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Sat Jul 04, 2009 3:21 pm

I have a 72 beetle with a 1600 DP a 34 pic 3 carb and an SVDA 034 dist.
My problem is getting a consistant idle. If I run down the road and warm it up then stop, as soon as I let off the gas the idle drops to about 1800 rpms then as I let it idle it slowly drops to 900 rpms. This takes about 30 seconds. Then as I let it idle it starts to speed up to about 1200rpm's then slowly starts dropping back to 900. It keeps doing this over and over. It will speed up and slow down by itlself. Does anyone have any ideas?

Sat Jul 04, 2009 3:29 pm

Do you have your throttle arm adjustment set up properly so that it is shut all the way, as per the carb adjustment procedure? (and is the throttle cable not binding or the like to prevent the throttle from shutting?) What variety of 34ICT-3 carb (German, Mexican, Brazil, etc)? How's the play in the throttle shaft bushings? Lastly, any intake vacuum leaks, at the rubber boots on the intake manifold or the heads?

-Andy

Sat Jul 04, 2009 3:34 pm

I redid all my carb adjustments and I think they are correct. This problem started after I replace the 009 dist. with the 034. I totally lost my flat spot but I have this new problem. Its a German carb.

Sat Jul 04, 2009 6:41 pm

Well, I'd doublecheck the throttle stop adjustment again, just to be sure (choke warmed up and backed off, loosen it until there's an air gap between it and the fast idle cam, then screw it in until it just contacts, plus a half a turn more in so it something to sit on instead of binding the the throttle shaft in the carb throat)

I'd also check the centrifugal advance that it's not at all sticky. The old 'wrist twist' on the rotor, plus looking at it with a timing light while running.

What's the base flange number on this German carb, by the way?

-Andy

Sun Jul 05, 2009 7:57 am

Flange number is 377-2. It looks like this carb is for a DVDA.

Sun Jul 05, 2009 8:10 am

Yes it is. Sometimes that 12 degrees advance in timing at idle throw such a carb way off, to the point where you have to have the air bypass screw all the way to the bottom trying to compensate, and the carb is no longer near a "sweet spot" for the idle setting.

Sun Jul 05, 2009 12:38 pm

Thanks for the info. I am going to try the pop rivet in the butterfly

Sun Jul 05, 2009 12:50 pm

burdpete wrote: Thanks for the info. I am going to try the pop rivet in the butterfly

do you mean your going to plug that hole in the throttle butterfly? thats the dumbest thing i have ever heard. check for vacuum leaks first and try re-tuning your carb before you do something as dumb as plugging a hole that was put there for a reason.

Sun Jul 05, 2009 12:56 pm

connella08 wrote: burdpete wrote: Thanks for the info. I am going to try the pop rivet in the butterfly

do you mean your going to plug that hole in the throttle butterfly? thats the dumbest thing i have ever heard. check for vacuum leaks first and try re-tuning your carb before you do something as dumb as plugging a hole that was put there for a reason.

It's not so dumb... it works...you don't "plug the hole" you just reduce it in size to the diameter of an SVDA flange # carb.

DUMB was the Mexican jumping beetle video! :lol: :wink:

Here's a thread on it...

http://www.thesamba.com/vw/forum/viewtopic.php?t=340069&highlight=dvda

Here is a follow up post.

2jmotorsports wrote:

I actually managed to get ahold of a couple of identical DVDA dizzies that are a close match to the original 71 bus dizzy, but they are in really bad shape and are in need of a rebuild to make 1 good complete one.

The SVDA that I currently have seems to be in good shape and although my carb was meant to work with a DVDA, I will try the rivet fix described here since it seems relatively easy:

http://www.thesamba.com/vw/forum/viewtopic.php?t=340069&highlight=dvda

If that doesnt cure the problem, then I will probably focus my attention back on the DVDA dizzy rebuild.

While I am at it I will look for any possible exhaust leaks as well.

Thank you for all the replies and I will report back soon with results.

2jmotorsports wrote:

Tried the rivet fix and my carb immediately became docile! Dialed in my idle and timing per spec in a matter of minutes. Thanks again for the help.

Sun Jul 05, 2009 6:00 pm

Put the pop rivet in this afternoon and it isnt even like its the same car. It runs and idles better than ever. Yesterday I spent 3 hours trying to tune the carb. Today I spent 2 minutes tuning after the pop rivet and it runs perfect. Dont ever doubt keifernet. He is the carb expert on The Samba!

Sun Jul 05, 2009 6:13 pm

burdpete wrote: Dont ever doubt keifernet. He is the carb expert on The Samba!

R=True Dat! He helped me tame my Bocar. I can dial in the idle by 10 RPM increments now.

