Dcoe, Dcom Choke Tubes?

[drmo 5]

Hy everyone!

 

Does anybody know if the Weber 40 DCOE and 40 DCOM choke tubes are the same? Christopher maybe?

[drmo 5]

Nobody??? I would just like to know if DCOE choke will fit the DCOM carb.

[Baz 421]

i should imagine so, as DCOM's are just the same, just OE fitted iirc.

 

Ashley Peddle may know as he has DCOM's a while back.

[christopher 5 1 Cars]

Hy everyone!

 

Does anybody know if the Weber 40 DCOE and 40 DCOM choke tubes are the same? Christopher maybe?

 

 

I an not sure about this. I have never had DCOE chokes. The 34mm ones that come with the Rallye should be more then enough for most TU applications.

 

I have some DCOM ones in the basement. Maybe you can take some pictures of DCOE ones if you have them

[Ryan 99]

All the jets and tubes should be interchangeable afaik, as the DCOM is just a slight update of the DCOE.

[drmo 5]

Ok, so they'll fit. Thanks guys for quick answers.

 

Here's a photo Christopher:

 

[trogboy 17]

No they're not!

 

I've not been on here in a while so I've only just seen this.

 

When I replaced the 34mm chokes in my DCOMs with 32s I had to use those made for a 45 DCOE as the 40 DCOE ones had too small an external diameter! You'll also have to drill a small depression into the chokes for the locating grub screw to sit in.

 

Getting 32mm chokes for a 45 DCOE isn't easy either.

 

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[christopher 5 1 Cars]

No they're not!

 

I've not been on here in a while so I've only just seen this.

 

When I replaced the 34mm chokes in my DCOMs with 32s I had to use those made for a 45 DCOE as the 40 DCOE ones had too small an external diameter! You'll also have to drill a small depression into the chokes for the locating grub screw to sit in.

 

Getting 32mm chokes for a 45 DCOE isn't easy either.

 

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I always suspected this. but never had it confirmed until now!!

[drmo 5]

You're right. The DCOE outside diameter is smaler than the DCOM, but just the thick part of the choke, the thin part is ok so they fit inside. At first I was woried that they wouldn't fit, but in the end I didn't have any problems.

 

 

 

The gap between the choke and the housing is not important becouse the aux. choke comes over the choke.

 

So you're saying that 45DCOE chokes, aux chokes are interchangeable with DCOM carbs?

[trogboy 17]

The chokes are (all bar the drilling of the dimple for the location of the grub screw). I couldn't comment on the auxiliary choke as I don't know the internal structure of a 45 DOCE.

[drmo 5]

The chokes are (all bar the drilling of the dimple for the location of the grub screw). I couldn't comment on the auxiliary choke as I don't know the internal structure of a 45 DOCE.

Thanks mate

[drmo 5]

This is how the aux choke of an 45 DCOE looks like. It is the same as 40 DCOM.

 

Edited June 19, 2008 by drmo

[Sam 4]

The newer dcoe's have grub screw location too.

[trogboy 17]

It looks very similar but then I would expect the 40 and 45 DCOE/DCOM versions to look very similar just be a different size

 

I'd imagine that the chokes I bought would have been pretty old hence why they didn't use grub screw location. Probably not much of a market for 32mm chokes for a 45 DCOE fitment.

[drmo 5]

It looks very similar but then I would expect the 40 and 45 DCOE/DCOM versions to look very similar just be a different size

 

I'd imagine that the chokes I bought would have been pretty old hence why they didn't use grub screw location. Probably not much of a market for 32mm chokes for a 45 DCOE fitment.

It looks like they are. A mate of mine has DCO's and the aux. choke is different than in DCOM's. It's longer, like in DCOE's. Both choke and aux. choke are not positioned in with grub screw, they just slide in.

 

I'm still discovering these carbs so not much of an expert (jet ).

Edited June 19, 2008 by drmo

[Sam 4]

The older dcoes used the trumpets to hold in the auxiliary venturi whereas the newer versions (I can't remember part numbers but 151 rings a bell) use a grub screw also.

 

32mm is also the proper crossover point from 40s. 34mm in a 40 doesnt give much flow gain over a 32mm.

[drmo 5]

The older dcoes used the trumpets to hold in the auxiliary venturi whereas the newer versions (I can't remember part numbers but 151 rings a bell) use a grub screw also.

