If all your ignition components are in good condition, then the jerkyness will be a lean mixture or an air leak. I'm currently working on a custom airbox design for a double choke weber dcd, have you got any further with making yours? I'm needing equations for volume and inlet diameter etc.

I'm getting conflicting symptoms here really. On the front of the pierburg, there are two little tubes. One is for the vac advance and the other is a temp sender or something. I had the vac advance connected up and the temp one block off. When idling (if you can call it that) it wasnt very happy, but when i took the blocked off tube off, it picked up a lot, suggesting that it needs air/ too rich. I've left it off for now so it will run better but i obviously want to get it right. I fitted the pressure regulator and that seemed to reduce the problem but it hasnt solved it completely, its still quite jerky low down.

When designing the plenum i asked around and no one could really give me a concrete formula for volume. I was advised that 150% of the engines volume would do so i went with that. I read quite a lot on the internet about it and the main thing to consider is making sure all the air inside gets used up. Just make sure the inlet diameter will allow the airbox to be filled without restriction. If you get the capacity right, all the air will be used up and a good amount of vacuum wil be generated resulting in good throttle response and performance. Just read read and read some more, its a bit of a black art.

The fabrication stuff has been put on hold as i didnt think it would take this long to get the bloody thing running right, really starting to piss me off. I just want it to run and drive like a normal car. The quest continues anyway!

To keep plastic arch trims or to lose plastic arch trims?

That is the question...

Anyone know how to check/ adjust float level on a pierburg?

The car is running super rich but I've got the mixture screw wound right in. Not tooo sure where to go from here really.

Bit of an update/ plea for help.

Took the carb apart again this morning and found that the stage 2 progression lift pipe was blocked. So unblocked that, made sure everything else was in order and now it idles sooooo fast! Before, it would barely idle, was up and down up and down and now its pretty flat and constant but idles at around 2000 rpm!

I've tried adjusting the idle speed screw but you have to unwind it around 5 whole turns to get it anywhere near correct. These should idle around 950rpm shouldnt they?

Why is nothing easy with polo's? And if someone says thats what makes them fun or something along those lines i will maul you...

weber.

weber.

Was waiting for that.

If you can find me one going for under a bazillion pounds id gladly snap it up...

I think I have a 32/34 DMTL somewhere.........

DMTR or DMTL , there should be loads on ebay!

Edited 26 October, 201114 yr by MaxMax

Right ok while we are on the subject of webers, i actually bought one aaaages ago for this project, but when i received it, it looked different to the ones I've seen on here so i presumed it was wrong so never used it. I didnt have a adapter to fit it to the manifold so i made one but the two holes were completely different, reinforcing my fear that this is the wrong carb. Ill put a load of pics up and see what peoples reactions are. The only way i can get the adapter onto the mani is to either weld it or bolt it on. I didnt really want to do this with my GK but i have a standard manifold i dont mind doing it to.

Check it..

Removed the images as they were huuuuge. Problem solved anyway...

As you can see, the hole in the manifold is smaller that the adapter and I've made the adapter to exactly follow the contours of the two holes in the bottom of the carb.

Another problem seems to be the throttle cable, it pulls in the oposite direction although i guess i could resolve this by replacing the standard cable (too sort to wrap around) with a bicycle cable.

And also, not sure what air filter will fit this...

The carb has 32/34 DMTL stamped into it

Thoughts?

Edited 10 November, 201114 yr by azza46

It looks to me like a land rover component to me, similar to what I used a while ago.

What size are the venturis? And jets? I'll be able to tell you for definite.

It looks to me like a land rover component to me, similar to what I used a while ago.

What size are the venturis? And jets? I'll be able to tell you for definite.

Looking at the second picture (view from top) the lower jet is 115 and the upper is 110.

Venturi size 32/34. Presuming thats what you mean by venturi size?

Right, bad news all round in terms of the car today. Took it round my mates to have a look. Big air leak coming from one of th blanked off bits on the inlet manifold, sorted that. The carb was still letting in way too much fuel though. Firstly, the rubber mounting flange has a big tear in the side of it, not sure how, but it has. This is made worse as i ordered a brand new one as the one that came with the carb was buggered. S orderd a new one and then found one in my garage, looked brand new, nice n stiff etc. But now its shagged, and i had a new one but sent it back...joy.

