Timing for an 009 Distributor
dg...@hotmail.com
Its a dual port, universal case. Right now its close to 25 deg. PTDC,
but hesitates alot...but, its not pinging. And yes, I adjust my
valves every 1500 miles. Thanks for the help.
dave
Do you mean post or pre TDC? Stock engine?
I think you should use a light and check the total advance of the distributor
and set it at about 28 up to 32 degrees Before Top Dead Center.
Static might be 7 or 10 degrees BTDC.
read here about the 009
http://www.aircooled.net/gnrlsite/resource/articles/distributor.htm
got an airplane? read here
http://www.greatplainsas.com/itimingdisc.html
Someone correct me if I am wrong. And I hope you have a manual transmission
and your carb is working correctly.
later,
dave
Reminder........
Before you criticize someone, you should walk a mile in their shoes. That way,
when you criticize them, you are a mile away from them, and you have their
shoes. Frieda Norris
Masqqqqqqq
I dunno...i've got a 009 on a '71 super 1600 dp with the autostick. Works
pretty good.
Rob
I just happen to be editing the lengthy article on my web site about
009s, so here's a reprint.
VW built a lot of industrial engines (called type 122 for the 1200 and
124 for the 1600) as well as those engines built for the road going
vehicles like the type1 Beetles, type2 (Kombi/bus), type3 (Notchback,
Fastback, Squareback) and type4 (VW411, VW412) .
Industrial engines powering generators, compressors and such are near
enough to constant speed, so only a simple distributor was needed. So
a centrifugal distributor was developed by VW, and later by Bosch.
This type of distributor increases the amount of advance as the engine
speed rises, but can not sense the throttle position (engine load).
This is fine for engines operating at constant speeds, or at high
power and high rpm (for VW racing engines for example), plus the
previously mentioned industrial engines.
When the first type2 (Kombi etc) vehicles came out (around 1954), they
used the 1200 VW engine and needed reduction hubs so that the tiny
engine could push a heavy vehicle (with a top speed of about 85kmh
since the reduction hubs meant it was revving it's heart out!).
Because these engines in the type2 were working at high rpm and high
throttle most of their life, the VW version of the centrifugal
distributor was used on them too (but just try getting one off the
line - they needed a lot of revs and clutch slip to avoid bogging
down).
Most engines in road vehicles operate at various engine rpm and load
conditions, which requires a lot of variation in the amount of advance
needed for optimum engine performance and economy. Ideally, the amount
of advance varies from about 7 degrees to about 42 degrees, depending
on the engine model and it's intended use.
So most road vehicles use vacuum sensing, or a combination of vacuum
and centrifugal, to get the best timing over a wide range of engine
operations - low throttle low rpm, low throttle high rpm, high
throttle high rpm and every variation in between.
The early beetles used single vacuum single advance distributors
(SVSA); Then in 1971 they introduced the double advance technique -
using both rpm related and vacuum related advance. The first US
models of this distributor was the 71-73 double vacuum distributor (to
try to meet emissions requirements) called the DVDA - in other parts
fo the world is was a single advance double distributor (SVDA); and
from 74 onwards the US also went to the SVDA. The SVDA distributor
works like a high quality 009 with added vacuum advance.
These distributors are quite expensive to build in comparison with the
Bosch 009 (the Bosch equivalent of the VW centrifugal distributor).
So the cheap-to-build Bosch 009 became the "one size fits all"
replacement distributor, since it IS so cheap, and it does work
(moderately well). But precisely because it's a "one size fits all"
distributor, so it's NOT ideal for most engines, and it can cause
problems for some engine/carby set-ups.
To accelerate an engine smoothly, you need both extra fuel and an
extra advance. The accelerator pump provides the extra fuel and the
vacuum distributors provide the additional advance needed. But a 009
cannot provide any advance until AFTER the engine rpm starts to
increase (the advance starts happening at around 1200-1300rpm) so, if
the carby is set to run a little lean (LESS fuel), you get a
hesitation or flat spot, which usually means the driver has to blip
the throttle a time or two to get the rpm up to the point where the
009 is starting to advance, then "feather" the throttle (and slip the
clutch) so the rpm stays high, to avoid that flat spot.
The most common technique to overcome the 009 flat spot is to replace
that "missing" advance with extra fuel - a larger main jet, max stroke
on the accelerator pump, and in some cases filling in the air-bleed
hole in the throttle butterfly. By running the engine richer than
normal throughout it's operations, the flat spot is minimised.
The earlier Solex carburettors (28PCI, 28PICT and 30PICT/1 and /2) are
set to run a little on the rich side - the VW engine actually likes
around 13.8:1 air/fuel ratio, where the ideal is 14.5:1). So since
these carbies are set to run rich anyway, the flat spot is often not
noticable, or can be tuned out with minor adjustments.
