MatraSport Forum

Hi all

Using the new feature of the forum, I have started a blog about my Weber DCOE carburettor conversion project.

A blog is a personal thing and as such ideal for sharing a project while it's happening. I'll try to amend to the blog whenever I have something to share or document, but I can't promise any specific frequency.

Feel free to comment! - I'm the "blog owner" and the only one who can post in the blog, but everyone can post their opinions, comments, questions etc.

Here's a direct link to the blog:

http://www.matrasport.dk/forum/index.php?action=blog;blog=25

I hope you'll enjoy it! :)

- Anders

I've posted a new message on the Weber blog. I now have the carburettors on the manifold, ready for initial testing on the car :)

http://www.matrasport.dk/forum/index.php?action=blog;blog=25

Since last post here, I've posted two new blog entries in my Weber blog...

Here's the latest:
http://www.matrasport.dk/forum/index.php?action=blog;blog=25;entry=1166

The carbs went on the engine today! ;D Still a bit more work to do before I can fire it up, but at least they are now where they are supposed to be instead of collecting dust in my basement!

http://www.matrasport.dk/forum/index.php?action=blog;blog=25;entry=1177

I fixed the dipstick tonight. I had to take the carbs off, but they are back on now. Read here:

http://www.matrasport.dk/forum/index.php?action=blog;blog=25;entry=1179

It's alive! It runs!

Idle is too low, it's too lean in the low end (I think, haven't checked anything yet, but it spits back a bit and hestitates) and I have a valve clicking like mad (I haven't noticed it before?), but they seem balanced and the sound is great! "HrrrrrRRRRRRRRRRrmmmmmmm"

More later...

I took this photo last night after the throttle cable was done:

(http://gallery.dinsen.net/d/11071-2/DSC_1395.JPG)

The blog is now updated :)
http://www.matrasport.dk/forum/index.php?action=blog;blog=25;entry=1186

A few more adjustments and a resource list in case you wan't to know more about carburettor tuning...
http://www.matrasport.dk/forum/index.php?action=blog;blog=25;entry=1194

And once again an update about "tuning progress" with the Webers:
http://www.matrasport.dk/forum/index.php/topic,1217.0.html

This morning, I have contributed with an update about trying the larger acceleration pump jets, and experiments with airbox design :) :

http://www.matrasport.dk/forum/index.php/topic,1223.0.html (http://www.matrasport.dk/forum/index.php/topic,1223.0.html)

Just did a quick airbox for you Anders.  ;D

Trying to brush up on my drawing skills.
Just say what more you want on it, and I'll see what I can do. 8)

Niiiiice :)

You've mirrored it though... or extruded it the wrong way ;)

I can send you my latest drawing later in DXF (I'm awaiting a delivery of a mounting flange to complete it), but without the complete engine room and engine mapped up, there's not really any reason to make a 3D model. Cardboard and plywood has worked fine for my prototyping... and my 2D drawings of the hole patterns are enough to weld up a box.

But I might have triggered you here... I've got a few drawings of the carbs that you can use to create a model of those...? :)

- Anders

Just pass'em along Anders  ;)

hmm thats solid works right and not ProE ?

will there be a cold airduct for fresh air to that filterbox?

Indeed. The inlet hose will be connected on the side and air will be fed through the original filter assembly.

- Anders

Sry Oskar, none of the above...  :D

Used Inventor 2009(the best IMO), but I also have SolidWorks2009 if I ever need it. Have also installed Autodesk Alias Studio for schetching, and Autodesk Showcase for digital prototyping.


Anders, can you mail me the drawings and I'll see what I can make of them.

Just fiddled a little around today with your drawings and pics Anders....

:D That's easy to recognise as a genuine Weber 40DCOE - with a few parts missing! Well done!

Modeled some more....

It's great to have friends!

My car decided to give up tonight. I don't know why yet. The first sign of problems was friday afternoon when it stalled on the way back from work. It's a very short drive, only 2 km, so it was cold and I thought it was just the cold running problems I had experienced before. Friday evening, I switched the fuel pump to one that's supplying the correct pressure. That shouldn't have any effect (the carbs coped with the higher pressure), and now, Sunday evening, I was to drive out to Frederik Moes to give him the final drawings of the airbox so he can weld it up for me.

To make a long story short, I stranded completely about 2 km from home. One hour later, Frederik had towed me back and the car is now sitting in its usual location.

I'm very close to scratch it all and refit the good old Solex carb, but I'll withstand the urge an find out what's wrong. I think I'll have to take the carbs off and inspect everything. It could be almost anything: Dirt, broken manifold gasket, starting system leaking...

Symptoms are starting problems, idle mixture jets seems to have little or no effect, it can idle, but dies after being rev'ed up a little, and the popup headlights almost didn't work - or worked only very slowly.

I'm puzzled. And a bit annoyed.

Thanks for helping me, Frederik :)

Get a diesel :P

Well seriously I'm sorry to hear about your problems... I don't have any thing clever to suggest.

