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Which Webers
- Thread starter Limey
- Start date
alpine_64
Donation Time
Oliver,
A 40DCOE35 is one half of a pair of Holbay webers fitted to the H120/GLS.. The rear carb, the front being a DCOE34 ( later superseded by the DCOE91/92s these carbs arrive LONG after Harrington production and indeed after alpine production.
The DCOE 18s iirc were used on some UK ford twin cam engines as oem and some other small capacity 4 cyl cars in the early 60s
As discussed previously the holbay carbs are unique for their top venting, extended venturis and obviously progression holes.
A 40DCOE35 is one half of a pair of Holbay webers fitted to the H120/GLS.. The rear carb, the front being a DCOE34 ( later superseded by the DCOE91/92s these carbs arrive LONG after Harrington production and indeed after alpine production.
The DCOE 18s iirc were used on some UK ford twin cam engines as oem and some other small capacity 4 cyl cars in the early 60s
As discussed previously the holbay carbs are unique for their top venting, extended venturis and obviously progression holes.
Limey
Donation Time
Thanks Michael. I'm not going the Holbay carb route. I'm after the best type for the engine and with quite a few variables I'm unsure especially choke size. I'm going to educate myself further over the weekend. I've found a massive list of all DCOE with specs and vehicle applications so will try to see if there is a crossover there.
I have a nice period matched pair from a 1600 Alfa Nord that I hope I can use
Cheers
Oliver
I have a nice period matched pair from a 1600 Alfa Nord that I hope I can use
Cheers
Oliver
Attachments
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Limey
Donation Time
Oliver,
Hope you are not intending to put Weber's on your otherwise stock engine.
Hi Bernd,
These are for the Ashley topped project. Hope to do some European touring in her when done. Also It's a bit of a project to build this SII with everything that's in the Special Tuning booklet right down to an LSD and the throttle linkage reinforcement. (Even the back axle baffles tho no one will see them..)
I'm also building a pair of Zeniths on a flowed manifold and matched head so I'll be needing your spindles! I hope to run a poer test to compare the two
bernd_st
Bronze Level Sponsor
Much relieved that they go on your new project. Amazing level of preparation. Wow ! Naturally interested in the tuned Zenith / Weber comparison. Whether it's gonna be the proper setup for relaxed continental touring though is still to be proven, but feel invited to our place anytime...
Limey
Donation Time
It will be only 100bhp or there abouts so not a handful. Enough to keep up with the traffic and climb the alpine passes
alpine_64
Donation Time
Oliver,
30mm chokes will be fine and can give you decent ball park..
Now... I have a theory... And was shared by Jim E (Btw.. For those who are reading this and remember Jim drop him a call amd say hi)
Higher air speed and maybe slightly smaller jets could bring the power and torque back down.
We thought 28mm chokes and maybe 115main with f8 e-tubes and 45f9s could work ( aur correctors would need some fiddling) .. Maybe a little less power but even better throttle repsonse and mpg... At the time 28mm chokes were hens teeth... Now I see a place in Germany on ebay selling fresh chokes in all the odd ball sizes.....
30mm chokes will be fine and can give you decent ball park..
Now... I have a theory... And was shared by Jim E (Btw.. For those who are reading this and remember Jim drop him a call amd say hi)
Higher air speed and maybe slightly smaller jets could bring the power and torque back down.
We thought 28mm chokes and maybe 115main with f8 e-tubes and 45f9s could work ( aur correctors would need some fiddling) .. Maybe a little less power but even better throttle repsonse and mpg... At the time 28mm chokes were hens teeth... Now I see a place in Germany on ebay selling fresh chokes in all the odd ball sizes.....
Limey
Donation Time
I can't pretend I know Webers yet but getting a bit fascinated..Here is a clumsy comparison screen grab of the 'big list' - https://www.carbparts.eu/jetting_table
Nearly all 1600c cars seem to have had 30mm chokes or above except for 2 cars in the list. I'm not jumping to the conclusion that a bigger choke is necessarily the best power option but maybe the best driving compromise for the real world.
