I'm lucky enough to have a spare DMTR for my car (mk2 1.3 Square) which is not much use to anyone else without the adaptor plate.

So I thought I'd buy the following DMTL servicing kit which I believe will fit the DMTR am I right?..

http://www.fastroadcars.co.uk/shop/index.p...mp;productId=91

I can take my time and strip it down and maybe even learn more and then maybe service the one on the car?

Also if I was going to buy some jets to maybe lean the carb (a known trait of these carbs)which ones would I buy? I might well be getting the car rolling roaded so might be worth having some spares although the garage might well have plenty in stock as they specialise in older car tuning.

Your views? My car has GK inlet and straight through G40 back box exhaust.

Standard jets are..

Primary

idle 45

main 100

emulsion f22

air 155

Secondary

idle 70

main 115

emulsion f30

air 185

Someone suggested (Hypojam remember him)

Primary

idle?

main 105

emulsionf30

air 155

Secondary

idle?

main 115

emulsion f30

air(roughly)175

what about idle? seem to remember someone saying going bigger prevents blockages?

Finally I'm wanting a balance of efficiency with performance basically reliablity is the aim :-)

Cheers MacColl

Edited 3 April, 201016 yr by MacColl

seems madness to fit a big idle jet to sop blockages

mines been fine for over 2 years on the std jet ...and if it blocked i would look into why , such as a dirty air/fuel filter etc

have you emailed fastroad cars ? he seems fairly helpfull

Alright mate, thought you might appear :)

Yes my idle jet is generally fine, will go months with no probs then I'll have a week of dirt getting in there like bits of salt! and rust coming off the exhaust manifold finding their way into the whole air box. Also ran fuel tank very low at one point which I reckon has allowed build up of crap. I'm just not getting good idle, generally keep it turned higher to prevent any chance of cutting out. It seems to fluctuate when hot.

The winter has been harsh and I reckon a good service kit on these carbs would probably help. I did E-mail fast road and got a friendly reply saying that some of the DMTR's have a different gasket pattern but all other parts are good for service anyway.

So I'll probably go for it, maybe see if anyone has advice on what jets would be worth trying as back up?

Just wanting to address various issues with the car like this and some rust, some minor arch work, maybe light upgrade,5 speed box and basically make it reliable too see me to the end of Uni (Sep 2011).

have you blocked off the breather as it goes in the carb side of the aircleaner ...mine used to get bits of poop from that when i ran the pierburg, i vent it to air now with the weber

i get the rust up the hot airpipe too...mad how it sucks it up tbh , but the airfilter catches it

cant see a bigger jet curing any blockage problems anyhow as it can only be a fraction bigger

Yes that breather hole in the air filter housing is blocked up with a bit of wooden dowel. The crank case breather now just has a large single pipe venting to air pointing back in the bay.

Yes I had lifted out the air filter and basically the bits of rust were everywhere. I ended up having to remove the whole air filter housing in a public car park.

If I could get more of an idea of jet options I would probably make an order tomorrow although I can steal the emulsion tube from the spare carb to get two f30's (these cost about £17) jets are £2

Where are the other fellow Weber twin chokers? lol.

No one else roll with DMTR or DMTL?

Would be good to get some Input on what jets might help improve things?

I found this thread in Club GTI which will be great for strip down..

http://www.clubgti.com/forum/showthread.php?t=179242

just you n me lol

have you considered a rolling road session? get the jets right rather than guessing

Have you got the standard 22mm venturi version of the carb?

The general rule with these carbs is best main jet size = venturi size x 5. The reason the jets are very 'lean' on the first stage as standard is the f22 emusion tube richens the mixture at part throttle. Having the F22 means the pump jet doesn't need to be very large (IIRC it's a 40 on the DMTR) so if you switch to a leaner emulsion tube and richer mains you might find initial throttle response a bit flat. I experimented with various main jets and emulsion tubes but because I didn't change the pump jet I ended up going back to the original settings because I found they were the best for driveability. If I'd gotten a bigger pump jet it might be a different story. Dvderlm has spent alot more time experimenting with various combinations I'm sure he'll have some advice once he sees this thread. :)

^^Well I'm kind of leading up to that, found a place in Edinburgh which I'm hoping to get to, it's walking distance from my sisters so I can just drop it off. Think the guy said it would cost about £60 to get it on the rollers and he seemed very helpful. Don't know how much it would cost in total depending on jets and time involved. I suppose it would only take an hour tops?

