Too rich on my DCOEs
Discussion
Goran - your English is better than mine! I realise that the idle circuit is regulated by the idle jets and mixture screws for each barrel.I have gone for f8 idles jets with bigger air holes than the f9s which were originally in the carbs. This hasn't made much difference, perhaps because of the comparatively small choke size. The current 30mm chokes have not been machined out. The choke size will effect everything and perhaps a lower air flow on tick-over (bigger choke) will also give me a bit more adjustment on my idle screws.
Everything I've read and researched seems to suggest that the 30mm chokes are small for a tuned crossflow and will make the whole circuit richer to the point that if you try and throttle the jets sizes down too much to try and moderate the fuel/air mix then you will just nullify any advantages the
twin side-drafts give over a single twin-choke down-draft.
With regard to the carbs, they are 40DCOE48s which are a bit of a rarity I believe. These are old Italian carbs and do not have the additional air bleed screw fitted to later carbs which I imagine makes life much easier when setting up idle circuit mixture.
I've no reason to think that they are faulty and I had them stripped and cleaned by Southern Carbs. The cam is a Kent 234 which I installed and set up using an adjustable timing gear and crankshaft protractor, using a clock on the piston to measure dwell angle. I spent ages on this and I'm pretty confident I got it right (says I confidently).I am currently running 12 degrees advance at 1000 rpm on an upgraded non vac Alden distributor which came with the Vulcan built engine.
I know a gas analyzer is the kit to have but my thoughts were that I will be able to see if the idle, mid-range and fast running circuit is out by a simple plug test. What I won't know is what the mixture is doing in the progression phase from idle to opening the throttle. If I can get these intermediate stages about right then I'm sure driving the car with the engine under load will tell me if I've got the rest hopelessly wrong!
I have now got a choke/jet/air prescription for the 135 hp Vulcan built engine. I can try this, set up the slow running and carb balance (I have a carb sync vac gadget)and see how she goes. If no improvement I can always go back to the settings I currently have and throw the remaining bits in a bag and go and book a session with a professional. I know this would be the sensible approach and is one I will not hesitate to take if a few simple changes by me bring no improvement.
This process has made me think a lot about how these carbs actually work. They are not as scary as I thought and if nothing else it has enabled me to learn a lot more about how the carb set up impacts on performance and economy. Its all good fun!
Everything I've read and researched seems to suggest that the 30mm chokes are small for a tuned crossflow and will make the whole circuit richer to the point that if you try and throttle the jets sizes down too much to try and moderate the fuel/air mix then you will just nullify any advantages the
twin side-drafts give over a single twin-choke down-draft.
With regard to the carbs, they are 40DCOE48s which are a bit of a rarity I believe. These are old Italian carbs and do not have the additional air bleed screw fitted to later carbs which I imagine makes life much easier when setting up idle circuit mixture.
I've no reason to think that they are faulty and I had them stripped and cleaned by Southern Carbs. The cam is a Kent 234 which I installed and set up using an adjustable timing gear and crankshaft protractor, using a clock on the piston to measure dwell angle. I spent ages on this and I'm pretty confident I got it right (says I confidently).I am currently running 12 degrees advance at 1000 rpm on an upgraded non vac Alden distributor which came with the Vulcan built engine.
I know a gas analyzer is the kit to have but my thoughts were that I will be able to see if the idle, mid-range and fast running circuit is out by a simple plug test. What I won't know is what the mixture is doing in the progression phase from idle to opening the throttle. If I can get these intermediate stages about right then I'm sure driving the car with the engine under load will tell me if I've got the rest hopelessly wrong!
I have now got a choke/jet/air prescription for the 135 hp Vulcan built engine. I can try this, set up the slow running and carb balance (I have a carb sync vac gadget)and see how she goes. If no improvement I can always go back to the settings I currently have and throw the remaining bits in a bag and go and book a session with a professional. I know this would be the sensible approach and is one I will not hesitate to take if a few simple changes by me bring no improvement.
This process has made me think a lot about how these carbs actually work. They are not as scary as I thought and if nothing else it has enabled me to learn a lot more about how the carb set up impacts on performance and economy. Its all good fun!
Not having air mixture screws must make things a lot more difficult! I have not worked with such carbs. Picking the right idle jet becomes crucial.
