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 Post subject: Weber 32/36 Conversion to a Gemini
PostPosted: Tue May 26, 2009 5:44 pm 
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Conversion of a Gemini engine to a Weber 32/ 36 is one of the most common modifications discussed on this website. I thought it might be a good idea to submit a thread that gives the basics of this modification and some links to some useful sites related to rebuild and tuning of this popular carburettor.

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So why do a conversion to a Weber 32/36?

• Performance? Slight improve over a Nikki but better fuel economy and easier to keep in tune.
• Maintenance. A 32/36 is a wonderfully simple and well made carburettor and you don’t get the spindle wear problems of the more complex and harder to service Nikki.
• Availability – plenty of these carburettors around and parts reasonably easy to come by.

A 32/36 is about the worlds easiest carburettor to rebuild and anyone can do it with a few basics tools and care in following the advice on some of the key linked sites I am suggesting below.

Helpful Places

I have put John Connolly’s jetting theory article first. An understanding of the three main fuel circuits/ systems in a carby (idle/progression, main jet, air jet) is really helpful

http://www.aircooled.net/gnrlsite/resou ... etting.htm

Dennis Hale’s article is widely referenced. It’s a good article but he starts with main jet sizing whereas I prefer to sort out the idle / progression system before the main – and he gets the DGAV meaning wrong

http://dimequarterly.tierranet.com/arti ... uning.html

This is a Link to Chris Reece’s site – the trouble shooting section of this site is the most useful bit. It looks like a lift from a Weber manual

http://www.jessies.org/~car/projects/carb/

Jetting Table – describes the factory jetting for the different Weber types. It will tell you if yours have been interchanged or whether they are factory set.

http://www.gracieland.org/cars/techtalk/weboem.html

Nice simple exploded diagram but…

http://www.gowerlee.dircon.co.uk/DGAVtype.html

.. the Redline Weber tech section has more detailed explode diagram, parts list and idle tuning tips

http://www.redlineweber.com/html/Tech/T ... ntents.htm

Some good picks and small engine jet sizes

http://www.izook.com/tech/samurai/engin ... /weber.htm

Idle adjustment and selecting an idle jet size

http://www.carburetion.com/Weber/adjust.htm

Choosing Weber

The Weber 32/36 were produced as:

• DGV - a manual choke model
• DGAV – water choke model
• DGEV – Electric choke model
• DFV – mirror version of a DGV – rarer, but some prefer it for Gemini application

The big brother is the 38 DGES and the cousin is the 34 ADM.

Image

Note the 38DGES left has the extra idle tuning screw in the base.

Image

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Top section of the 32/36 and 38 almost identical.

The 32/36 is a two barrel carburettor has a 32 mm barrel that operates at low speed and a 36mm barrel that manually operates at ¾ throttle. A 34 ADM operates the same way and has two 34 mm barrels. A 38 DGES has two 38 mm barrels that are synchronised to open at the same time.

The standard Nikki is a two barrel carby also but relies on vacuum / air flow as well as a mechanical link to operate the second barrel at high revs – and it often doesn’t work too well. With a Weber – put your foot down and it happens.

The 34 ADM is commonly sourced from old Ford Falcons and re jetted. I’m not a fan because the 34 ADM is an emission control carburettors while the 32/36 is a pre emission carby. There are forum members who have successfully adapted the 34 ADM carburettors.

A lot of people remove the cold start choke mechanisms from DGAV and DGEV 32/36 carburettors to make the accelerator cable adaption a bit easier. I like to keep the electric choke because it works brilliantly. The DGAV water choke can be easily converted to an electric choke – more on that later.

Image

Preparing Your Weber

First job is to find out what you have. Remove the top cover (taking care to unclip the choke link) and check the sizes stamped on the following bits and write them down for later reference:

• Main jets
• Air correction jets

Unscrew the air correction jets and note the marking on each

• e-tube

Unscrew the idle jet holders and note the size of the:

• Idle jets

Remove and check the

• pump jet

Image

It is highly recommended that you put a kit through the carby – replacing the needle and seat, gaskets and “O” rings.

Image

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The links above will provide an exploded view and parts list for your model. When you disassemble the 32/36 it is not advisable to remove the butterflies from the spindle as the screws are a one-time use and will tend to strip when removed. Unless the nylon spindle shaft bushes need replacing – leave it alone.