This is the place..

http://www.cartuningclinic.com/index.php?o...c64c7e02d977c8c

I'll do the carb service and get some other bits done to ensure the car is running properly from my end and I'll hopefully get them to tune it.

Gaz your a legend, just got that answer in before this reply, I'll see what dvderlms got to say and then maybe buy a few jets with that service kit. Think the rolling road is going to be the way forward.

Thanks to Steve also.

Edited 15 February, 201016 yr by MacColl

id confirm if the guy has jets and bits on the shelf if he needs them

some places just to a power run and tweak the mixture/timing , kinda suggests this on his site

i recon it would be money well spent if they can rejet it to near mint

Edited 16 February, 201016 yr by steveo3002

£60 sounds very reasonable!

This thread has been calling me...

I once idly speculated that bigger chokes and hence idle would help avoid blockages, but redroller and a others shot the idea down in flames. Sadly I can't find the post.

I don't think it is this?

Anyway, twin F30's is taken from a Fiat 128p rallye. F30's are good all rounders but often need 5% larger mains.

However I do use a larger idle with F30s. For me the 50 idle stops a bog (lean hole) when I accelerate moderately hard

especially pronounced when I experimented with huge 127/F30/185 (but the fuel consumption suffered with that big main).

The car spends longer on the primary progression jets (up to 2800rpm ?) and the idle circuit (slow running circuit in all other languages)than with a 45 - so I still use a 50 idle with my extra lean 105/F30/220+ primary.

I also use a larger 50 pump jet. It's the same amount of fuel that gets squirted (twice), but it arrives faster.

Petrol is denser than air so this compensates for the inrushing air leaning out the mixture when I accelerate really hard.

Weber warn that on some carbs the pump becomes a power jet at what and can worsen economy considerably.

So far I've not noticed that as a problem on the DMTR unless I revert back to 45(or 50) and 100/F22/185 primary.

I'll admit that the F22 feels nippier from 1000 to 2500rpm than the F30 so don't underestimate it,

but I find I get some faltering at gentle throttle settings - when the F22 should not be involved.

Read 'Three circuits' here - it's about DCOE so 1.5 to 2 turns out for the idle not 0.75 - but same principle applies.

http://www.teglerizer.com/dcoe/inglese/inglesetuning.htm

Every engine is different. I've got high-compression, large cam overlap and Dignition

to retard the spark based on revs and manifold pressure, and I drive in East Anglia - effectively sea-level.

Your engine and how you drive will most lilely be different. A rolling road tune by an expert will help

remove any doubts.

I'm prepared to travel smoothly if a little slower and use less fuel most of the time, but have large reserve power

when I need it. That's what a progressive carb's second barrel is for. I'm not driving on the autobahn so I don't need the

top end provided by a 26mm secondary like my original Pierburg had but the 22mm DMTR helps flow velocity. My next worry is hitting inlet valve mach 0.6 airflow which is not good.

Extra reserve can be achieved by two methods.

• Firstly, use thin emulsion tubes so the well has more fuel to draw on. F22, F24 and F33 are all good candidates.
• Secondly, lowering the float. The mixture is deliberately weakened so much larger idle and main jets

  can be used for a richer top end. This last trick lets X1/9 racers use 150/F30/240 secondary with a

  34DMTL and 27mm venturi from a Lancia on a 1300cc engine.

Great stuff thanks :) I'll consider getting these jets before ordering service kit but might establish if this car tuning clinic would have jets at hand anyway for proper tuning. I'll certainly give them your views along with other bits I've hoarded.

I really should be writing an essay for Uni right now so I'll need to wait till Friday and then I'll try and get my head more into this.

Just another two questions (this thread is definitely a sticky candidate)..

Does anyone have an exploded view of the DMTR? not the DMTL which I already have.

Also what is the best vac tube placement, on the front? (1 on pic) or on the side? (2 on pic) Mine is on the side with the front blocked off. This is a picture of my carb when I first got it..