I understand that a smaller choke can increase air velocity and therefore the partial vacuum on which the Webers jets and progression holes function most effectively? So sometimes a smaller choke is the key
I'm a sorcerer's apprentice, an sapling compared to you mighty oaks ;-) I'd really appreciate someone putting down their engine and carb specs for newbees like me to learn from.
top - Non vehicle specific factory settings for DCOE 2s, 18s and 32s
middle - My Alfa 44/45s pair
bottom - Holbay
Nearly all 1600c cars seem to have had 30mm chokes or above except for 2 cars in the list. I'm not jumping to the conclusion that a bigger choke is necessarily the best power option but maybe the best driving compromise for the real world.
I understand that a smaller choke can increase air velocity and therefore the partial vacuum on which the Webers jets and progression holes function most effectively? So sometimes a smaller choke is the key
I'm a sorcerer's apprentice, an sapling compared to you mighty oaks ;-) I'd really appreciate someone putting down their engine and carb specs for newbees like me to learn from.
top - Non vehicle specific factory settings for DCOE 2s, 18s and 32s
middle - My Alfa 44/45s pair
bottom - Holbay
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alpine_64
Donation Time
Oliver the holbay jets only work on the holbay motor and with it airbox.. Without the airbox they run super lean.
Years ago and can dig up the thread in the archives we all discussed jetting.. Usa seemed to run fatter jets than uk/ au.
A good kickoff for you will be
30 chokes
F5f9 idle
F16 e-tubes ( these are fat and can blow a little carb smoke but they mask any leaning in transition from idle to main circuit... Recently a friend.. Lance fitted f8 iirc to mine to make it more responsive in intial transition .. Car lost some mid range punch but gained 5mpg on avergae)
120 mains (or 125 or 130 as power / capacity increases )
175-180 air correctors
35 pump jets.
Years ago and can dig up the thread in the archives we all discussed jetting.. Usa seemed to run fatter jets than uk/ au.
A good kickoff for you will be
30 chokes
F5f9 idle
F16 e-tubes ( these are fat and can blow a little carb smoke but they mask any leaning in transition from idle to main circuit... Recently a friend.. Lance fitted f8 iirc to mine to make it more responsive in intial transition .. Car lost some mid range punch but gained 5mpg on avergae)
120 mains (or 125 or 130 as power / capacity increases )
175-180 air correctors
35 pump jets.
Limey
Donation Time
- 40DCOE-2 (14mm pump stroke) (float 8.5mm)
- 40DCOE-4 (14mm pump stroke) (float 8.5mm)
- 40DCOE-8
- 40DCOE-9
- 40DCOE-13
- 40DCOE-14
- 40DCOE-15
- 40DCOE-16
- 40DCOE-18 (10mm pump stroke) (float 8.5mm)
- 40DCOE-19
- 40DCOE-22 (10mm pump stroke) (float 8.5mm)
- 40DCOE-23 (10mm pump stroke) (float 8.5mm)
- 40DCOE-24 (14mm pump stroke) (float 8.5mm)
- 40DCOE-27 (14mm pump stroke) (float 8.5mm)
- 40DCOE-28 (14mm pump stroke) (float 8.5mm)
- 40DCOE-29 (10mm pump stroke) (float 5.0mm)
- 40DCOE-30 (10mm pump stroke) (float 5.0mm)
- 40DCOE-31 (16mm pump stroke) (float 8.5mm)
- 40DCOE-32 (14mm pump stroke) (float 8.5mm)
- 40DCOE-33 (14mm pump stroke) (float 8.5mm)
- 40DCOE-34 ( ) (float 8.5mm)
- 40DCOE-35 ( ) (float 8.5mm)
- 40DCOE-38 (16mm pump stroke)
- 40DCOE-39 (16mm pump stroke)
- 40DCOE-44 ( ) (float 7.0mm)
- 40DCOE-45 ( ) (float 7.0mm)
- 40DCOE-4 (14mm pump stroke) (float 8.5mm)
- 40DCOE-8
- 40DCOE-9
- 40DCOE-13
- 40DCOE-14
- 40DCOE-15
- 40DCOE-16
- 40DCOE-18 (10mm pump stroke) (float 8.5mm)
- 40DCOE-19
- 40DCOE-22 (10mm pump stroke) (float 8.5mm)
- 40DCOE-23 (10mm pump stroke) (float 8.5mm)
- 40DCOE-24 (14mm pump stroke) (float 8.5mm)
- 40DCOE-27 (14mm pump stroke) (float 8.5mm)