You behave yourself, now young man! Last time I saw your car, it didn't even have an engine inside! ;D  :P  :P

I think I'll know later today...

My suspicion about air leak was correct. I have to admit, that I cut a corner when I assembled the carbs over summer:
One of the O-rings to fit in the spacers between the carbs and manifold were missing. I sealed it with silicone instead  :-[ With the carbs and manifold off the car, I could see that a bit of it had been sucked in. Depending on temperature, it was probably allowing quite a bit of air to pass through all around. This was on the same cylinder where the vacuum takeoff for the headlight system, which explains why I coulnd't raise the headlights last night - it was simply not producing enough vacuum.

Fortunately I ordered a set of new O-rings with my last order from Fastroadcars - and I can see now that I should have replaced them from the beginning. The new O-rings give better spring function, which is essential to prevent fuel frothing in the float chamber.

I actually noticed last night, that fuel in the right hand carb was indeed frothing. This was visible when I took the inspection lid off. The other one was fine.

Now that I had the carbs off the engine anyway, I thought I could just as well move the linkage to the underside as I had planned. It took a bit of fiddeling to get it right, but finally it worked. I thought! Because when I had the whole assembly fitted on the engine, I wanted to give it a last check by one complete push on the pedal - BUT IT COULD ONLY MOVE HALFWAY!

It turns out that the connecting rod on the linkage hits the manifold, so the throttle can't open fully :( It looks good to have the linkage on the underside, but there's not much fun if I can ever only run 2/3's of full throttle!!

I got quite pi.... off when I realised this, but I'm better now :) I "only" need to take the manifold and carbs off ONCE MORE  and move the linkage... "only" two hours of work or so fiddeling with the nuts on the underside of the manifold  >:(

By the way: I managed to get the carbs aligned better this time, so I think the syncronisation problem will be fixed :)

- Anders

Thats what I did!!... and it uses exactly HALF ( Fact!) as much fuel as the Murena....
.. However I must admit that it also takes TWICE (not a fact) as long to get anywhere  ;D

So now you only need to combine your two cars  ;)

I've posted an update on the blog:
http://www.matrasport.dk/forum/index.php?action=blog;blog=25

Here's how the system currently looks:

(http://gallery.dinsen.net/d/11674-2/DSC_3210.JPG)

Yes, it looks good... but runs like hxll :( Read the blog for details ;)

Hi Anders

Having raced a number of cars running twin 40 Weber and Dellorto set ups including rear engined Simca derivatives, I would strongly recommend having the carburettors set up on a rolling road; not only will this you the optimum mixture across the rev range but will also check the mechanical advance/retard mechanism in the distributor and also the timing can be tweaked if required. They would also check the ignition system in general.

When using a standard single throttle cable you could remove one of the return springs, this will reduce the load required to open the throttle and prolong the throttle cable life. To counteract the extra load on the rear engine race car where I had to use both return springs, I used to make a throttle cable using motor cycle brake cable which was more than capable of taking the load

Regards
John

PS. Sorry if this has already been suggested.

Hi John

Thanks for sharing your experience! It's much appreciated :)

I ran with only one return spring for some time, but last time I refitted the carbs, the single spring didn't return the spindle to the idle stop, so I fitted the other one too. Thinking about it again now, it shouldn't be necessary as the engine vacuum will make sure that the throttle remains closed when the engine is running. The pedal is quite stiff, but it actually does not feel much different with one or two springs.

The idea of using motorcycle brake cable is very good!

We don't have that many engine tuners with rolling roads and knowledge of carbs here in Denmark. I think the situation is much better in England. The guy who tested Lennart's Murena back in 2004 (?) has been recommended by a few people, but lives some 80 km from me, so in any case, I would either have to refit the old carb before going, or make sure the new carbs are well enough to do the jurney.

Fortunately I think I may have solved my problem: I replaced the ignition coil yesterday evening (it was the only component I hadn't attended to), and much to my delight, the car sprung to life very easily!

Checking the old coil, it turned out to have a secondary resistance of 6000 Ohm, which indicates that it has been burnt inside. It's only two years old, and it has never run "open ended", so why it has failed remains a mystery. It was probably the wrong coil, though, since it had "ballast" written on it, but with a primary resistance of 1.2 Ohm and electronic (current limited) ignition to drive it, it should have been able to take the load anyway. It didn't, however, and it has now been replaced with an old Bosch coil which I salvaged from Waldo's car in July, and which I had lying around.

I sweared a lot over the engineer who decided on the location of the coil on the 2.2: It's hopelessly inaccessible! And the right side of the engine room is probably the wettest place in the engine room with the alternator's fan throwing water around just next to it  ::)

- Anders

I concur... that part of the engine bay gets completely soaked in the wet... hopeless place to fit the electrics.. but  hey... it's French .. ;D

Problem is indeed solved, and never has the configuration run this well. Hot, cold - it just pulls nicely from 2000 rpm and up and fires up easily. I have a flat spot around 1500 rpm, but nothing bad, so this might be the right time to go on the rolling road. Still, I have to gain some confidence in the setup, but the running problems are history now! and I'm very happy :D

- Anders

It's great to hear that the Green 2.2 didn't go to waste for nothing  ;)

Great looking job by the way Anders...