I had a look at Misab's web page (a company well known for selling weber carb kits and their own Weber/Dellorto intakes). They suggested the following setup for a "tuned" 1600 X-flow (whatever that is):
Chokes 30
Mains 115
Air corrector 200
Idle jet 45F8
E-tube F11
Acc pump jet 40
Pump exhaust valve 50
Float level 7mm
I had a look at Misab's web page (a company well known for selling weber carb kits and their own Weber/Dellorto intakes). They suggested the following setup for a "tuned" 1600 X-flow (whatever that is):
Chokes 30
Mains 115
Air corrector 200
Idle jet 45F8
E-tube F11
Acc pump jet 40
Pump exhaust valve 50
Float level 7mm
Grantura SWE said:
Not having air mixture screws must make things a lot more difficult! I have not worked with such carbs. Picking the right idle jet becomes crucial.
I had a look at Misab's web page (a company well known for selling weber carb kits and their own Weber/Dellorto intakes). They suggested the following setup for a "tuned" 1600 X-flow (whatever that is):
Chokes 30
Mains 115
Air corrector 200
Idle jet 45F8
E-tube F11
Acc pump jet 40
Pump exhaust valve 50
Float level 7mm
Nice one, Goran ! Unfortunately Misab site is swedish only, could you dig up similar stats for a 38DGAS, stages II, kent V63 please ?I had a look at Misab's web page (a company well known for selling weber carb kits and their own Weber/Dellorto intakes). They suggested the following setup for a "tuned" 1600 X-flow (whatever that is):
Chokes 30
Mains 115
Air corrector 200
Idle jet 45F8
E-tube F11
Acc pump jet 40
Pump exhaust valve 50
Float level 7mm
@OP; sorry for going off topic..
No worries Frank. Thanks Goran, that set up is almost identical to mine except the F11 tubes. My carbs do have an idle mixture screw per barrel but that only regulates the amount of premixed flow into the head on the idle circuit. I think the 151s have an addition air bleed screw which can be used to lean off the mixture.
If my memory serves me right F11 give you a richer bottom end (of the main circuit) compared F16. This also mean s that F16 gives a shorter transition period where the primary circuit overlaps with the main circuit and hence the very top end of the primary circuit will also end up leaner. I don’t think that F11 would solve your problem. But I may remember incorrectly... I’m sure you can find out the characteristics if you google the E-tubes. If not just looking at a picture of them tells you a lot.
Too bad you don’t have access to a wideband lambda meter. It shows exactly when the engine runs lean or rich and also how much. It even gives you the opportunity to plug single holes in the E-jets and test how it affects the performance.
Anyway, to me it sounds strange that you would need smaller idle jets than 45. You should be able to tune with the idle mixture screws. So the question is if fuel leaks in from elsewhere (as others have already suggested).
-Is the fuel pressure correct?
-Have you checked the float level (it has a big influence in how the E-tubes function)?
-Can you see any evidence of the engine being more or less rich/lean on any cylinder?
bluezeeland,
Misab only has two suggestions for 38DGAS fitted to Ford engines. No mention of if or how the engine is supposed to be tuned or any other spec.:
2300 V6, 38 DGAS
Chokes 27
Mains 135
E-tube F50
Air corrector 190
Idle jet 50
Acc pump jet 70
Pump exhaust valve 30
2800 V6, 38 DGAS
Chokes 27
Mains 142
E-tube F50
Air corrector 185
Idle jet 55
Acc pump jet 70
Pump exhaust valve 30
You can find the complete list at http://www.misab.se/bestyckn.php?kid=4-140-172
Then it is just up to you to learn Swedish and to figure out what a "huvudmunstycke" (main jet) or "halsring" (choke) is
Too bad you don’t have access to a wideband lambda meter. It shows exactly when the engine runs lean or rich and also how much. It even gives you the opportunity to plug single holes in the E-jets and test how it affects the performance.
Anyway, to me it sounds strange that you would need smaller idle jets than 45. You should be able to tune with the idle mixture screws. So the question is if fuel leaks in from elsewhere (as others have already suggested).
-Is the fuel pressure correct?
-Have you checked the float level (it has a big influence in how the E-tubes function)?
-Can you see any evidence of the engine being more or less rich/lean on any cylinder?
bluezeeland,
Misab only has two suggestions for 38DGAS fitted to Ford engines. No mention of if or how the engine is supposed to be tuned or any other spec.:
2300 V6, 38 DGAS
Chokes 27
Mains 135
E-tube F50
Air corrector 190
Idle jet 50
Acc pump jet 70
Pump exhaust valve 30
2800 V6, 38 DGAS
Chokes 27
Mains 142
E-tube F50
Air corrector 185
Idle jet 55
Acc pump jet 70
Pump exhaust valve 30
You can find the complete list at http://www.misab.se/bestyckn.php?kid=4-140-172
Then it is just up to you to learn Swedish and to figure out what a "huvudmunstycke" (main jet) or "halsring" (choke) is
Cheers Goran,
How does the float level influence the emulsion tubes ?
the figures for the 2300 are more or less the stats as per original in a standard essex (bar the idles, 43 iso 50)
the figures for the 2800 are closer to what i've got (main 150 iso 142 and air 195 iso 185)
Will have a play (next weekend only.....need spare time, time)
regarding learning swedish, it would come in handy when 'communicating' with curvey blondes, and knowing your 'main jet' is helpful too !
txs !