But in 1970/71 the emissions problem was becoming recognised and VW
changed the jetting on the 30PICT/3 (1970 US only) and the 34PICT/3,
and /4 to run the carby leaner - closer to the ideal 14.5:1 air/fuel
ratio (the California 34PICT/4 uses especially lean jetting and a
throttle positioner to ensure the throttle closed slowly after you
lifted your foot off the pedal).
So with this leaner running carby set-up, the 009 flat spot becomes a
real issue.
You'll hear most complaints from folks who use the 34PICT/3, 34PICT/4
or the modern equivalent of the smaller carbs - the Brosol H30/31
(which is almost identical to the 1970 30PICT/3) - all of which
normally come delivered with lean jetting.
Another issue with the 009 is the limited maximum advance. The vacuum
distributors can run up to about 40-42 degrees under the right
conditions (light throttle and medium speeds for example) and this
helps fuel economy. But if you maintained that much advance with a
full throttle and low/medium rpm, the engine would ping/detonate, a
problem which can destroy and engine if left unchanged. The reason is
rather technical, but is mainly related to the amount of residual
exhaust gases which are left in the cylinder compared to the incoming
charge. There is always SOME residual gases, since there's a head
space above the piston. At part throttle there is a proportionally
larger amount of burned gases in comparison to the fresh stuff
(throttled fresh mixture but same head space of burned gases) - at
full throttle there's a lower proportion of burned gases because you
are letting in MORE fresh mixture for the fixed volume of head space.
This "contamination" of the fresh mixture alters the flame speed (the
time it takes for the fuel/air mixture to burn) so open-throttle needs
less advance (burns faster) and part-throttle needs more advance
(burns slower) - at any particular rpm.
Incidentally, this is part of the reason why the low compression 1200s
need more advance - usually 10BTDC compared to 7.5 BTDC for most
1500/1600s). Low compression means more head space (compared to the
cylinder volume), and so there is more contamination of the fresh
charge throughout the rpm range and that means a little more advance
is needed so all the fuel is burned just as the piston starts it's
descent.
There is an rpm related issue too - as the engine rpm increases, the
spark needs to occur sooner (more advance) to make sure the maximum
pressure on the piston occurs just as it starts it's descent.
The vacuum distributor senses throttle position, so if you floor the
throttle at low-medium speeds, the distributor is able to "back off"
the advance until the engine speed catches up with the new throttle
position (slowly allowing the extra advance back in as the rpm/airflow
rises), but the 009 cant do this, so it HAS to be set to "worst case"
which is between 28 and 32 degrees at 25-2600rpm (which is why we set
the 009 at 3000rpm - to make sure that all the advance is present).
Since the 009 has been limited to 28-32 degrees compared to the vacuum
distributor's 40-42, it's actually UNDER-ADVANCED for a lot of driving
conditions, and this means worse fuel economy. And because you need
to set the carby to run rich to reduce the flat spots, fuel economy
sufferes even more.
Because the 009 is built very cheaply, the total amount of advance
varies from one unit to the next. This means that when setting the
009, it's important to set it at max rpm, not idle, since the max
advance is much more important for most engine conditions. Always use
as much of the 28-32 as the engine can take without pining/detonating,
as this will reduce any flat spots just a little, and also help fuel
economy just a little. If it still pings at 28 degrees, always use a
higher octane fuel, NEVER use less than 28 degrees because it means
the engine is seriously underadvanced at higher rpm and will run
hotter than it needs to.
In the heavier bodied Kombi/bus and Karmann Ghia vehicles, you might
need to limit the max advance to the 28-30 degree range - they are
less likely to tolerate the 32 degree maximum as they are driven with
more throttle to accelerate the heavier body.
Once you have determined the maximum advance which works well for your
009, you can then measure the idle advance (which will probably be
between 5 and 10 BTDC, but might be outside that range) and you can
then use THAT setting for THAT 009 to set it at idle or static if you
want to.
Never use less than 28 degrees - if the engine still pings under heavy
acceleration at 28 degrees, use a higer octane fuel. Using less than
28 degrees means that the engine will be underadvanced at higher rpm
and will run hotter than it needs to, and fuel economy will suffer
too.
So you can see that the 009 is NOT ideal, but it will work. For best
performance under all engine operating conditions, you need a vacuum
distributor.
Hope all that makes sense.
Probably more than you wanted to know!
Regards
Rob
Rob and Dave's aircooled VW pages
Repairs and maintenance for the home mechanic
http://www.geocities.com/aussiebug1970/
BergRace
J.
--
P.J.Berg.
"Rob" <aussie...@yahoo.com> wrote in message
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Joe Cali - Next Generation-USA
picked up a Mallory ledlite dizzy. Got great reviews on the dyno tests and
from the guys that have them. My 009 has worked for years but I know it
has many shortcomings.
Joe Cali Next Generation -USA
http://home.att.net/~nextgen
"BergRace" <Bo...@news.no> wrote in message
news:dXata.4949$KF1.89490@amstwist00...
dg...@hotmail.com
Thank you so much. Your explaination answered alot of other questions
I was getting ready to ask. Great replies. Thank you all.