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New 6 mm hose connection plus cold start mechanisms removed
by Anders Dinsen ... May 17, 2010, 09:54:11 pm
Fuel leaking out of the cold start (choke) mechanism on Weber DCOE carburettors is a well known problem, particularly when carbs are inclined like they are on the Murena S-manifold (no less than 15 degrees there). There's no cure, but the mechanism, which is open in the bottom, where it sucks in air, can be replaced with blanks, which will improve the situation.

But what about cold starting the engine?

I'm happy to report that with the DCOE's that's not a problem at all: Fuel runs so well down the barrels and into the engine, even when it's cold, so a single splash with the accel jets is all that's necessary to start the engine on even the coldest days.

Compare with the photo from August last year:


Last year I replaced the cotton braid hoses with quality nitrile fuel injection hose. I had a short piece of 6 mm hose running from the tank to the filter - this was not replaced then, but it started cracking in the surface. A word of warning: This particular hose piece is 6 mm fuel injection hose from Biltema. Not recommendable, I'm afraid!



 
« Last Edit: May 21, 2010, 12:07:11 pm by Anders Dinsen » 0 Comments | Write Comment

New engine wiring loom and a few small changes
by Anders Dinsen ... August 21, 2009, 10:15:39 pm
For quite a while, I have wanted to replace or repair the engine wiring loom. I had several reasons: The green connector next to the ignition coil was suffering from overheating and a bad connection, I have installed a three circuit immobilizer circuit on "top" of the old loom and it was a bit "bulky", and the tape was falling off a few places on the old loom. So some time ago, I started fabricating a completely new wiring loom with the immobilizer circuitry integrated.

Working on the engine wiring is more or less impossible unless the induction is removed, so the carburettors had to come off the engine. While they were off, I replaced the plastic spacers between the manifold and carburettors with a different kind of spacer: A "MISAB Spacer". These are better in several ways and are generally recommended over the plastic ones, but the reason I chose to replace them, was the the plastic spacers did not seal perfectly in two places on the manifold, where the O-rings potrouded slightly over the edge of the manifold. This was between the two middle inlets. The MISAB spacers have cured this problem.

I also wanted to replace the cotton braided fuel hose I originally bought for the carburettors with fuel injection style hose. This was recommended to me by a friend, who told me that the cotton braided rubber hoses has a tendency to disintegrate when subjected to unleaded fuel  Shocked I was not aware of this, but on the other hand had noticed (both on the Weber's and on the original single Solex carburettor) a few black grains in the float chambers. These could only have come from the fuel hose.

Since this could quickly evolve into reliability problems (e.g. fuel lines in the carburettors becoming blocked), I decided to replace the fuel hoses with modern hoses. They don't have the nice look and feel of the cotton braided hoses, but what help are good looking fuel hoses, if they detoriate slowly? Wink

Here's a link to a series of photos showing the transplant:
http://gallery.dinsen.net/v/biler/Matra/technical/electrics/wiringloom/

And the finished result for the impatient:


I had only one problem with the new loom: The alternator didn't charge!

This confused me a bit, as I was ... Read More
 
« Last Edit: August 21, 2009, 10:24:29 pm by Anders Dinsen » 2 Comments | Write Comment
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Re: New engine wiring loom and a few small changes
by Anders Dinsen ... March 05, 2013, 10:14:13 pm
Hello
Where did you get your airfilter/innlettbox ?


The filter is the original filter. The airbox is custom made out of sheet steel and painted black. Nothing special there Smiley

/Anders
 
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Re: New engine wiring loom and a few small changes
by pero ... February 24, 2013, 09:30:40 pm
Hello
Where did you get your airfilter/innlettbox ?
 

130-F9-190
by Anders Dinsen ... July 08, 2009, 08:44:37 pm
After a week in the mail, new jets arrived on Monday and main jets are now down from 140 to 130. Emulsion tube still F9. Air jet reduced to 190 to be on the safe side.

Difference in performance is obvious: Where it used to drop off over 5000 rpm, it now produces full torque all the way to 6000 and above! This is how the Holbay cam should perform.

I did a quick run down my local motor way yesterday, and I dare say the performance is absolutely satisfactory. With the engine still "taking off" at 3000+ rpm, but rev'ing freely up 3000 more, the car can really do some serious "pulling". Still accelerating hard 150 km/h in fourth, I don't dare guessing on the top speed!

No work is done until the paperwork is done, as they say. And that applies here too: I have to go back to the rollers now and finish the tuning. I've got a few more air jets to play with to get the very top end absolutely right, but so far my car has never felt better than this! Smiley

I've got no photos this time, so you'll have to do with your imagination Wink

However, here's a link to my jetting chart with the entire jetting history. I may write some notes about it at some point as my comments probably need some explanation. After all, the chart also reflects the "learning process" I have been going through (not to mention the problems I have had):
http://tmp.dinsen.net/murena/jetting.html

/Anders
 
« Last Edit: July 08, 2009, 08:46:46 pm by Anders Dinsen » 2 Comments | Write Comment
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Re: 130-F9-190
by Anders Dinsen ... July 17, 2009, 10:00:32 pm
Thank you very much, Roy. Unfortunately it still seems to run too rich as this photo of the spark plugs shows:



This photo is taken after town driving, which explains the carbon despite the middle and top being correct (or at least much leaner than they were on the rollers). The idle jet was 50F9, so I have changed it back to the 45F8.

