off topic question

Don’t apologise for being off topic as you are on topic it all about Webers and setting up have you checked the plugs after it’s cut out ? I’m no expert but the plugs could be black due to being to rich .Jonbills will be along soon

 

[ZeCherman]

Don’t apologise for being off topic as you are on topic it all about Webers and setting up have you checked the plugs after it’s cut out ? I’m no expert but the plugs could be black due to being to rich .Jonbills will be along soon

I honestly havent because it never even crossed my mind that I am too rich. Definitely not that rich that it chokes the engine until it stalls out at least. Cold engine and lean mixture is my guess but since this is my first time ever coming in real contact with any carbs whatsoever I would gladly soak up anyones knowledge willing to share

 

[Rob Gaskin]

Fuel filter or pipes blocked?

 

[ZeCherman]

Fuel filter or pipes blocked?

Nope, everything is new including the carbs and fuel lines

 

[Texasroadrunner]

Hello guys, I hope I wont spoil the fun and the topic with my question. Ive got 45s Webers 152 on a 2.6 Z. 145 Main Jet and 190 Air correction jet, F16 tube and a 55F8 idle jet. I installed it all and today tried to start it... It runs, kinda Basically what happens is first few seconds are fine and than it starts to cough through the carbs and rpm starts to drop until it cuts out. I guess correctly when I think that I am still way too lean and need to open the needle screw even more? (atm I am at around 2 turns out on a long needle variant)
Again sorry for the off topic question

If you don't have a carb synchronizer you should get one and set all 3 carbs the same flow at idle. Your F16 emulsion tubes are perfect for your cylinder displacement. Your idle jet may be lean and a 55F9 would be better. Idle mix screws shouldn't need to go out more than 2 turns. if you have to adjust needles richer, then that means your idle jets are too lean and you're trying to compensate. 145 Mains might be rich and air correctors pretty close. A wide ban O2 sensor would help tremendously and save you reading the spark plugs so often. For proper jetting you should also know what the choke size is. Webers mean no vacuum advance so your initial timing should be at 16* to 18* plus nearly 35* total advance above 3,000 rpm for clean running.