- 40DCOE-28 (14mm pump stroke) (float 8.5mm)
- 40DCOE-29 (10mm pump stroke) (float 5.0mm)
- 40DCOE-30 (10mm pump stroke) (float 5.0mm)
- 40DCOE-31 (16mm pump stroke) (float 8.5mm)
- 40DCOE-32 (14mm pump stroke) (float 8.5mm)
- 40DCOE-33 (14mm pump stroke) (float 8.5mm)
- 40DCOE-34 ( ) (float 8.5mm)
- 40DCOE-35 ( ) (float 8.5mm)
- 40DCOE-38 (16mm pump stroke)
- 40DCOE-39 (16mm pump stroke)
- 40DCOE-44 ( ) (float 7.0mm)
- 40DCOE-45 ( ) (float 7.0mm)
bernd_st
Bronze Level Sponsor
Oliver,
you can fiddle around forever with those Webers, but you won't find a real satisfactory setup which gives best performance over the entire range. We have a few guys over here who took it to the max with 2l engines, big valves, etc. but they all ended up at a Weber specialist using a rolling road. Actually they even had to put Lambda sensors into the exhaust tubes in order to come closer to an optimized setup. This goes to far for me, but can check what they actually used...
you can fiddle around forever with those Webers, but you won't find a real satisfactory setup which gives best performance over the entire range. We have a few guys over here who took it to the max with 2l engines, big valves, etc. but they all ended up at a Weber specialist using a rolling road. Actually they even had to put Lambda sensors into the exhaust tubes in order to come closer to an optimized setup. This goes to far for me, but can check what they actually used...
Limey
Donation Time
Hi Bernd - I was never going to tweak these at home. I was always going to leave this to the Weber professionals .You need so many combinations of parts. No, I am sending the new engine and carbs to be bench run and a have safe 'base' tune installed for running in, followed by a final RR session. after 1500mls. Tapping in a lambda sensor per runner is a good idea! might do that.
bernd_st
Bronze Level Sponsor
Oliver, coming back to "the real thing" and your previous modification list:
The 3.5mm Main discharge tube described in the tuning book is the same as they used on the Harrington LeMans in stage 1 tune. Almost unobtainium since there was no other application I'ld know of. It sits between the main jet and the small Venturi tube. Have just pulled a normal one out of a crappy Zenith, but it was nasty to make it come out. Actually had to cut a 4mm thread with a suitable tap same as described in the S2 tuning booklet (pls. see pictures) . Centre bore I measured around 3mm so 3.5mm would give you way more fuel flow. Think it can simply be bored up, but wonder about the matching size of the small side bores. If anybody has more info...
The 3.5mm Main discharge tube described in the tuning book is the same as they used on the Harrington LeMans in stage 1 tune. Almost unobtainium since there was no other application I'ld know of. It sits between the main jet and the small Venturi tube. Have just pulled a normal one out of a crappy Zenith, but it was nasty to make it come out. Actually had to cut a 4mm thread with a suitable tap same as described in the S2 tuning booklet (pls. see pictures) . Centre bore I measured around 3mm so 3.5mm would give you way more fuel flow. Think it can simply be bored up, but wonder about the matching size of the small side bores. If anybody has more info...
Limey
Donation Time
bernd_st
Bronze Level Sponsor
Unfortunately I have never possessed an original Zenith pair from a HLM so can't tell you the size of the side bores. Don't think anybody will pull the discharge tubes out of an original set just to tell us. However since I regard them venting or mixture holes plus they are multiple I'ld assume you can leave them as they are. Yes the central passage can easily be bored up to 3.5 mm...
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