But, as everyone can see, there's something wrong on the two midd... Read More
 
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Re: 130-F9-190
by roy4matra ... July 17, 2009, 02:00:19 pm
Difference in performance is obvious: Where it used to drop off over 5000 rpm, it now produces full torque all the way to 6000 and above! This is how the Holbay cam should perform.

I did a quick run down my local motor way yesterday, and I dare say the performance is absolutely satisfactory. With the engine still "taking off" at 3000+ rpm, but rev'ing freely up 3000 more, the car can rea... Read More
 

On the rollers
by Anders Dinsen ... June 25, 2009, 11:04:10 pm
The scheduled rolling road session in April didn't work out, and then I found out that the rear shocks were gone, so I had to postpone it until they came back from refurbishment, but yesterday the 24th of June, it finally happened: I had the car on the rolling road with F. T. Tuning in Svedala near Malmö: http://www.ft-tuning.se/



We spent about two hours mapping it, trying different jets, both in the idle (low speed) circuit, and the main circuit. It was too rich when we started, much better when we finished, but unfortunately we didn't have a small enough main jet to make it work perfectly, so this is only an intermediate result:



This cam should go far beyond 5000 rpm for max power, so the result of 130 hp on the top is not final at all. The max torque at 3300 is 198 Nm, and that is quite okay and 5% more than an S-cam is spec'ed at.

The jetting we have arrived at so far is

Mains: 140 (too large!)
Airs: 200
Emulsion tube: F9
Idle: 50F9

Ignition was advanced well beyond the 12 degree mark on the clutch housing.

Next step is to buy a set of new jets and do another session.

/Anders

 
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Re: On the rollers
by Anders Dinsen ... June 28, 2009, 08:43:29 pm
I think it's pretty much standard to set up the car on a rolling road if you're tuning the engine. Exception is for the few carburettor experts who prefer using ears and nose to do it, or if you're building a fuel injected system and fit a wide band lambda sensor in the exhaust.

On the rolling road you can run the engine at any revs under full load. In practice, he floored it at low revs and the let it slowly climb up to the max. The computers the measured the power out... Read More
 
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Re: On the rollers
by Jon Weywadt ... June 28, 2009, 12:48:14 pm
Hi Anders.

That is a pretty serious tuning effort, but it appeals to my perfectionist side. Are you sure you are not a bit of one yourself?  Wink

Tell me how you arrange this, do you just call them up for an appointment, or do you have to "know" someone? Also, is it expensive? It sounds like you test it, change settings test again, etc. until you get it right. that could take all day, or Huh Huh
 

More jetting, looking forward to rolling road session
by Anders Dinsen ... April 02, 2009, 08:26:45 am
I have a moment to make some jottings before leaving for Provence in the Grand Espace.

The pump has really been running well - glad to have that sorted!

So I've been playing with jets again, and decided to try the 45F8 in the idle. Other idle's I've tried are: 50F9 and 55F8, both of which I think are a little too rich. The results are promising, but the change obviously did cause some other challenges a bit higher up in the range, where a flatspot occurs in the transition to the main circuit. This could be compensated by going richer in the main jet, but it doesn't appear to produce full power higher up then, and it hasn't cured the flatspot completely.

My conclusion so far is that while a 45F8 may actually work well, it may take some other changes to get it perfect, and this time I'm thinking of the choke tubes. The chokes that came with the carbs are rather large for a 40DCOE: 36 mm. Murena S was shipped with 34's in the 40 mm Solex carbs, and this is probably a suitable solution for a road car.

Here's the link to my jetting chart:
http://tmp.dinsen.net/murena/jetting.html

On the other hand: I know it can be tuned to run reasonably well (though probably a bit on the rich side) with a 50F9 in the idle and the 36 mm chokes and the universal F16 emulsion tubes, and the 36 mm chokes will certainly favour the top end, so why not go all the way: Forget fuel consumption in city driving, and go for a low end driveable, but high performing top end?

April 27th is scheduled for a rolling road tuning session at a Swedish tuning company: http://www.ft-tuning.se/
I'm going to take advantage of the advantageous DKK/SEK exchange rate, and I'm really looking forward to the trip to Skåne, which will also mean a chance to meet Helge, the owner of the white 530 that participated in last summer meeting (which I couldn't make).

Cheers to all,
Anders Cool

Here's a photo of my new engine wiring loom:

 
« Last Edit: April 02, 2009, 08:29:02 am by Anders Dinsen » 0 Comments | Write Comment

Most Recent
New 6 mm hose connection plus cold start mechanisms removed
New engine wiring loom and a few small changes
130-F9-190
On the rollers
More jetting, looking forward to rolling road session
New pump
Fuel starvation
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