13 replies to this topic

[CDCJ]

Hi all,

Does any one know about weber carburetors especially 40DCOE?
Many variations exist in 40DCOE type with a long manufacture period.
40DCOE 2,4,18,24,27 ,31,33..........................151.....?
for example, What's different between 40DCOE2 and 40DCOE18?
Of course, the original equipment jet setting is different by each cars.
What's the body or part different between 40DCOE2 and 40DCOE18?
Probably the 40DCOE18 has improved from 40DCOE2? or just different start production year?
Please give me your advice and let me know the specialist.

I'm looking for some information about weber carburetors.
I very much appreciate your cooperation.

Kind regards,
Hiro

[oldtransamdriver]

Try Overseas Auto in Vancouver B.C. They are Weber distributors. Contact Jim Hilton - former racer who is very knowledgeable about these carbs.

Robert Barg

[SJ Lambert]

These guys are very knowledgeable as far as all sidedraft Webers are concerned.

http://autos.groups....edraft_central/

Hours of fun researching!!

They may well say that type 40 DCOE 18s are quite similar to a number of others. There may have originally been different lengths of accelerator pump rod travel for some and other minor variations, but most types of a similar age (especially those that pre-date "emission carbs") may well have the same bodies and be able to be set up as desired.

I've tried to see whether there are any fundamental differences between different designations of type 45 DCOEs of the same vintage, I haven't discovered any major differences from differing types of the same age from the sixties.

Cheers

James

Edited by SJ Lambert, 11 February 2012 - 08:58.

[CDCJ]

Thank you very much for your inputs.
The Weber carburetor is confusing me.
Even the same carburetor(eg: 40DCOE2) has different the jetting for each cars.
What had they distinguished by the number?
Maybe the serial number? Do you know the rule of the serial number?
Some one all digit and other one alphabet+digit.
Do you know when 40DCOE2 and 40DCOE18 production began?
I very much appreciate your cooperation.
Kind regards,
Hiro

[Nick Wa]

Both jets and choke tubes were changeable items to suit a particular engine (I had 3 different engines but only a pair of 40s so I changed bits on a regular basis). So I don't think the numbering is anything to with it.
I'll hazard a guess that these trailing number are a quality control thing and refer to the moulds the castings originate from.

Edited by Nick Wa, 12 February 2012 - 17:27.

[JtP1]

More interested in 45s personally, but the difference in their suffix numbers is usually to do with the tickover drillings to match particular engines. Ie, siamized or single inlet tracts.

[hillsprint]

Some of the differences are in the throttle transition hole pattern and hole size to suit different engine styles. If I recall correctly, they deal with the initial throttle butterfly movement from idle, and can be found under the brass blanking plug just in front of the idle mixture screw above each butterfly.

[CDCJ]

Thank you again for your inputs.
The tickover drillings and the throttle transition hole pattern means "progression" holes?
40DCOE2 and 40DCOE18 has the "progression" holes and do place the progression holes in different places?
Please let me know. Does anyone has some photos?
Thank you.
Hiro

[cheapracer]

I know one thing for sure, when you find a choke loose in one of your 40's, don't be surprised when a few months later you take the head off to find a perfect imprint of the choke's retaining spring in the top of your piston ;) - 40's were buggers for doing that.

As people suggest, the model numbers were for different manufacturers/engine series requiring different idle and progression curves.

Good luck understanding Weber's numerical systems, no one else ever did.

[CDCJ]

I will try to get the information about Weber's numerical systems.
Yes, It seems no one else ever did.
Maybe currently owned by Magneti Marelli has the information?
or is there some one Italian specialist?
All original equipment jet setting for 40DCOE（2/18） is changeable.
The unchangeable part for 40DCOE（2/18） only the progression" holes and do place the progression holes in different places?
and the other body parts is same?
Thank you.
Hiro

[PS30-SB]

All original equipment jet setting for 40DCOE（2/18） is changeable.
The unchangeable part for 40DCOE（2/18） only the progression" holes and do place the progression holes in different places?
and the other body parts is same?

Hiro,

Be careful of the difference in ACCELERATOR PUMP STROKE between 40DCOE-2 and 40DCOE-18.

40DCOE-2 had 14mm accelerator pump stroke, and 40DCOE-18 had 10mm accelerator pump stroke. So, 40DCOE-2 pump rod is longer than 40DCOE-18 pump rod.

Pump rod length is quite an important factor in tuned engine 'driveability'...




Is this for a Lotus T/C?

[CDCJ]

Many thanks for the information.
I think the acceleration pump stroke is changeable too.
However the original equipment must be always 40DCOE-2 had 14mm and 40DCOE-18 had 10mm, right?
also I think the original equipment ET must be always 40DCOE-2 had F16 and 40DCOE-18 had F11?
Yes! my interest is Lotus T/C especially. (Please find my Lotus TC topic on the forum)
My question began, early(1963) Lotus Elan and Lotus Cortina had 40DCOE-2. But it have changed to 40DCOE-18 late 1963 or early 1964. The Lotus TC specification must be same at that time. Why it change for?
Maybe 40DCOE-2 end of production in 1963? or something improved with 40DCOE-18?
I very much appreciate your inputs.
Kind regards,
Hiro

[PS30-SB]

I think the acceleration pump stroke is changeable too.

Yes, that's true. You just change the pump rod.

However the original equipment must be always 40DCOE-2 had 14mm and 40DCOE-18 had 10mm, right?

Yes, that's the way that Weber supplied them 'in the box' / 'off the shelf' ( and therefore presumably on a 'standard equipment' fitment like a Lotus T/C, according to Weber's own data ).

...also I think the original equipment ET must be always 40DCOE-2 had F16 and 40DCOE-18 had F11?

Yes, that's what I see in the Weber data I have. This was true for the 40DCOE-2 and 40DCOE-18 when they were fitted to other makes & models as 'standard equipment', such as certain Alfa Romeos, Abarths etc.

My question began, early(1963) Lotus Elan and Lotus Cortina had 40DCOE-2. But it have changed to 40DCOE-18 late 1963 or early 1964. The Lotus TC specification must be same at that time. Why it change for?
Maybe 40DCOE-2 end of production in 1963? or something improved with 40DCOE-18?

My guess ( and it's just a guess ) is that the 40DCOE-18 was a better-matching 'off the shelf' version of DCOE - as supplied by Weber to Lotus - for the T/C engines in question. Maybe to do with that accelerator pump rod stroke, and the F11 emulsion tubes? The 18 might have given better 'driveability' over the 2 for road-going cars. Certainly the 2 and the 18 were both in production by Weber long into the 1970s, so I don't think there was any question of one superseding the other. I'll bet it was something to do with keeping customers satisfied with their experience in using the cars on a day-to-day basis. Possibly something as small as an occasional 'gasp' in certain conditions. The answer is probably more simple than we might imagine...!



If you need any early 40DCOE-2 or 40DCOE-18 spares, let me know. I might have some useful bits and pieces.

[CDCJ]

Hi Alan,
Thank you very much indeed your reply.
Yes, The answer is probably more simple than we might imagine.
However the 40DCOE-2 and 40DCOE-18 when they were fitted to other makes & models as 'standard equipment' as you know.
How did they(Weber) manage the carburetors for other makes & models? Maybe the serial number?
Does someone have Weber's production chronology?
Probably they had 40DCOE31 for Lotus TC in 1970's.
Same again, What's different? something improved?
I'm very interested early 40DCOE-18 spares for my study. I will send PM.
Thank you again for your help.
Kindest regards,
Hiro