Cheers again MacColl

Does anyone have an exploded view of the DMTR? not the DMTL which I already have.

I once took an angle grinder to a Pierburg 2E2 but I didn't catch it on video.

Oh, not that kind of explosion.

No sorry, my DMTL diagram's from a Landrover courtesy FSE and I think Fastroadcars sent a DMTL one from a Fita Ritmo along withthe DMTL service kit.

Google is your friend

dmtr pic

Also what is the best vac tube placement, on the front? (1 on pic) or on the side? (2 on pic) Mine is on the side with the front blocked off.

I don't think it matters so long as the pipe fits tight.

My side one goes to the temperature valve in the air cleaner that opens the hot/cold air flap in the intake.

My front one (actually rear as my carb is mounted backwards for quicker reversing) goes to the MAP sensor in the Dignition.

The ancient fitting instructions I have for kit 18870975 say 1 (front H) goes to the air filter, 2 (side E) goes to the distributor vacuum advance.

Edited 17 February, 201016 yr by dvderlm

power jet at what

Eh?

I wrote "W O T" for Wide Open Throttle.

Think a spelling checker must be removing textspeak...

Kerpow!

I'm betting that the filter on mine (part 3) will be well clogged.

I also found this air filter that I might go for in the summer?

http://cgi.ebay.co.uk/WEBER-DMTR-DMTL-SPRI...7#ht_1007wt_939

Yes I didn't even think of the front vac hose tube being for the temp valve on the air intake. Mines constantly closed with the hot air coming straight from the front inlet.

Hiting the Image search with Weber DMTR is weber and Club Polo tastic..

http://images.google.co.uk/images?gbv=2&am...t=0&ndsp=18

Cheers once again

Edited 17 February, 201016 yr by MacColl

^^ There are certain words you can't use like F O R T William which comes up- thought William????

I thought I was loosing it too lol.

Kerpow indeed.

I also found this air filter that I might go for in the summer?

I think nick0323 had one and maybe DannyLee too before he went twincarbed.

Didn't hear anything bad about them. On a hot summer day I'd want cool dense air from outside the engine compartment myself.

So I'm just waiting for the guys at Fast road to confirm that the DMTL service kit is suitable for my spare DMTR. There going to check with Weber which is good of them.

The great thing about being single is you can stink out your kitchen with paraffin to clean a carb without any grief lol..

It's cleaned up real nice. The accelerator pump diaphragm was really dry and perished which will definitely benefit a replacement and there's more bits to come out and clean up like the pump injector..

Edited 27 March, 201016 yr by MacColl

Just removed the pump injector and hope I haven't damaged it,was a nightmare to get out. There will be a new O-ring to go on it.

I take it is meant to have a very small needle hole which I can blow through, just hope I haven't crushed it!

Yes I didn't even think of the front vac hose tube being for the temp valve on the air intake. Mines constantly closed with the hot air coming straight from the front inlet.

Cheers once again

dude !!!

What do you mean dude? lol.

I just block off that vac tube in the carb and have the hot air pipe going straight in the front intake of the air filter. The temp valve is not engaged at all, as in closed to allow full air flow in from the exhaust manifold area for winter. Did I not make any sense lol. not unusual for me.

As for the service kit, It's different from the DMTL apparently which means £30 for a kit that they have sourced from Weber.

just suprised you didnt realise the set up....hook it up it should work well :)

Yes your probably right, never associated that vac function with the weber and I don't have a proper hot air shroud above the exhaust manifold, just the metal tube. There was a guide for carb freezing where you do what I have.

There's a whole bunch of stuff I want to get done to this dam car in order to get it rolling roaded, so dam annoying with Uni taking over. Once I'm trained and working think I'll go for the Chequebook approach lol.

"chequebook approach"

Never thought I'd hear someone from Scotland say that

I'd be interested to know what's different for the DMTR service kit.

I'm sure I used a DMTL gasket and the pump diaphragm's the same.

Needle valve was 1.75 not 1.50 I recall, but since I can go 200 or so yards on the well contents at full throttle with a 1.50 I don't think I'm in any danger of insufficient flow that I need 1.75.