Use screw drivers that exactly fit the screw slots. If the e-tubes get stuck try to hook them out with a piece of wire after a liberal soak with WD40.

Use two trays – one for your dirty parts and one for your clean parts and don’t but the trays where your dumb mate will kick it all over the shed (bitter experience talking here).

Cleaning

A wash in clean petrol using a tooth brush is normally sufficient. Then blow through the galleries and jets with compressed air. If you have some lacquer thinners repeat the wash and you will lift off most of the stubborn black staining.

Blow out the galleries again.

Warning –
• Wear eye protection – splashing petrol in you eye is bad, thinners real bad and possibly permanently damaging.
• Work in a well ventilated area and f%#k sake don’t smoke.
• Wear gloves – OK so you will probably ignore that for petrol but seriously skin contact with thinners is bad news.

Reassemble with your new kit bits. Check the diaphragm on the power valve (in the top cover) and the diaphragm in the choke pull-off. These can be purchased separately if damaged.

The only mildly tricky bit is setting the float level and that is described in the links.
All finished, sit back have a beer, admire your work and toast how clever you are.

More in the next instalment……


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 Post subject:
PostPosted: Wed May 27, 2009 1:25 pm 
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Manifold Preparation

With the carby sitting clean on the bench, time to think about the manifold.

The Nikki and Weber are not interchangeable directly because the base of the Weber is wider. So you need an adaptor plate like the Redline adaptor pictured. Pretty readily available at Autobarn.

Image


The basic conversion if the remove the Nikki. Remove the 4 studs that hold the carby to the manifold. Check which way round the adaptor goes for your Weber (it will be different for a DGV compared to a DFV) so that the smaller opening end lines up with the 32mm butterfly and the wider opening lines up with the 36mm butterfly.

Image

Fit the bottom gasket, long studs, hex bolts and short studs top gasket, insulation block (optional, if you have one) and carby

Image

Basically that will do it but if the manifold is off the motor you can have a play with improving the flow by cutting the manifold to match the adaptor – taking care not to damage the face of the manifold where the gasket sits.

Bolt the adaptor in place, scratch the outline of the area to be removed with the edge of a small screwdriver. Remove the studs and bolts. I find a jig saw and a light touch works well to remove the excess material.


If you have a die grinder and aluminium cutting head you can really go to town. I port out the opening a bit without the adaptor in place then bolt down the adaptor and smooth out the transition area between the manifold and the adaptor. You can’t get too carried away because the lip face where the nmanifold mates to the adaptor is pretty thin on 3 sides.
Image

Before attacking with the die grinder, knock the vacuum pipes just inside the manifold out so they are level with the inner manifold face – that will avoid their complete destruction. Knock them back in when your done.


(Stud removal for novices – fit two nuts to the stud. Turn the bottom one anti clockwise and the top one clockwise and lock them hard together – like really tight. Unscrew the stud from the manifold using the bottom nut. Unlock the two nuts)


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 Post subject:
PostPosted: Wed May 27, 2009 5:49 pm 
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Plumbing

The Nikki and a lot of other carburettors use a “banjo” arrangement to affect connection of the fuel line to the carburettor body and feed the needle and seat. So do a number of other carburettors including Weber DCOE and Dellorto DHLA. The “bango” can have just a single inlet pipe or a second outlet pipe to feed a multiple carburettors or return excess fuel to the fuel tank.

A Gemini has a continuous cycle fuel system where fuel that is not needed by the carburettor is returned to the tank and the fuel line pressure is kept reasonable constant. On a TX to TD with an electric fuel pump the Nikki is fitted with a bango with an inlet and an outlet connection for return fuel. On a TF-TG the with a mechanical fuel pump, the return fuel line is on the fuel pump and the carburettor banjo has a single inlet only.

Weber 32/36 carbs don’t accommodate banjos.


A 32/36 has two positions for an inlet to the needle and seat gallery and two outlet positions from the needle and seat gallery cast into the top cover casting. Depending on the application one or two of these outlets is drilled and has a pipe connection pressed in. Some of the early models – like the 5A only have an inlet (the first picture in this thread is a 5A) while later models have inlet and outlet. The inlets are angled down and the outlets are horizontal. The top cover has the outlet positions marked with an arrow which you can just make out on the photo below.

Image

Above – inlet on this 9E model is coming up from right and outlet horizontal left. Third pipe is the overflow

Image
Inlet and outlet both on the right of picture. No overflow pipe just the hole in the top cover.