Sun Jul 05, 2009 10:11 pm

I described the syndrome, I let Keith tell you how to fix it...! :D

I wasn't surprised at seeing the problem once I read what base-flange number you had... seen more than a couple of DVDA carbs just not want to dial in with a different distributor in the past.

-Andy

Mon Jul 06, 2009 3:56 pm

glutamodo wrote: I described the syndrome, I let Keith tell you how to fix it...! :D

I wasn't surprised at seeing the problem once I read what base-flange number you had... seen more than a couple of DVDA carbs just not want to dial in with a different distributor in the past.

-Andy
Yea I didnt mean to ignore you. You identified my problem right off the bat and I appreciate it. It was actually your post that started my searching for my flange #. I drove the bug to work today ( 40 miles RT) and it runs better than it ever has. I cant believe it. I am an old time small block chevy guy who just got schooled on VW's.
Thanks again for your help.

Mon Jul 06, 2009 4:40 pm

burdpete wrote: glutamodo wrote: I described the syndrome, I let Keith tell you how to fix it...! :D

I wasn't surprised at seeing the problem once I read what base-flange number you had... seen more than a couple of DVDA carbs just not want to dial in with a different distributor in the past.

-Andy
Yea I didnt mean to ignore you. You identified my problem right off the bat and I appreciate it. It was actually your post that started my searching for my flange #. I drove the bug to work today ( 40 miles RT) and it runs better than it ever has. I cant believe it. I am an old time small block chevy guy who just got schooled on VW's.
Thanks again for your help.

Say... didn't I PM you about flange #'s and the info about the same time! :? :lol: :wink:

I have learned a great deal from Andy and his posts myself... we trade PM
s about things all the time and so we are ( mostly) on the same page about a lot of things.

He's a great asset to the forum.

Mon Jul 06, 2009 4:59 pm

keifernet wrote: burdpete wrote: glutamodo wrote: I described the syndrome, I let Keith tell you how to fix it...! :D

I wasn't surprised at seeing the problem once I read what base-flange number you had... seen more than a couple of DVDA carbs just not want to dial in with a different distributor in the past.

-Andy
Yea I didn't mean to ignore you. You identified my problem right off the bat and I appreciate it. It was actually your post that started my searching for my flange #. I drove the bug to work today ( 40 miles RT) and it runs better than it ever has. I cant believe it. I am an old time small block chevy guy who just got schooled on VW's.
Thanks again for your help.

Say... didn't I PM you about flange #'s and the info about the same time! :? :lol: :wink:

I have learned a great deal from Andy and his posts myself... we trade PM
s about things all the time and so we are ( mostly) on the same page about a lot of things.

He's a great asset to the forum.

Yea you both helped. I quess what really humbled me was that I thought you were both nuts. I thought this might help my problem a little but what blew me away was that it totally solved it. I have a 30 year old degree in automechanics but I have learned VW's are different. Acually I was amazed at how sofisticated the carb was.I didnt expect that on a vehicle know for its economy. Another thing. Since I replaced the 009 with the 034 dist. my gas milage has gone from 28.5 to 31 MPG. And that was before I corrected the idle issue. Thanks Guys!

Tue Jul 07, 2009 8:58 am

Anyone know the diameter of the different size holes in the throttle plate on the 34 pict carbs.

Tue Jul 07, 2009 9:26 am

Gariack wrote: Anyone know the diameter of the different size holes in the throttle plate on the 34 pict carbs.

The DVDA is approx 5/32" and SVDA is 1/8".

Hard to believe that difference does anything but trust me... it makes a big difference in the way the carb runs/tunes when your using a DVDA flange # German carb meant to be timed at 5 ATDC with an SVDA timed at 7.5 or an 009 timed at 10 BTDC.

I find the pop rivet easier than taking the plate out and soldering the hole shut, grinding it flush and re drilling it but that's a personal choice. It can also be "undone" in a matter of minutes if someone wants to go back to a DVDA and does not alter the carb in any other way.

Tue Jul 07, 2009 9:58 am

Thanks Keith that is exactly what I was looking for.

Tue Jul 07, 2009 9:59 am

Keith,

Is there a punchlist of flange ## to applications? This is something I didn't check when you helped me dial in my Solex about 18 months ago, and I AM running DVDA. (though the state of the diaphram is unknown.)

M

Tue Jul 07, 2009 10:07 am

webwalker wrote: Keith,

Is there a punchlist of flange ## to applications? This is something I didn't check when you helped me dial in my Solex about 18 months ago, and I AM running DVDA. (though the state of the diaphram is unknown.)

M

Andy has posted various charts many times. Here's one with just 34 pict 3 German info.

I probably asked you when I built your carb what distributor your running.

If you need some help with it just PM or email me.