Oh yes, that would have been a pity if it did. I'm using it's engine loom to make a new one, the thermostat housing is the one I have running now, the distributor has been restored and will go on my car eventually, and the spring cups I have on my rear end comes from that (as you know, Valdemar!)


Thanks. I too am quite satisfied with the look, and it performs quite well too: I took it out for a spin this morning (to work), and boy what an acceleration and SOUND in 3rd from 2500 to 5500 or so... ;D

Second stage progression isn't good though, but the new ignition coil does wonders to overcome it. The cure could be to go down to 34 mm venturis, but they aren't cheap so I have to try a few other things first. Also, it's loosing fuel in the float chambers over time - the level drops some 5 mm when the car is standing. I think the fuel seeps out of the acceleration pump jet? This is probably due to the 15 degree inclination of the carbs, which is 10 more than Weber recommends, and with the way the starting system and accel pump is made on these carbs, it can cause problems. In hindsight, I think Dellortos could have been better in this respect?

I'm not optimistic about the project though - the Espace has hit us hard with the timing belt change, which due to ridiculous prices on spare parts and a lot of faults discovered in the process will cost us a fortune, so I will probably have a difficult time negotiating funds with my wife... :( Shelving the DCOE's and converting back could be a possibility, at least for a period...

I have a pair of 40mm's I'm not using, if you want to experiment :)

THANKS, I really appreciate that :D

I'll keep it in mind. But I'll look more carefully into the problem and discuss it with knowing people before I do anything. And it has worked for others... (thinking...)

Just tried a new idle jet - and result is very good. Blog is updated:
http://www.matrasport.dk/forum/index.php?action=blog;blog=25

I've written two entries since last pointer here:

One with a photo of the internals of the failed coil:
http://www.matrasport.dk/forum/index.php?action=blog;blog=25;entry=1287

And today's with a status update:
http://www.matrasport.dk/forum/index.php?action=blog;blog=25;entry=1289

Sounds like I should get myself a set of DCOEs and ship them to Dk for some love, care and adjustment...  ;) hehe

Gentlemen, there's a new post on my Weber blog, if you're interested.

http://www.matrasport.dk/forum/index.php?action=blog;blog=25;entry=1322

How much did you have to pay for the Webers? I come across some(new perhaps since it was a tuning companys ad) in a norwegian car magazine, at the price of 3100,- NOK(387euros) for each. Will try to find them again, and see what more I can dig up on them.

I have diagnosed the "carburettor ice" problem - it was not ice at all, but a failing component. Krede in particular will enjoy reading this latest blog entry:
http://www.matrasport.dk/forum/index.php?action=blog;blog=25;entry=1334



That sounds okay for a new carburettor. I buy parts from this company: http://www.fastroadcars.co.uk and he sells a new 40DCOE carb for 257 GBP (2625 NOK). Mine are old, though, probably even older than my car, so I got them considerably cheaper than that (and in fact didn't "pay" them with real money - I swapped them with Hans for a good cylinder head). I've had to spend a fair amount on parts, so in the end it may turn out to be not much cheaper than a set of new carbs.

Webers are generally expensive, and not better than Dellortos, so I actually suggest you go for a set of those instead. They can be found rather cheap on eBay, and don't worry about buying a used set because they are usually easy to clean and get back in shape. Parts for Dellortos are available from http://www.dellorto.co.uk/

But don't forget that you need a good manifold. A manifold is a very critical component! Simon lists a reproduction Murena S-manifold in his catalogue, but you should check with him if he has them in stock or not. Also, I don't feel that my (reproduced) manifold is quite up to standard, so you might want to check the work before you start your project. For example, the fixing studs for the carburettors were not perfectly in line, as they need to be to achieve good syncronisation between the carbs.

And the absolutly first thing you would want to do is buy some of the books I mention here:
http://www.matrasport.dk/forum/index.php?action=blog;blog=25;entry=1194

- Anders

You can get a set of used ones for much less than that on ebay.

I think they usually turn out too expensive in the end of the auction, though the 40's are usually considerably cheaper than the 45's. You'll get more value for your money with Dellorto's on eBay.

- Anders

I have posted a brief update about the rolling road session in the blog:
http://www.matrasport.dk/forum/index.php/topic,1499.0.html

And another update today:
http://www.matrasport.dk/forum/index.php/topic,1517.0.html

Today's update, this time about new wiring loom in the engine room:
http://www.matrasport.dk/forum/index.php/topic,1570.0.html

First update this year:
http://www.matrasport.dk/forum/index.php/topic,1894.0.html