Kombi Fast idle adjustment

Kommer Casual Dubber

45 posts · joined Apr 2004 · 4 Apr 2005, 7:21 pm

#330010

My 1800/2000 aircooled Kombi runs too fast when the automatic chokes are on, which is bad for a person who is usually pretty keen on warming it up before driving.

I checked the Bentley manual and set the carbs up to the right specs with .028" clearance on the throttle butterflys with the chokes fully closed, but it still ran much too fast. So I backed off the chokes and turned the nuts on the fast idle operating rods down a couple of turns on each side which has slowed it down a bit, but it's still not right.

I hate having the carbs not set up by the book. Does anyone have any ideas as to what would make them act up like this ?

Thanks,

Martin

[Edited on 4/4/2005 by Kommer]

Kommer Casual Dubber

45 posts · joined Apr 2004 · 6 Apr 2005, 6:36 am

#330893

No ideas ???

helbus Administrator Mad fabricator, paint and body

7,386 posts · joined Sep 2002 · 6 Apr 2005, 9:04 am

#330947

It should idle fast on auto choke, and the revs usually get higher as it warms up until you 'kick' them off.

Could also be a worn distributor.

EJ22 into Bay Microbus - Finished project build thread- click on this spot here for info

Andy Andy\'s Adventures

2,820 posts · joined Nov 2002 · 6 Apr 2005, 11:59 am

#331052

Kommer wrote:............ So I backed off the chokes and turned the nuts on the fast idle operating rods down a couple of turns on each side which has slowed it down a bit, but it's still not right................................
Martin

Stock setup has this very fast idle speed on most auto choke Solex's for VW's. What I do is set throttle butterfly + choke as per Bently, this is the best set-up. Also set the central idle circuit as per Bently for the correct rpm at idle when hot.
Next, like you I adjust the nuts on the "fast idle operating rods". I find I have to turn them back quite a lot from spec. (on carbs still with factory setting and paint).
I find Andy (2L dual carb) will happily idle ~1000-1200rpm from cold on choke, winter or summer. Then he gets to warm up at a nice slow pace. 😉
So, sounds like you've done the right thing, just adjust the nuts on the rod a little more, and make sure the rest is to spec.
Just remember setting this low means the motor is less tolerant if anything get's out of tune.

68AutoBug Beetle Restorer - Experience over 138\% - YIKES --

11,654 posts · joined Aug 2002 · 6 Apr 2005, 12:09 pm

#331058

Automatic chokes do tend to make Your engine race too much
I have found...
I have always found that auto chokes do need adjustment from time to time.. they area very basic item....

as they don't 'really' adjust for the ambient temperature...

When the engine's cold... the chokes ON...

I prefer to have the engine revving less.... when cold...
by adjusting the auto choke itself...

as someone else said, sometimes the revs don't drop as the choke heats up, due to the adjusting screw "sticking" on the stepped piece of the carby....
and NOT dropping down by itself...
You would have to touch the accelerator to get it to drop off... to normal idling speed....

Lee

- Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY---

Kommer Casual Dubber

45 posts · joined Apr 2004 · 6 Apr 2005, 12:20 pm

#331065

Thanks for your thoughts Andy and Lee.
I guess I'll drop the nuts down on the operating rods a little more and see how it goes.
How do you guys set up the chokes themselves ? All the manuals (Bentley, Haynes, Gregorys and of course Muir who is positively scathing about the auto chokes on Solexs) make no mention that I can see about setting up the round choke drum containing the bi-metal coil. I have always had the policy of positioning them so that when cold the choke butterfly is just closed. That means that as soon as the car is running (or even swithched on) they are moving towards open (or will if the accelerator is touched)
The Westy I have just bought had them set up the other way, so that when hot they are just fully open. I didn't like it that way because if you turn the car off to go into the shop or whatever and return in 10 mins the chokes are on and engine is revving.
It's strange that the manuals don't mention anything- or am I looking in the wroke place ?

Andy Andy\'s Adventures

2,820 posts · joined Nov 2002 · 6 Apr 2005, 12:37 pm

#331082

Hmm... Don't have manual handy, but most chokes have a line stamped on them which you turn to line up with a cast in high point on the body of the carb. In practice this normally means after they "just close" you will need to turn it a further ~1/4 turn or so.
Set this way they will work fine winter/summer. I usually set like you, until they only just close (depends on motor and tune it's in), but need a little tweaking come winter.

The operation of the choke from start up is the choke butterfly will gradually open regardless of whether you blip the throttle or not, but the fast idle setting on the throttle butterfly will not reset until you do, as Lee said.
The choke bi metal strip is heated only by the element in choke itself, so is really independant of whether the motor is hot or cold, that's why they will come back on quickly when you turn off.