Next, the second stage vacuum unit doesnt work, so it has only been running on one choke. Doesnt effect idle but effects power, massively.

Next up, the diaphragm in the 'part throttle enrichment valve' is torn. This is where i suspect fuel is getting in as its not sealing off.

So...phoned up the guys at the carb hospital and grand sum of the parts = £110 + vat. Pretty annoying considering i paid around 20 quid for the carb. that i was told was fine. Why cant people on here that sell stuff just be honest and stop wasting peoples time and hard earned money?

Not really too sure what to do now, I've done a major bodge job on it but dont knwo whether to order parts. It will be on bike carbs soon enough (looking forward to all the roblems that come with them).

I took the enrichment valve assembly apart and put a touch of super glue on the little tear in the diaphragm, just to seal it up for now. I had a gasket in the re build kit i bought so i stuck that on too.

In regards to the stage 2 vacuum unit, i have taken it off and replaced it with possibly the biggest bodge i have ever done, but i just really wanted to know how the car went when the second choke opened as I've been driving around on the little one only so far.

Taken the pic off as it was huge

Edited 9 November, 201114 yr by azza46

Don't pay for the parts! You can buy poo carbs cheap anyway! Not worth the money and if you got a weber chilling on the side may as well look into that or be patient and wait for bike carbs as it does run currently?

Car is running baaadly at the mo. Was going along the motorway, tried accelerating and then just started losing speed to no apparent reason.

Went to start it this morning and nothing, flat battery. Went after a jump.

May be a weber shaped light at the end of the tunnel though, i pray that this works. I just want a car to start, drive and stop when i want it to, is that too much to ask?

Also, does anyone know where i can get my hands on the rubber mount that goes between the inlet mani and the carb?

Thanks.

lets get a weber on this, and post up a vid when its on, they sound sweet when the second choke opens.

lets get a weber on this, and post up a vid when its on, they sound sweet when the second choke opens.

Will sound even better with all its newman cam goodness as well.

Reeeeaaaally need to get an aftermarket exhaust on this!

Just ordered a new inlet mani to carb flange so should all be working a bit better soon hopefully!

old skool fast beats sticking a computer into it to make it faster, like I said in my PM's it made my not very good mk2 polo a lot quicker so with a Weber and a newman it should be epic.

I realised late last night it probably would have been better for me to drive for an hour to hand deliver the carb to you. bloody Royal Mail.

New weber is on (big thanks to leonh) and its running muuuuuch better. Pics and maybe vid to follow.

Still got a few probs with the car though so anyone willing to have a stab at what they are, feel free.

1. It struggles to start sometimes. Not sure why, the battery, alternator and starter motor are ok. It seems to struggle to start while I've been driving it for a long time. Possibly drawing current from somewhere? Electric fuel pump possibly?

2. When sat in traffic, i can see smoke coming from the bonnet. Not huge amounts, but definitely smoke. Not sure whats burning. The oil is black if that gives any clue.

3. There is a rattly noise coming from the front end. Not sure if its always there or not but you can hear it more when coming off throttle.

Think thats about it.

New weber is on (big thanks to leonh) and its running muuuuuch better. Pics and maybe vid to follow.

Still got a few probs with the car though so anyone willing to have a stab at what they are, feel free.

1. It struggles to start sometimes. Not sure why, the battery, alternator and starter motor are ok. It seems to struggle to start while I've been driving it for a long time. Possibly drawing current from somewhere? Electric fuel pump possibly?

2. When sat in traffic, i can see smoke coming from the bonnet. Not huge amounts, but definitely smoke. Not sure whats burning. The oil is black if that gives any clue.

3. There is a rattly noise coming from the front end. Not sure if its always there or not but you can hear it more when coming off throttle.

Think thats about it.

When you say it stuggles to start, do you mean it stuggles to turn over? If so then its more than likely the starter motor or battery.

Regarding the smoke, leave the car running for a while on the spot (Keep an eye on the engine temps)

Have the bonnet open and see if the smoke is visable, it may be the exhaust manifold and/or the new gasket bedding in. Have a look for yourself and see.

The rattling i can't help with without seeing the car.

What jets are you using then? The 110 and 115 are the main jets, primary and secondary respectively.

