009 question....

[Tofufi]

Tofufi, if you're following this i see on the VZI thread you went down this route, are you happy with the outcome? Also with ICT's do you know if i am likely to find the same markings within the carb than that shown with the Kadrons; are all these carbs similar in the way they are made up, just different names and probably quality?

I am happy with the performance - the engine was smoother to accelerate with the vac distributor. Sadly, a month after getting the kadron tapped for the vac advance, I took it off the road for a restoration (on-going).

I've now got hold of another pair of kadrons, which I am thinking of fitting to my bus. The first thing I did when I got them home was to PM 'Fredster' on VZi to ask him if he would drill it for me. He did my first one

The carbs work on the same principles, but I can't swear that the ICTs will need the drilling to be done in the same place. I'd imagine someone out there has a guide to it if they don't come with vac connections as standard? The kadrons are renowned for being a bit thirsty, but I got reasonable MPG from mine in the bug.

 

[Guest]

the thread on vzi is great for dells, but i would drill and tap the manifold and take the vacuum off from there, not above the butterfly valve, for webber IDFs or carbs with twin barrels anyway, dells obviously only have one barrel. I summise the vacuum would be a lot stronger and at least you dont have to mess about drilling an expensive carb body.

I bought the Webber Carb Book, which i would highly recommend if you want to find out information about the evolution and the working of VW carbs. Its actually a good read, even for a layman like me.

I've been trying to find out the best method of running a vac advance on a twin set up and most if not all have the vac take off from one single manifold below the carb. It does stipulate that you do need to keep the carbs well balanced which you need to do anyway.

thoughts please?

 

[matt-me]

Thanks everyone. If taking the vac from the manifold, to clarify this is the individual manifold for the left hand carb. Bear with me but i assume it is the stroke of the pistons which cause the vacuum, the faster the pistons stroke the more the vacuum, the hence the more advance at the dizzy? Whereas with the 009 there are weights which get centrifugually thrown out more the faster the engine turns, which cause the points plate to move and timing to advance? Is that about right??

And to balance the carbs, as i understand it, air filters off, listen to air being sucked in with kit or piece of hose, should be equal noise, if not what do i adjust to get equal noise, the idle screw?

Also one more for the pot; if i was starting from scratch looking at the base engine set up is there an order of things to check; Valve clearances, carb set up, points, spark plugs, ie is one item dependant on having checked/set another first?

Sorry for all the questions. I'll stop on this one soon and start on another. Keen to get to know the right things to do and not get drawn down a path doing the wrong things and wasting my time/cocking things up.

 

[Guest]

i would get myself a cheap carb balancing flow meter tool rather than listen, you need a trained ear to know the difference. You can get a cheap balancer in Halfrauds, i think its a gunson one £16ish, would do the job. The better ones are around £35

What you've said about the dizzy is right, but later VW SVDA dizzys, have both mechanisms, the vac helps the engine run better at idle and on acceleration giving the right advance at lower revs so no flat spots while the mechanical advance really comes into play at higher revs. I think the concensus is this is the best dizzy to go for, and if you can fit electronic ign to it even better still.

 

[Benyon]

Sorry for joining this thread at the last minute, but the 009 v SVDA is something I have dipped in and out of over the last few months.

With the electronic module in a dizzy, is the argument/discussion above still relevant, ie. an electronic module in a SVDA will be better than an electronic module in a 009?

 

[Clarkson46]

The only advantage to electronic ignition is it does away with the need to adjust the points.

 

[ronmidg]

matt-me said

If taking the vac from the manifold, to clarify this is the individual manifold for the left hand carb.

jonny said

and most if not all have the vac take off from one single manifold below the carb

tofufi said

The vac also helps make the advance change more quickly when you gently apply the throttle - no flat spot

clarkson46 said

The drilling has to be above the butterfly so that the vac signal is only applied when the throttle is opened

so thats 2 each for manifold or venturi vacuum.

I thought the manifold tappings on the twin ICT kit are for the balance tube which smooths low speed running?

manifold vac advance is full on at idle so reduces as the throttle is opened. idle timing is with full vac advance on.
venturi vac advance comes in as the butterfly lifts above the vac tapping hole in the venturi, any advance is then in addition to the idle advance.
now which is best for any given combination of engine/dizzy/carbs/tune is beyond me, but I dont see how they can both be right when talking about one specific combination.

My ICT kit came with no provision for a vacuum take off for ignition timing. My distributor gives me about 20 degrees mechanical advance, on top of static timing of about 10/12 degrees. (and by static I mean setting it to smoothest running at idle) so I get about 30 advance at higher rpm.

if I were to set my idle to smoothest running with manifold vac advance in operation surely It will give me less than 30 advance at higher speeds? ie not enough.

so for our dizzy (mine anyway) dont we need venturi vac advance?

 

[Guest]

ron, i think it depends on the carb type, for kadrons it seems to be above the butterfly, i dont think this is possible with webber IDFs etc?

 

[ronmidg]

johnny, agreed, the webers come with progression circuits which operate on light throttle and I wonder if this is their fix for the hesitancy, I think the conclusion I'm moving towards is that if using a distributer designed for a venturi vacuum tapping carb (as our vans have from the factory) then we will get the wrong total advance at speed if plumbing (and timing) for a manifold vacuum signal, I guess it should be feasable to modify the dizzy internals to enable more mechanical advance before hitting the stop to compensate but have never done this and dont know what would be involved.