For a TF-TG – if there is an outlet hole block it off (piece of fuel hose clamped on the outlet at one end and with a bolt clamped in other end – that sort of thing)

For a TX-TF preferably buy a carby with a fuel inlet and outlet or else use a T piece fitted close to the carby end and the return line slightly higher than the feed line.

Image

The other pipe in the top cover is the overflow in case the needle and seat fails – whatever you do don’t connect the anything to it. In some carbies it may even be missing.


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PostPosted: Thu May 28, 2009 5:07 pm 
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Cold Start Chokes

Carburettor cold start systems normally consists of a shaft and butterflies in the top cover that cause a richer mix to be drawn into the barrels when partly closed. Normally the butterfly position is linked to a fast-idle cam. The fast idle cam over rides the idle adjustment and opens the throttle a bit wider to let more air /fuel mixture flow. There is normally a mechanical or vacuum link that temporarily opens the choke butterflies if the throttle is opened up past a certain point.

When the engine is cold, fuel does not vaporise effectively. Activating the cold start choke allows more of a richer mixture to enter manifold to compensate until the engine warms up and the fuel begins to vaporise properly.

The Weber 32/36 come with three types cold start choke systems:

• Manual – DGV, DFV
• Water – DGAV
• Electric – DGEV

A lot of Gemini converters remove the choke mechanism and put up with the cold engine splutters and/or increase the idle speed to compensate. Main reason is to facilitate easy set up of the accelerator cable bracket using the mounting screws of the removed choke “pull-off” mechanism.

With a little more effort you can set up an electric choke and make driving a lot more pleasant on a cold morning.

The most common second hand 32/36 is the water choke DGAV version – a hopeless system to try to adapt to a Gemini. However the water choke “stove” interchanges with the electric “stove” that a Gemini is already wired to run because the Nikki uses the same electric “stove” system.

Image
32/36 DGAV converted to a 32/36 DGEV by replacing the water “stove” with the DGEV unit.

Image
32/36 DGAV converted to a 32/36 DGEV by replacing the water “stove” with the 34ADM stove unit with a DGAV bi metal spring. Note the bayonet power connection compared to the spade power connection on the 32/36 unit.


The correct “stove” can be hard to get but the 34ADM component is easier to find. If you use a 34 ADM stove the bi metal strip needs to be changed for the one out of the water choke.

To change the bimetal springs, gently spread the slot in the soft copper mount in the centre of the stove, insert the water choke spring and pinch the slot closed. (Check the photo and don’t put the spring in backwards – from the centre the spring should spiral clockwise.

Image

Note that the correct bimetal spring for a 32/36 has a looped end.

The unit that the stove is mounted to contains a vacuum “pull off” that opens the choke butterflies temporarily when the throttle opens. Between this unit and carby body is the linkage to the choke butterflies, fast idle screw and fast idle cam. The 32/36 has a separate fast idle adjustment screw to allow easy and foolproof adjustment of the idle speed when the choke is engaged.

Next episode - linkage set up


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PostPosted: Fri May 29, 2009 4:46 pm 
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Linkages

All sorts of interesting idea’s on this one already posted.

Lets start with the accelerator cable mounting:

This is a post for a quick and dirty “who needs a choke anyway” solution.

http://www.ozgemini.com/forums/tech/vie ... php?t=5419

A good post from Bugzzy. I can’t say I subscribe to using silicon as a gasket seal cos it’s soluable in petrol. Instead of using angle an alternative is to use a piece of 2 mm flat and spiral twist it 80 degrees at the cable end. I’d have the adaptor the other way round too – just being fussy I am sure this set up works great.


http://www.ozgemini.com/forums/tech/vie ... ight=weber

The above is a set up fort a DGV keeping the choke by archangle62.

This is a DGEV set up but not a good one.

Image

It works OK but the set up described below is simpler and won’t rub on the brake reservoir. My first effort.

For a DGEV set up I have tried a couple of ways but the set up below is probably my preferred and it is very easy. You need a piece of flat 2mm (ish) steel. Take the cover off the choke pull off mechanism and use it as a template to mark the 3 holes. Drill 3 holes in the steel the same size or half a mm larger than the holes in the cover.

Drill out the area between the holes and, using files or grinding tools, shape a hole in the steel plate such that the plate will fit over the cover and only touch the outer edge of the cover.

