Solex 34 pict 3 flat spot

Peter Kwentus

unread,

Feb 15, 1995, 8:19:24 PM2/15/95

to

I have a 71 super beetle 'vert which I have restored from the groud up.
When it came time to rebuild the engine, I added a bosch 009 distrib. and
kept the stock carb. (The 009 has no vacume advance) I have noticed that
there is a noticeable flat spot between the low and high engine ranges.
The carb is immacuatly cleen and my timing is correct. I've also noticed
that when braking heavily, the engine has a tendancy to stall. I've
noticed a similar problem in my friends Ghia with an identical
carb/distrib combo. Any suggestions?

Pete Kwentus
'71 super beetle 'vert

Frank Klein

unread,

Feb 15, 1995, 11:14:28 PM2/15/95

to

Peter Kwentus (pkwe...@saucer.cc.umr.edu) wrote:

: I have a 71 super beetle 'vert which I have restored from the groud up.

You have discovered the famous 009/34 PICT-3 flat spot. It's typical...
on the mailing list, this topic has come up, and quite a few people have
complained about it.

One of the list subscribers suggests that the flat-spot is a sign of marginal
carburetion. With the 34 PICT-3, this is a normal condition... some of the
vehicles with these smog-carbs had flat spots stock.

There was a suggestion that drilling out the hole in the throttle plate might
reduce the flat-spot, but I do not know.

When I had a 009 and 34 PICT-3, I never noticed it... if you always floor
the throttle, you won't notice it either ;)

Frank

--------------------------------------------------------------------------------
Frank Klein a.k.a. fkl...@orion.csci.csusb.edu Cal State Univ San Bernardino
et...@cleveland.freenet.edu +------------------
"Best car ever made: VW Beetle" -- Automobile Magazine | '72 Super Beetle
Any opinions expressed are the correct ones. | '90 cat
-------------------------------------------------------------+------------------

John M. Bilek

unread,

Feb 17, 1995, 1:44:17 AM2/17/95

to

Peter Kwentus (pkwe...@saucer.cc.umr.edu) wrote:

: I have a 71 super beetle 'vert which I have restored from the groud up.

: When it came time to rebuild the engine, I added a bosch 009 distrib. and
: kept the stock carb. (The 009 has no vacume advance) I have noticed that
: there is a noticeable flat spot between the low and high engine ranges.

I'm sure you'll get a lot of responses on this. The 009 and 34pict3 are
nopt really compatable. Something having to do with the advance curve to
fuel curve blah, blah, blah. I have heard many, many people both
personally and on the VintagVW mailing list that complain of the infamous
"flat spot" with the 009/34pict3 combination. I don't know what the fix
is (Frank K., you out there?)...Maybe a re-jetting thing?

--
Johnny.

john...@netcom.com
john...@aol.com

Stefan Frick

unread,

Feb 17, 1995, 6:38:28 AM2/17/95

to

In article 1...@nic-nac.CSU.net, fkl...@silicon.csci.csusb.edu (Frank Klein) writes:
>Peter Kwentus (pkwe...@saucer.cc.umr.edu) wrote:
>
>: I have a 71 super beetle 'vert which I have restored from the groud up.
>: When it came time to rebuild the engine, I added a bosch 009 distrib. and
>: kept the stock carb. (The 009 has no vacume advance) I have noticed that
>: there is a noticeable flat spot between the low and high engine ranges.
>: The carb is immacuatly cleen and my timing is correct. I've also noticed
>: that when braking heavily, the engine has a tendancy to stall. I've
>: noticed a similar problem in my friends Ghia with an identical
>: carb/distrib combo. Any suggestions?
>
>You have discovered the famous 009/34 PICT-3 flat spot. It's typical...
>on the mailing list, this topic has come up, and quite a few people have
>complained about it.
>
>One of the list subscribers suggests that the flat-spot is a sign of marginal
>carburetion. With the 34 PICT-3, this is a normal condition... some of the
>vehicles with these smog-carbs had flat spots stock.
>
>There was a suggestion that drilling out the hole in the throttle plate might
>reduce the flat-spot, but I do not know.
>
>When I had a 009 and 34 PICT-3, I never noticed it... if you always floor
>the throttle, you won't notice it either ;)
>
>Frank
>

If I'm not mistaken I think HotVW's (or was it VW Trends?) had an article in
one of the -94 issues about this. The only thing I can remember right now
was that they drilled the acc.jet with a 0.050" (1.27mm). Also make sure
the nozzle points to the edge of the butterfly, not to the center.
I'll check this when I get home, be back on moday!