The venturi's are not 32/34mm, that is the throttle size, IIRC the venturi's are 24mm & 25mm again primary and secondary respectively. To be honest its not the worst carb in the world, but its not the best option either. With it having very simular sized primary and secondary chokes/ventruis, it makes it a slightly lazy carb (suited to the landrover engine)

the vac hose set up you described was exactly how I ran it, have you got any pics of the throttle cable.

and MaxMax its not that bad a carb, sure its not a whacking great set of twin 40's but on a mk2 it's a damn good improvement over the 2E3 and the chokes are quite a bit larger, also due to the fact that carb has covered only a couple thousand miles in its life will also work in its favour.

when i say struggles to start yea i mean struggles to turn over, sounds like it got a flat battery. I've noticed though that when i come out in the mornings after not using it for a while its fine, go for a short drive, still fine, but when i got for a longer drive, it struggles. I think it must be drawing power from somewhere. Maybe I've got the fuel pump wired in wrong.

In terms of jets, I'm not sure, i can have a look but it seems to be running good at the mo, idles a tad high but if i fond the idle speed screw ill turn it down a touch. Anyone know where it is?

Also, i found the graphs from the flow bench tests i did on my cylinder head, quite interesting to look at and may help some others with cam choices!

First graphs are how the standard ports compare to the best they could be.

Inlet

Exhaust

Next are what i managed to get them to vs best

inlet

Exhaust

The next two are the before and after comparisons

Inlet

Exhaust

As i said, you can see when the ports stop flowing over a certain amount of lift. The measurements are in inches but you can convert it to mm to help decide what lift cam you need. No use getting a cam that lifts to 12mm if it stop flowing at 7mm...

Sorry for the quality, they are on paper so took pics of them on the phone lol.

Cheers.

Edited 10 November, 201114 yr by azza46

how is everything going with the carb mate? is all well?

how is everything going with the carb mate? is all well?

Hey buddy. Yea It's going very well on the new carb thanks. Just trying to sort out a few of the existing problems like the rattle and the electrical starting problem. All will be well soon hopefully.

Bit of an update!

Just been fine tuning all the problems out a bit really. Was struggling with top end speeds recently so I've turned up the pressure on my fuel pressure regulator (not sure if i featured this in the thread) and thats sorted the problem a treat.

Shes all timed up properly as well now so its running very well, who would have thought!

Smoking has stopped since I've put coolant in it so thats cool!

And had a look underneath and the lower brace is hitting the gearbox mount and is very close to the exhaust so i think this might be the source of the rattle.

Things I've still got to do are hook up the reverse light, pretty sure i know which connectors they are but due to the different location of the connectors on the new box, the wires need lengthening.

Small piece on the handbrake needs welding up to give me a handbrake again.

Apart from that its doing really well! Really happy with the power now its all set up right. Was a little dissapointed at first but its hard to get a good impression when the cars not set up right.

Next plans are check plug colour and adjust mixture accordingly.

Fit the four branch. Will need a cat back system first but haven't got the money yet :(

Bike carbs at some point in the future. Quite happy with the weber at the mo though

Seems to be a bit of a lag pulling away under part throttle so maybe a bit of adjustment to the accelerator pump or a jet change.

Wider wheels are needed pretty badly.

But at the moment I'm going to give it a good clean, change the plugs and enjoy it! Dont think me or my wallet can bear any other problems with this car. Its been a real struggle getting it set up and didnt think i would ever get there but feels really good to have finally got there! Came very close to selling it a while ago it was getting me down so much!

Anyway, sorry for the essay, ill give it a clean and get some pics and vids up!

Thanks.

Had her up on the lift today at colege to see if i could find this rattling noise. Pretty sure i found it. The bracket that connect the exhaust to the started motor wasnt attached so had swung down and wis rubbing on the driveshaft.

Also ground a bit of the gearbox mount away to relieve it from the strut brace but now i think because it has room to move, its knocking on it as now I'm getting a new knock under acceleration and deceleration. May just take the brace off, not too sure how much it improves the car really.

Car feels a lot better to drive now though. Was getting quite a lot of vibration at low revs and idle but now shes smooth as silk! Well...compared to what it was like lol.

Ill give it a clean tomorrow hopefully and take some pics.

Oh, and someone very nice decided they didnt like my passenger side wing mirror very much and decided to smash it off.....thanks a bunch! WA**ER!