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UK Luke 72 Sun Mar 11, 2012 9:45 am

Hello :)

Im hoping to pick your brains a little on WBO2 tuning carburettors, I'm somewhat limeted on jets (as in, to change them I will have to get them shipped in from the US) so I'd like to be able to tune them just on the mixture screws... its not too far out i dont think so should be ok...
at idle I'm at around 13-13.5 OK?
WOT 11.5 Rich ?
Tt doesn't seem to lean out much past 14 on the overun though... I guess i need to turn the screws in 1/8th each side and go again.

Any comments/help?

Luke

UK Luke 72 Sun Mar 11, 2012 1:05 pm

Ok so when cruising at 50mph ~2800 rpm I'm at 13:1 :o looks like smaller mains are needed... But then my wot would lean out wouldn't it?!

[email protected] Sun Mar 11, 2012 1:47 pm

http://www.thesamba.com/vw/forum/viewtopic.php?t=293837

borninabus Sun Mar 11, 2012 1:50 pm

you cannot accomplish what you are trying to do with the mixture screws.

kads use the same jets as PICT series carbs and the mains are also the same as mikuni motorcycle carbs.
you should be able to source something in country.

andk5591 Sun Mar 11, 2012 3:55 pm

As much as a pain this is, its a good ideal to get yourself a set of jets and put together a "kit". For me, I have 3 cars with Kads, so its easier to justify it. You want 55 and 60 jets and I would suggest 127, 130, 132 and 135 mains. And then play. Keep in mind that your idles will impact the ratio in the upper range, but not a lot. So, get the idle together first and then move to the mains. Something else is to make sure that your aceel pump nozzles are not siphoning fuel in the upper RPMs. This effect will make you crazy trying to use your wide band.

See this http://www.thesamba.com/vw/forum/viewtopic.php?t=398526&highlight=kad+accelerator+pump

mharney Sun Mar 11, 2012 5:57 pm

Check to make sure your accelerator pump squirters are not right in the venturi zone.. that will cause them to siphon and run really rich on high RPM WOT.

With stock venturis, 55 idle, 135 main oughta be close.

808OvalGreasemonkey Sun Mar 11, 2012 9:13 pm

Your idle afr is fine,and your full load afr can come up into the high 12's-mid 13's so just change your main a little leaner.

UK Luke 72 Mon Mar 12, 2012 6:01 am

[email protected] wrote: http://www.thesamba.com/vw/forum/viewtopic.php?t=293837
I've managed 22pages of that John, I was hoping for a little more kadron specific advice.

UK Luke 72 Mon Mar 12, 2012 6:02 am

borninabus wrote:

kads use the same jets as PICT series carbs and the mains are also the same as mikuni motorcycle carbs.
you should be able to source something in country.

I did not know that! Should be able to come up with something here then!

UK Luke 72 Mon Mar 12, 2012 6:13 am

Does anybody have a pic of how high up the acc nozzle should be from the throttle plate? Or even better, a measurement?

I think from looking at kaddieshacks website I ought to go for the jets they recommend, at least if they're 'wrong' they will exchange for free.

andk5591 Mon Mar 12, 2012 6:27 am

You can just look down the carb as you bring up the idle to around 3000 RMPS and see what happens. Unfortnately I am about 1000 miles away from my cars, so I cant check - it was a matter of moving the nozzle up about 1/2" from where it was - but it may be fine already - Just fire up the car and look. If you need to adjust, make sure that you re-aim the nozzles.

As far as new jets go - I don't like trying something, then mailing them back and trying something else - When I am tuning, I just want to get done, which is why I have a fairly complete set. In your case, it would take quite a while and be pretty expensive having them sent back and forth across the pomd. And I am changing my suggestion - you dont really need the smaller jets (127s) - but I would go down to maybe 130 if you are ordering a few. Only drawback with places like AJ and Kaddie Shack is that the grind the numbers off the jets - which I personally dont like.

UK Luke 72 Mon Mar 12, 2012 7:42 am

Thanks andk! I'll have a look down the throat and also see what size mains I've got in there :)

krusher Mon Mar 12, 2012 10:04 am

I would shoot for 16/17 to 1 on the idle circuit, max mpg.

what distributor do you have?

UK Luke 72 Mon Mar 12, 2012 10:54 am

krusher wrote: I would shoot for 16/17 to 1 on the idle circuit, max mpg.

what distributor do you have?

Max mpg is good!
It's an svda

krusher Mon Mar 12, 2012 1:26 pm

Ok the SDVA is good the extra timing it pull matchs will with lean ldle circuit.

I would play around with some smaller idle jets, and watch carefully for pinging.

UK Luke 72 Tue Mar 13, 2012 5:42 am

krusher wrote: Ok the SDVA is good the extra timing it pull matchs will with lean ldle circuit.

I would play around with some smaller idle jets, and watch carefully for pinging.

So leaner idles and mains?
What size jets do the PICT series carbs use?

mharney Tue Mar 13, 2012 12:00 pm

What jets do you have currently?

To figure out what you need at light cruise, you need to know the jet sizes you have. If the idle jets are 55, changing to about a 50 or 52 would get you the right cruise AFR most likely.

example:

current AFR = 13
suppose target AFR = 15
suppose current jet is 55


(13/15) = (target jet * target jet)/(current jet * current jet)

So target jet = square root of ((13/15)/(current jet*current jet))

Target jet = 51.2

Since you are in transition state, or close to it, you might find that your results are a little off this but it is a guideline.

UK Luke 72 Thu Apr 05, 2012 12:08 pm

Ok so it's been a while, I've had chance to whip the lid off the carbs and they already have 130's in, I'm now trying to source 127's. The two junk 34PICT's have got 120's in which will be way too lean I think...
Did any PICT's come with 127's or should I be looking for even smaller still?

Much appreciated :)

AlteWagen Thu Apr 05, 2012 12:20 pm

Just get yourself a jet reamer kit and open up those 120s to the exact size you need

808OvalGreasemonkey Thu Apr 05, 2012 2:07 pm

IMO trying to run a old aircooled VW motor like a modern FI motor will get you hotter running and hesitation everywhere.
I realised when WB tuning my 2110 with 44IDF's that when I got the cruise afr into the 15's it had a noticable stumble with light throttle application (unless you stab the throttle to bring in the accel pump jet),which was not the best for running,not to mention higher oil/engine temps. I realised that old aircooled motors like to run a little rich and it gives me smoother running and sure Imay be spending a few PENNIES more on fuel,but my car isn;t stumbling on light throttle transition and running hotter than need be.
If you have lean afr at cruise,you will get higher EGT under a light load,I have tuned many cars with standalone EFI and this holds true for VW's as well.
ACVW does not have as much thermal efficiency as a watercooled car,so you have a smaller margin for error,that is why I would recomend runnig a little richer,since it is NOT a modern EFI car with close loop EFI,the richer mixtre will hep with any "holes" and your transitions will be better and cooler running.



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