Image

Measurement x = level with filter mount, and y = somewhere between the two top screws of the “Pull off” cover.

Screw the plate on to the choke assembly. Don’t trim too much away from the outer edges yet. It is a good idea to replace the three screws with longer ones. The next step is to cut down a Nikki carby cable bracket -4 cm from the end. Line it up so that the cable (when fitted) points about 3 cm to the choke side of the throttle spindle and on and angle of 5 to 10 degrees. Tack weld it in that position temporarily.


Now the connection to the spindle.

But first lets talk about a mistake people make. The spindle is precision made such that when the original linkages and washers are fitted and the nut is tightened to the bottom of the thread – the tolerences are perfect. If you just cut down a Nikki cable connector / wheel and fit direct to the spindle it will be too loose or (with a washer) so tight that the secondary throttle linkage fouls the carby body. You can get around the latter and keeping the nut loose but prevented from moving by using the lock tab (r-r-r-r-r-rough!)

I suggest you mount a Nikki “wheel” on the original Weber “C” bracket that the original escort linkage connected to. If your set up needs the wheel close to the throttle body – cut down the “C” link and just use the flat section with the square hole to weld the wheel onto.

Image

You can clearly see the “C” link and wheel welded to it. Connecting the wheel in this manner gives you a bit more room to play with and is better for a DGEV set up.

Image

Cut the Nikki “wheel” down to suit, line it up with the cable bracket so that the end of the cable is a bit more than 90 degrees from the line of the cable. Tack weld in place.

Dry fit a cable making sure there is al least 2 cm pulled out at the pedal end to allow for pedal connection (which I did not do for the photo above ). Check the alignment and that the cable adjustment nuts sit around mid way on the thread. Re position the bracket of wheel if not happy. Once happy final weld and trim excess metal off as required.


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PostPosted: Tue Jun 02, 2009 5:59 pm 
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Tuning

There is a degree of frustration in the tuning of Webers for Geminis as noted in this post.

http://www.ozgemini.com/forums/tech/vie ... r&start=30

The links at the start of this thread are a good guide but a little assistance with a starting point would be good.

Lets bust a couple of myths first

“ a factory Weber for an 2 litre Escort motor should be close for G200” – nope!

Logic does not apply. Primary idles at 60 and primary main at 160 runs pretty sweet. The idle screw is in a fair bit with a 60 which is an indication that this size is a bit rich but 55 gives hesitation during the progression stage. With 60 primary idle and 160 main jet my G200 is crisp and smooth and the plug colour is perfect. I have the same combo on the secondary idle and main and I would not swear that it was 100% but it’s close. I might come down to a 55 on the secondary idle and /or 155 and see if it takes away that tiny bit of “boggy” feel when the secondary cuts in. The factory air jet sizes seem OK but you need to jump 20 in size with airs to get any real difference.

Kizza posted this for his G161

“here is a list of the jetting i have used on my current 32/36 weber.
the engine is a 1.6 litre bored 20thou, standard internals as far as i know.
extractors, inlet manifold ported out to gasket size.

primary idle jet 50
secondry idle jet 50
primary main jet 140
secondry main jet 132
primary air jet 190
secondry air jet 180

im not saying that its the right jetting but its definately driveable.”

Whats needed are more people to post up their set ups – particularly people who have had them professionally jetted. Taking the top cover off and having a look and unscrewing the idle holder and checking the number stamped on them is not going to stuff up anything - be brave.

The other myth is rough idle.

If the “O” ring on the idle jet holder is good, the internals are clean and the float level /needle and seat is OK – you can get a Weber to idle smoothly even if the jetting is totally wrong. At idle only the idle circuit is in play and the idle mixture screw compensates of oversize or undersize idle jets. It is only during the progression stage ( as the butterfly opens a bit more and sweeps past the progression holes) that the wrong idle jet size shows up.

If you can’t get a Weber to idle smoothly, its 95% likely it’s not a carburettor problem (sucking air, timing out, points, plugs, leads, condenser, cracked cap,). Don’t waste your time with further tuning of the carby till the source of the rough idle is sorted.

Similarly if the idle speed screw has to be wound in a long way to make the carby idle then the first progression hole may be contributing to the idle mixture to get an idle – as above something else is wrong.


Would really love to see some post of what jet combinations people use.


