Rivet Carb Solution and a Really Low Idle

[CarlSpackler]

I've been through a bunch of posts about the 34-pict 3/4 carb flat spot with an 009 distributor. I put a rivet in the butterfly as suggested / recommended by a number of folks (also discouraged by a number of folks), and it fixed my flat spot. However, my car now idles at about 400 rpm. I've followed the standard instructions for adjusting idle and seen no change. I'm thinking the next thing I'll do is back the smaller screw out well past the recommended 2-3 turns from bottom, but thought I'd drop this question here, too. Anyone else have this effect? I found it really odd that it had that dramatic an effect, but no one has mentioned it.
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'67 Micro Bus
'73 Thing
'91 Westy

[TDCTDI]

So.... you plug a “calibrated air leak” & wonder why it affected your idle?
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Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


GOFUNDYOURSELF, quit asking everyone to do it for you!


An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.

[kpf]

Follow this procedure for tuning the carburetor: http://www.vw-resource.com/34pict3.html
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1971 Super Beetle

[CarlSpackler]

Yep, those are the instructions I've been following.

Calibrated for a different dizzy - thus working to recalibrate for an 009.

Helpful responses are welcomed and appreciated. Others need not participate. You're wasting your time and the time of anyone else who might benefit from this (or any) post in the future, which is the supposed to be the point of thesamba.com.
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'67 Micro Bus
'73 Thing
'91 Westy

[TDCTDI]

Sometimes, pointing out the fucking obvious is the most constructive.
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Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


GOFUNDYOURSELF, quit asking everyone to do it for you!


An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.

[kpf]

[TDCTDI]

[kpf]

LOL - Really? Will the rivet completely stop the bypass from getting any air at all?
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1971 Super Beetle

[TDCTDI]

[kpf]

Totally makes sense!
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1971 Super Beetle

[CarlSpackler]

I've removed the rivet and returned to the same condition I had previously: Wonderful idle but a challenging flat spot. However, I've learned that the issue might be a problem with the carb as opening neither screw made any difference with the hole plugged by the rivet.

Thus, the value of the exercise. Try "tweaking" the parts to get a better result. I would have been disinclined to modify a well-functioning set up. But most of us know how poor the quality is on new parts, and this carb has maybe 10 hours on it.
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'67 Micro Bus
'73 Thing
'91 Westy

[TDCTDI]

The main problem that you are having is that you’re trying to correct a timing issue with tweaks/adjustments of the carburetor.


Shit can the 009 & put the correct BOSCH SVDA distributor back in & your drivability issue will go away. (Or learn the “pat the accelerator three times as you slip the clutch” method.)


The 009 was made to be used on stationary engines, the lack of a vacuum advance really hinders the performance when installed on a road going car. They were the “performance” go to when putting on dual carbs or vehicles with bigger cams that altered the vacuum “signal”.


There are a few members here that rebuild & sell Bosch distributors. Glenn come to mind.


In my youth, I destroyed the drivability of many a decent running VW by bolting on all of the “high performance” goodies of the day & then went to water pumpers for a couple decades because I didn’t have to constantly screw with them when most of the drivability issues were caused by shit that I did.


And, well... due to a previous owner’s determination to stuff a fucking rivet into every hole he could find, I’m a bit disgusted by rivets at the moment.
_________________
Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


GOFUNDYOURSELF, quit asking everyone to do it for you!


An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.

[perello]

my personal experience here, is that I am kind of stubborn using a german 009 (against all odds)

During years I've been tweaking the carb to minimize the infamous flat-spot..but never get rid of it...the world was right and I was wrong.


Until I put this

and suddenly flat spot is gone. No more carb tweaking...right idle, right CO level 1.2% at idle.
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Aug '58 pressed bumper SO23
1974 German Thing
1978 Bug 1200

[Wildthings]

The rivet helps bring the idle down without throwing the rest of the carb out of balance, it is used when the vacuum retard is can dies, and should make it so the base throttle plate adjustment and the bypass work fine. I did it on my 34-3 with a SVDA and the idle speed ended up fine with no flat spot. Can't say how it would work in conjunction with an 009, especially some cheap clone.

The bypass is like a miniature carburetor attached in parallel to the main one. It has both a volume adjustment and a mixture adjustment, so you should be able to select the proper volume of both air and fuel to get an excellent idle.

Make sure your timing is in the 28-32° BTDC @3800+ rpms, with any hoses removed and plugged.

[Wildthings]

The rivet is to combat the high idle one gets when the vacuum retard fails or is eliminated. Without the rivet there may not be enough range in the idle bypass system to get the idle speed down to where you want it without causing a lag coming off idle. Tuning the idle with an 009 and a SVDA shouldn't be a lot different if the idle timing is the same for both. I would time both in the 28-32° BTDC @3800+ rpms, with the any hoses removed and plugged. You need to make sure the base adjustment for the throttle plate is correct and that everything about the idle bypass system is correct, it is possible you might want to use a different idle jet from what you now have.