Frank
How does the float level influence the emulsion tubes ?
the figures for the 2300 are more or less the stats as per original in a standard essex (bar the idles, 43 iso 50)
the figures for the 2800 are closer to what i've got (main 150 iso 142 and air 195 iso 185)
Will have a play (next weekend only.....need spare time, time)
regarding learning swedish, it would come in handy when 'communicating' with curvey blondes, and knowing your 'main jet' is helpful too !
txs !
Frank
Edited by bluezeeland on Friday 22 August 12:48
Many moons ago, we got a lot of value from using a Gunson Colortune on a mini that we were "experimenting" with. Might be worth a try if more exotic equipment isn't readily available.
cheers
Nick
cheers
Nick
The function of the E-tubes is that fuel and air is sucked in through the holes on the tube. Different tubes have different numbers, sizes and shapes of holes at various positions along the tube. The tube sits in a recess in the carb that is filled with fuel to a certain level. Depending on float level, load, throttle and other variables the level changes and hence the fuel mixture varies. If the float level is different to what is intended when the tube was designed it has the same effect as if the holes were drilled in a different height on the tube.
As some of the tubes are quite different I’m sure the effect of the fuel level differs between the types. Some are more sensitive and others are less.
There used to be a video somewhere on the net that showed the function of the E-tube really well. Some guy had made a mock-up of a part of a Weber carb in transparent plastics and fitted an E-tube in it. It was connected to the engine in his car and he filmed the setup as he was driving at various loads and revs. Very interesting and educational to see.
I have not been able to find the video now. I think it was a British site and the guy had an Elan…..
In my experience there are lots of blonds interested in guy with foreign accent when visiting nightclubs in Sweden. The one of my foreign friends who turned out to be of most interest was actually from Birmingham with a distinct Brummie accent. I’m not sure that the girls that fancied him understood a single word of what he said.
As some of the tubes are quite different I’m sure the effect of the fuel level differs between the types. Some are more sensitive and others are less.
There used to be a video somewhere on the net that showed the function of the E-tube really well. Some guy had made a mock-up of a part of a Weber carb in transparent plastics and fitted an E-tube in it. It was connected to the engine in his car and he filmed the setup as he was driving at various loads and revs. Very interesting and educational to see.
I have not been able to find the video now. I think it was a British site and the guy had an Elan…..
In my experience there are lots of blonds interested in guy with foreign accent when visiting nightclubs in Sweden. The one of my foreign friends who turned out to be of most interest was actually from Birmingham with a distinct Brummie accent. I’m not sure that the girls that fancied him understood a single word of what he said.
Only goes to show that carburettors are a clever bit of engineering.
Obviously it is clear what a carb does, but how this all comes together is another matter.
I did not know about the levelling of the fuel in the emulsion tubes, and acting as a regulator.
Sort of guessing the 38DGAS is less susceptible to minor changes in float-level than a 40DCOE ? (which does make Andy' 'problem shooting' somewhat easier....or the r/r operator...)
Regarding accents & girls; you need to speak the language of 'love'
Obviously it is clear what a carb does, but how this all comes together is another matter.
I did not know about the levelling of the fuel in the emulsion tubes, and acting as a regulator.
Sort of guessing the 38DGAS is less susceptible to minor changes in float-level than a 40DCOE ? (which does make Andy' 'problem shooting' somewhat easier....or the r/r operator...)
Regarding accents & girls; you need to speak the language of 'love'
Edited by bluezeeland on Friday 22 August 19:48
This might be lost on you guys but I'm working on my Noddy Holder accent before booking my next holiday to Sweden!
Although I haven't got a wide band lambda sensor I do have an old Gunsons colour tune so I'm going to have a play with my idle circuit once the sun dips down! Thanks again for all the helpful suggestions. This forum is a very good place for info. Long may it be so.
Although I haven't got a wide band lambda sensor I do have an old Gunsons colour tune so I'm going to have a play with my idle circuit once the sun dips down! Thanks again for all the helpful suggestions. This forum is a very good place for info. Long may it be so.