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PostPosted: Mon Apr 19, 2010 3:28 pm 
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I know this is an old post but it was good reading. I wonder if anyone experiences a dead spot in their weber and have managed to sort it out. It occurs in mine when you are backing off then accelerating again. It hesitates before powering on. Also have trouble getting it to idle. I can set it and it's great for a while then starts playing up.
Guess I should check the jet configuration.

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PostPosted: Tue Apr 20, 2010 1:40 pm 
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Vacuum leak (carby to maniflod or manifold to engine) for this sort of problem is the prime suspect. The manifold sucks a lung full of lean air on decelleration and rams it into the cylinders when you open the throttle. Another symptom of this problem is roughness when travelling about 55 -60 kph light throttle on a flat road.

If it is not vacuum then the next suspects are accellerator pump and idle jets.

Accellerator pump is easy to diagnose. The problem will be more pronounced on fast accelleration.

For idle jets (which also manage transition) they are either too small for the transition stage but more likley the idle jet carriers are loose or the O rings are perished.

Other wise it might just need a good clean and kit.


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PostPosted: Tue Apr 20, 2010 2:20 pm 
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Put a kit through it already. I am going to check the size of all the jets and tighten everything down. What you said about roughness while cruising is happening as well. I actually thought it was the points.
Thanks for your help Toby

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PostPosted: Tue Apr 20, 2010 8:14 pm 
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Well Well Well! Who would ever have thought that I would learn something on here? LOL
Just f*#cking around.
Decided it was time to take the top off my Weber and check all the jet sizes. Wow. I found a mix of jets that are not even mentioned in the specs . I found the following
130 air jet primary
175 air jet secondary
127 main prime
132 second
52primary idle
50 idle secondary
No wonder I was having issues
I dug out another weber in my stash and stripped it to find it was very similar. So I made a mix of jets that seems to work really well.
135 for both mains
175 for air ( I think) - i will check that as I had jets everywhere and am not really sure what I used
and 55 for idle - both
Damm thing has a new lease of life!
No dead spot Woohoo
:D

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PostPosted: Wed Apr 21, 2010 7:26 am 
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Has anyone got a couple of 140 main jets they don't need? I would like to see if they would make it even better

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PostPosted: Tue May 14, 2013 5:27 pm 
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OK guys

done 2 of these today... conversions that is, I think we should make a seperate Jetting thread however, i do not have the power to do so in this area.

Anyway,

For a g161z virgin motor TX early head and a very mild (slightly more lift than standard) the jetting was as follows to get it near on perfect, with electric ignition from turbogemini it will idle with aircon on ;)

Primary air jet 160
Secondary air jet 175
Primary fuel jet 140
Secondary fuel jet 160
Emulsion tube primary F5
Emulsion tube secondary F66
The idle air jets??? Primary 55
Secondary 50
Pump jet, not played with.

This runs a dream with standard timing and extra 4 degrees of mechanical advance (dizzy plate gap of 12mm)

My G180 with standard head, mild / stage 3 crow cam, turbogemini electronic ignition + timing set to 14 + mechanical with no vac advance, and total advance of the same as above has the following jets and feels good but i think it has a blocked secondary after the drive today. and maybe could go a smaller air jet in the secondary or bigger fuel jet.

Primary air jet 175
Secondary air jet 175
Primary fuel jet 150
Secondary fuel jet 180
Primary emulsion tube F5
Secondary Emulsion tube F66
Idle jet primary 55
idle jet secondary 55

This ran good but a bit sluggish in secondary's im going to assume its the factory pea shooter exhaust so have decided to retune after the exhaust gets fitted.


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PostPosted: Wed May 15, 2013 1:01 pm 
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Secondary mains being higher that primary is an uncommon arrangement. Try going leaner on the secondaries as an over rich mix could be bogging it down.

Not saying your setting is wrong but if you are loosing the kick that the secondary should provide it is worth playing with jetting.


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PostPosted: Wed May 15, 2013 2:26 pm 
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in a 32 36 it should still be a larger jet as the venturi is larger. well thats my perception.

anyway. Yes its less a stuttering more like a heartbeat miss. but it comes good. i think its just blocked.


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PostPosted: Wed May 29, 2013 10:32 am 
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I have since revised both tunes.

for my g180 as above im now running

PIAJ 60
SIAJ 55
PAJ 160
SAJ 170
PFJ 150
SFJ 180

this appears to be perfect.


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