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 tony_de_whitt
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| posted on April 6th, 2008 at 10:19 PM |
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carb balancing
Hello.
Has anyone got any hints or advice on balancing carbs.
Thabks in advance
anthony
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Dasdubber
A.k.a.: Alan Agyik
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| posted on April 7th, 2008 at 08:33 AM |
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Hi Tony,
Can you give us some more information re. which carbs you have and engine as well?
Cheers
Al
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tony_de_whitt
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| posted on April 7th, 2008 at 10:52 AM |
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The engine is an 1800, and they are the standard carbs for this engine. Solex. I can find exact model if required.
Thanks
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 Bizarre
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The artist formerly known as blue74l
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| posted on April 7th, 2008 at 12:08 PM |
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read the following and see what helps
This is the best link
http://www.clubvw.org.au/tuning_tips_for_tips_twin_carb_k.htm
There is a heap of links here - look under carburettors
http://www.type2.com/library/library.htm
click here might save some time - under FUEL
http://www.type2.com/library/fuel.htm
this is more general
http://www.aircooled.net/gnrlsite/resource/articles/dualcarb.htm
Futue te ipsum!!!
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tony_de_whitt
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| posted on April 8th, 2008 at 09:09 PM |
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thanks.
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aggri1
A.k.a.: Aurel Griesser
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| posted on April 10th, 2008 at 09:25 AM |
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| Quote: | Originally
posted by tony_de_whitt
The engine is an 1800, and they are the standard carbs for this engine. Solex. I can find exact model if required.
Thanks
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Oh. Yeah I got those. What a pain in the backside. Wish I had the FI model.
I found that making sure they were opening together was most of the problem most of the time. But of course all the linkages are worn and sloppy, so
it's a fiddly thing to do. Make sure the chokes are chocked open, I used screwdrivers, while synchronising the opening action.
I was going to construct a basic differential manometer to hook onto the brake booster elbow ports, for measuring relative vacuum difference, but I am
not sure this would work (but the vacuum there IS from below the throttle, so should be OK I think). I haven't done it yet. Would be a basic thing
with a few bottles and some clear tubing, nice and simple. Sorry I can't help more. This is one thing I usually let the mechanics do. Sometimes they
even get it right.
Cheers, A.
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mnsKmobi
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| posted on April 10th, 2008 at 12:50 PM |
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| Quote: | Originally
posted by aggri1
| Quote: | Originally
posted by tony_de_whitt
The engine is an 1800, and they are the standard carbs for this engine. Solex. I can find exact model if required.
Thanks
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Oh. Yeah I got those. What a pain in the backside. Wish I had the FI model.
I found that making sure they were opening together was most of the problem most of the time. But of course all the linkages are worn and sloppy, so
it's a fiddly thing to do. Make sure the chokes are chocked open, I used screwdrivers, while synchronising the opening action.
I was going to construct a basic differential manometer to hook onto the brake booster elbow ports, for measuring relative vacuum difference, but I am
not sure this would work (but the vacuum there IS from below the throttle, so should be OK I think). I haven't done it yet. Would be a basic thing
with a few bottles and some clear tubing, nice and simple. Sorry I can't help more. This is one thing I usually let the mechanics do. Sometimes they
even get it right.
Cheers, A.
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What about using a flowmeter? Or two if you're cashed up! 
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PurpleT3
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| posted on April 10th, 2008 at 01:32 PM |
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Use a carb synchroniser - the "snail" type. They are not that expensive. I would only use one and move it back and forth between carbs. I say
this as they are not the most precise instrument and different ones would probably read differently. It is the difference between the two sides that
you want to measure and balance.
Ain't nothin' like the wind in your hair.
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General_Failure
A.k.a.: Tristan
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| posted on April 16th, 2008 at 01:42 PM |
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Thanks for the links Bizarre!
I had completely forgot about the ClubVW walkthrough for carby balancing. I used to be a member of that club until I moved away.
Anyway I have the same problem with my 1800 dualcarb. Nightmare setup.
Not intending this to be a derail, just a general comment. As some of you may know I've been chasing a vacuum leak that I just can't find. After
reading this thread I had a revelation. For the van to idle, the air bypass screw is set so that a nightmarish howl comes from the idle throat when
the L pipe is off. It's very loud even sitting in the drivers seat with the hatch closed. Anyway my point is high airflow at low revs = low vacuum.
So after I test the brake booster for leaks, which I haven't done yet because I need to get hose to make blanks, I'm going to tackle the idle
circuits again.
I mirror the sentiment of wishing my van had EFI.
If at first you don't succeed. Build, build again.
Vehicle: 1975 Special order delivery walkthrough panel based LCA pop-top camper. Motor: Nippon 1.8L Single port Wasserboxer, Transmission: 3 rib 002.
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General_Failure
A.k.a.: Tristan
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Use your head, don't abuse it!
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Mood: Not too bad. Thanks for asking!
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| posted on April 19th, 2008 at 09:49 AM |
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I know it's a second post, but it seemed to make more sense than editing.
While the first article on tuning the carbs http://www.clubvw.org.au/tuning_tips_for_tips_twin_carb_k.htm is great there is an issue I can see. Plugging the idle throat and
disconnecting the solenoid have two very different effects which can influence tuning.
Disconnecting the solenoid will cause the motor to be tuned for the airflow, which I guess is fine because the aim is to get it idling at about 500RPM
with that idle circuit disabled.
Plugging the throat however will cause the mix to be off because it is being tuned for a lower airflow than the motor will normally experience.
I had a bit of fun with both methods yesterday messing with the van. I decided to check the initial mixture screws which I previously decided never to
touch. Glad I did. I don't remember the setting on the left carb. I know it was really wrong though. And the right one was wound in tight!
After adjusting to the suggested starting point of 2.5 turns, and messing with the air bypass screw to get the revs back down and thankfully stop the
horrific banshee howl from the idle throat I tried both idle crippling methods.
Disconnecting the solenoid caused the engine to stop instantly.
Plugging the throat with my finger, which I was no longer scared to do because the airflow is now sane, yielded a drop to what sounded like 500RPM. I
couldn't see the tacho at the time. Trouble is after a few seconds it went back up to about 1200RPM. Then I took my finger off and the motor
floundered and died.
Anyway, the point of that little story is that depending on what is up with the carbies, the two methods which are almost considered interchangeable
in the article have two very different effects.
If at first you don't succeed. Build, build again.
Vehicle: 1975 Special order delivery walkthrough panel based LCA pop-top camper. Motor: Nippon 1.8L Single port Wasserboxer, Transmission: 3 rib 002.
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