Richard Bjornson

unread,

Feb 17, 1995, 10:49:04 AM2/17/95

to

Stefan Frick (etx...@helix.ericsson.se) wrote:

: In article 1...@nic-nac.CSU.net, fkl...@silicon.csci.csusb.edu (Frank Klein) writes:
: >Peter Kwentus (pkwe...@saucer.cc.umr.edu) wrote:
: >
: >: I have a 71 super beetle 'vert which I have restored from the groud up.
: >: When it came time to rebuild the engine, I added a bosch 009 distrib. and
: >: kept the stock carb. (The 009 has no vacume advance) I have noticed that
: >: there is a noticeable flat spot between the low and high engine ranges.
: >: The carb is immacuatly cleen and my timing is correct. I've also noticed
: >: that when braking heavily, the engine has a tendancy to stall. I've
: >: noticed a similar problem in my friends Ghia with an identical
: >: carb/distrib combo. Any suggestions?

-<snip>-

Dual carbs will rectify the situation also...

Mdberry

unread,

Feb 19, 1995, 1:34:00 PM2/19/95

to

Hot VWs did do an artical on drilling the accelerator pump jet. You also
have to drill the hose (as well as aim it to the edge of the
butterfly-that makes a big difference). DON'T drill a hole in the
butterfly as someone else mentioned. You drill the accelerator circuit to
give it a richer mixture when you stomp the throttle.

MDB

Stefan Frick

unread,

Feb 20, 1995, 8:11:33 AM2/20/95

to

Did some 'research' during the weekend :)

The March -93 issue of Hot VW's had an article called 'Troubleshooting the
Solex 34PICT-3" Since it clearly says "Reprinting in whole or part, expressly
forbidden....", I cannot retype the article. However, back issues can surely
be ordered from Hot VW's.

Anyway, they had a 34PICT-3 on one of their project cars, a 1776cc with a 009
distributor. The jet sizes were: Main 135, Idle 65, Aux 50 and Accel.pump 50

The Aux and Acc.pump jetsizes were drilled to the correct diameter using a 0.050"
drill (1.27mm)

The article also mentions a common mistake, adjusting the idle speed by turning
in the small screw on the linkage arm. This (of course...) raises the butterfly
up and will expose the progression circuit holes in the bottom of of the throttle
bore. This means that the carb can't properly pass from the idle to the progression
circuit, and a flat spot will occur.

They also discovered that the stock (vaccuum) distributor had a very quick advance
curve rate when throttle was applied, and that the 34PICT-3 seemed to require this
to compensate for a lean spot. When the 009 was installed with a timing of 26-28
deg. of total advance, a low speed flat spot occured. What they did was to:

A: Enlarge the acc.jet in the nozzle with a 0.050" drill

B: Adjust the lever to the acc.pump (The good 'ol "trial and Error" method...)

C: Position the acc.pump nozzle to point exactly to the edge of the butterfly

D: Enlarge the aux. jet to 0.050"

According to the article they managed to get the carb not only work, but to work
well! The article also contains a lot of photos, you know "A picture can tell
more than thousand words..."

I have not tried the above myself, but as I'm currently rebuilding my -73 Super
Beetle (and plan to fit 1835cc cylinders), I will for sure do that when the day comes.
Not all of us can afford to fit dual Webers/Dellortos etc...

Good luck!

-Stefan

Ps. The address for ordering back issues of Hot VW's is:

DB&HVWs Back Issue Department
PO Box 2260, Costa Mesa, CA 92628
(USA)

Irwin M. Fletcher

unread,

Feb 20, 1995, 8:24:50 PM2/20/95

to

From what understand you can develop a big flat spot when running this carb along with the 009 distributor. Read about this is some VW book of some sort at
my house over break.