I followed the aircooled link, >> tech articles>>choosing the right distributer, which is a really good discussion of the issues, then from main page>>catalog>>SVDA dizzy>>view product details>>required selection, the window to the right changes to describe the the way to provide the vac signal for whatever carb settup is being used. I think he uses 30 degrees mechanical from the Bosch on top of the static, or idle setting, and sets the weights springs combo to match the engine+carb characteristics. So this will dial in another 8 to 10 total advance compared to what I get from the dizzy my bus came with (a californian double vac canister) (on the split, havent done the tests on the bay), and give a tailor made advance curve. But need to read it over a few more times before I'll be sure I've really understood, and if right will be ordering one of these (more likely two)

 

[Guest]

then we will get the wrong total advance at speed if plumbing (and timing) for a manifold vacuum signal

What casues the wrong advance? is it the strength of the vacuum? is there a differential between the strength of signal of a vac tube taken above the venturi and one taken from the manifold? im not sure....

from what i read of one guy trying to get a signal from his kadron above the venturi, it was so weak as to be almost non existent?

we could do with a definitive 'sticky' as to the best dizzy/carb combo and where to take the vac signal from if using a SVDA with twin carbs

 

[Guest]

got pointed to this...

the green circle is for the vac take off

 

[MMMC]

nice one...so will that be on my ICT34's do you think? Has the one in the picture been drilled or is it already part of the carb?

 

[Guest]

ill check when i get home tonight , i hadn't thought of that. i would guess its been drilled.

 

[ronmidg]

johnny wrote

What casues the wrong advance?

Please remember I'm not speaking from knowledge here, but trying to understand what I should do with my untapped carb+manifold to match it to my stock dizzy which is designed to mate with a carb delivering a venturi vacuum signal, quite happy to be told I'm completely wrong.

I reckon my dizzy gives about 20 degrees mechanical advance, I set up my idle with the engine running and it turns out to be about 10 degrees static, I have no vacuum advance fitted.
If we add vacuum advance into the mix then if it is a venturi tapping it will not be present when I time the engine at idle, if it is a manifold tapping it will be present when timing the engine at idle.
So assume max vacuum advance is 10 degrees(I have no idea what it is/should be) and then run the engine with the throttle open so the venturi and the manifold are both showing not much depression.
With a venturi tapping the engine will run with the 10 static plus the 20 degrees mechanical advance.
With the manifold tapping the 10 idle advance comes from the vacuum, and the static advance is zero, so at high speed the engine only sees the 20 degrees mechanical from the dizzy.

So, I think I have to have a venturi vacuum signal if I want to continue to use this Dizzy.

 

[Guest]

same here, i assumed that it was simply butterfly open = vacuum, butterflky closed = no vacuum whether its above the venturi or on the manifold. Does the idle air circuit play some part in the vacuum?

 

[Guest]

my webbers are genuine italian and they seem to be off an Alpha as they have the duel fuel inlets, or at least they havent been used on an aircooled because they would have one inlet blocked.

This set definitely had a vacuum takeoff fitted from factory pipe is on place in one carb and the other has never been drilled/tapped, as in the posted pic.

 

[matt-me]

Do you have a balance pipe/outlet as well?. Have had a brief look at my twin ICT's and they each have a pipe which i have been told is th balance pipe and should be connected to each other. I have just bought some hose to do this. Can anyone advise how important this pipe is and what it's function is?

Speaking to someone else yesterday he said the ICT's have a vac take off as well. Will check tonight but it is not easy to see behind the carbs closely, will have to use a mirror i suppose.

 

[Guest]

i've no balance pipe, just a vac take off from one carb, i guess ill just have to keep on top of balancing

My carbs have been sent over to the US for a full clean and refurb yesterday 8) , they will have any necessary drilling, including balancing and enlarged air jets done before the clean and refurb. It wil lbe interesting to see whats done.

heres a link....

http://www.carburetorclinic.com/36_idf.htm" onclick="window.open(this.href);return false;

 

[matt-me]

I thought i would provide feedback on this thread to help others who may have followed it, or may have similar questions in the future.

Using my existing 009 - Followed all the tuning/set up tips and procedures (had changed plugs, leads, points etc). Best set up was advanced to about 10/11 degrees at idle. Have been told should be 32 degrees advance at 3000 rpm but didn't have kit to read the revs. Actually my bus ran the best it ever had but still a little sluggish to pick up quickly/from low revs. Was pleased with the result.

Found out my weber ICT's come with a vacuum outlet as standard (had lost manual), so didn't have to go down route of tapping into casing and inserting new.

SO, bought a second hand SVDA from kindly Robin at C&C to test run. Robin gave me loads of help but he actually favoured the 009 in his experience (opinions is where we started). Bought some vac hose.

Fitted SVDA and set it up best to 10 degrees advance (remember don't know what my settings should be as standard as it is a re-con engine). Checked everything else again!!

Road tested and it pulled away like, dare i say, a car, straightaway. Didn't have to welly it to get it moving or to get through the sluggish point, which is a joy when changing gear, up and down. It has really transformed the way she drives, my wife agrees totally, regretably!

Conclusion, SVDA's for girls and 009's for boys - joke.

No really, i can see there is perhaps a bit more grunt using the 009 but only after you have wound it up to get through the sluggish point (some would say flat spot) so by that time you have lost any advantage anyway.

I'm sticking with the SVDA, combined with twin carbs, pulling accelerating well (well...), i am very happy. MPG great improvement too.

One final thing i found during all of this, the real mechanics, who are also owners, i have spoken to about all of this prefer the 009 and it is odd i find that all new or re-con engines advertised come with 009 as part of the package. It appears it is more the everyday user, who also has some idea of how an engine works, and who has actually compared the two, come out in favour of the SVDA

Hope this helps.....................

 

[matt-me]

I should add Clarkson46 and Tofufi were right along, respect and thanks to you both