 

32mm is also the proper crossover point from 40s. 34mm in a 40 doesnt give much flow gain over a 32mm.

You're probably right. In my opinion it just changes the peak power.

 

Here is why I was asking all these questions about choke sizes.

I built 1580 (TU5JP) engine with AX sport head, a 296° (11,25mm lift) cam and supersprint ex manifold. Head is alittle skimmed so the compresion ration has to be around 10,5:1. In my project I used DCOMs from AX Sport, where the choke is 34. I read somewhere that DCOM need biger chokes than DCOE, but don't know why. I thought that even bigger chokes (36 ) will solve my revinng problems past 7k rpm mark, but it didn't, it was just worse. I also tried bigger main jets and it did't help.

Then it acured to me that maybe there is something wrong with the ignition timing, becouse I still have a distributor from 1360 XR engine. I did some research and find out that haynes and autodata distributor specs are somehow different It confuses me that in autodata, XR (K1A) distributor gives less timing advance at 5k rpm (and everywhere else too) than AX sport M4A distributor, whereas in Haynes Data book it says the oposite. The TU3S (K2A) gives more ignition advance throughout the whole rpm range than K1A, but in Haynes it states that it gives even more than M4A....hmm...

 

I found out that the timing is somehow linked with compresion ratio. There has been said that with bigger CR u also want less ignition advance, to keep it from rattling...

...I kow that this is not the topic that I started so another question. The other thing that I was thinking off is that maybe the emulsion tubes are wrong or the main jet is still too small. The factory ones are F47 (yes strange number, probably becouse it was bult for one engine) and main jets are 138. I tried 140 main jets but it didn't help, so maybe 145 will help. I can still put bigger drill throu.

 

Today I will get a TU3S distributor and we will see if it changes anything.

 

Some help will be much apreciated. :wacko:

[Sam 4]

I had the same issues as you, I ditched the brand new webers after many rolling road tunes and went to throttle bodies. I could never get the right power etc. The Tb's ran better, used less fuel and IMO sounded better. It is a different sound but that's nothing compared to how much better it drove. I ended up with somewhere between 150 & 160bhp. I made 150.5bhp on 40s but I think it was probably closer to 140 in reality as it seemed heaps quicker on the jenvey's. Mine was a 1600 with a 100k bottom end, QEP heavily ported and worked head, 280/277 catcam, Magnex manifold and exhaust (1 box), and a quaife box. I miss it!

[drmo 5]

M4A or M2A distributors are imposible to find It goes really good but some work has to be done to the head and anything else. With 106 1.3 rallye box it is slightly faster than 182 clio RS on a hill climb.

 

I think that it has a lot to do with the timing. The distributors are far from precise compared to ECU.

 

This is how it goes with a longer gearbox:

 

http://uk.youtube.com/watch?v=JYlJsO4yRp4

Edited June 20, 2008 by drmo

[drmo 5]

Have changed the K1A distributor for a K2A (TU3S)...drives a lot smoother and revs more freely. No problem till the 7.5k mark. Didn't try to rev it further becouse of the standard pistons and rods.

 

I think it cured my problem

[christopher 5 1 Cars]

AX Sport, where the choke is 34

 

AX Sports came with 32mm chokes and no trumpets. I have some in the basement

 

Have changed the K1A distributor for a K2A (TU3S)...drives a lot smoother and revs more freely. No problem till the 7.5k mark. Didn't try to rev it further becouse of the standard pistons and rods.

 

I think it cured my problem

 

Why not try a Tu24 one?

Edited June 23, 2008 by christopher

[drmo 5]

Don't know about that. Mine had 34s in them. Carbs and head came off the original ax sport motor.

 

Tu24 distributor is impossible to find...new one is not available any more from the dealer and if it was the price would be around 600€

 

The distributor from the K4M was lost somewhere....

Edited June 26, 2008 by drmo

[205Rallee 59]

Don't know about that. Mine had 34s in them. Carbs and head came off the original ax sport motor.

 

Tu24 distributor is impossible to find...new one is not available any more from the dealer and if it was the price would be around 600€

 

The distributor from the K4M was lost somewhere....

 

 

I've got a brand new TU24 one (well it has done 200kms) sitting in the garage. Changed to mapped ignition and now the only problem I have is the leads jumping off the coil pack!