Cerberus90 said:
bluezeeland said:
Only goes to show that carburettors are a clever bit of engineering.
Obviously it is clear what a carb does, but how this all comes together is another matter.
It's Magic is what it is. Obviously it is clear what a carb does, but how this all comes together is another matter.
tomtrout said:
Thanks guys, lots to think about. The Aux chokes are 4.5s I think.
I know the original downdraft twin choke carb was always going to be less of a headache but my car came with the twin 40s and I rather like the sound and the look as well as that little extra punch. Not quite so keen on the mpg!
Obviously I cant give you any help Andy as setting up carbs etc I leave to the experts as you know but I cant help wondering if you keep throwing time and money at these ones and in the long run do damage to the engine as I know that can happen if set up wrong done that got the rebuild bill.I know the original downdraft twin choke carb was always going to be less of a headache but my car came with the twin 40s and I rather like the sound and the look as well as that little extra punch. Not quite so keen on the mpg!
I Think I might bight the bullet take to a rolling road and ask them to supply and fit a new set of twin 40s that can be adjusted easier and then if they are not right you can go back and its there baby to sort I understand the desire and challenge of doing it all yourself but sometimes it can be a false economy.
Then sell on the ones you take off as you say they are rare so someone somewhere will value them.
When I re built my top end with unleaded heads and new pistons and rings I took all the speck to the Engine builder highly recommended who actually does most of burtons engineering work and he looked at the build speck for the engine and identified the problem the settings that the company had done in Germany after it went there had caused the damage one thing that amazed me and a local mechanic was the timing advance at idle it was 18 I think would have to check the file not 12 which amazed me but when I went to the tuners they agreed.
Just a Thought sorry I cant give you more advice like the real experts on here.
A
Rather than editing the above I went and got the file with all the figures and I was wrong on the advance at idle as you can see
I am unsure how this compares to you engine spec Andy but may be of help
Bore 83.271mm
stroke 77.62mm
capacity 1690cc
Compression ratio 10:6:1
Pistons +0.090 hepolite (balanced and modified)
Camshaft Kent 244
Crankshaft Balanced Ground 20/20
Rods Lightened and balanced
Flywheel ligthened and balanced
Twin 40 DCOE Carbs
Valve Clearances inlets 22 exhaust 24
timing 13% at tick over 32% at 3000rpm
Maybe this is of help I really don't know she 128bhp at 110mph at 4893rpm in 4th gear as he had not realised there was a fifth or maybe they don't test in 5th as its an overdrive I am told she red lines at 6000rpm with that set up but I don't plan on testing to be honest.
A
I am unsure how this compares to you engine spec Andy but may be of help
Bore 83.271mm
stroke 77.62mm
capacity 1690cc
Compression ratio 10:6:1
Pistons +0.090 hepolite (balanced and modified)
Camshaft Kent 244
Crankshaft Balanced Ground 20/20
Rods Lightened and balanced
Flywheel ligthened and balanced
Twin 40 DCOE Carbs
Valve Clearances inlets 22 exhaust 24
timing 13% at tick over 32% at 3000rpm
Maybe this is of help I really don't know she 128bhp at 110mph at 4893rpm in 4th gear as he had not realised there was a fifth or maybe they don't test in 5th as its an overdrive I am told she red lines at 6000rpm with that set up but I don't plan on testing to be honest.
A
Grantura SWE said:
My oh my....
Irish also seem to work quite well. Tullamore accent to be exact. Good luck guys!
If you ever visit Gothenburg let me know. It might be good entertainment!
cheers Goran, Irish also seem to work quite well. Tullamore accent to be exact. Good luck guys!
If you ever visit Gothenburg let me know. It might be good entertainment!
Ignoring the irish bit........
Visiting Gothenburg accepted !! (could be a right laugh, and...we might learn a thing or two, about carbs....obviously....)
Frank
Edited by bluezeeland on Friday 22 August 20:20
Grantura SWE said:
My oh my....
Irish also seem to work quite well. Tullamore accent to be exact. Good luck guys!
I am actually Mountmellick but only 14 miles from Tullamore a great area to take your car if you get a change and a drive through the Cut the Sleeve Bloom mountains is a must not done it yet as not taken and of the TVRs over yet but on my Bucket list I did do the run many years ago in the snow though in a rather rare Avenger Tiger if only we knew we would still have it in the family.Irish also seem to work quite well. Tullamore accent to be exact. Good luck guys!
A
Edited by prideaux on Friday 22 August 20:22
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