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 Weber carb bits.....Choke Sizes
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transit80
V4 Mad

United Kingdom
775 Posts

Posted - 26 May 2012 :  21:33:35 Show Profile Reply with Quote
Does anyone have an old Weber 28/36????, I need a different choke as the one in my primary choke is too small, it is a 26mm(?) and I need a 29mm(?). Had some help of another forum member today and the general idea was that because the engine has had a new 4 stud manifold put on it the choke in the primary choke is too small because it will not tick over unless the choke is about half open and its revving at about 2500-3000 revs, as soon as you put the choke in it cuts out, also it will not start unless the choke is out even when warm. This is probably not the only problem,if you have any ideas please feel free to let me know,also if anyone has a weber 28/36 on their 96 and it runs properly please let me know what the choke sizes are.

But it starts and runs in a fashion.

Chris

Edited by - transit80 on 27 May 2012 07:49:11

TTruckie
V4 Fanatic

United Kingdom
277 Posts

Posted - 27 May 2012 :  09:13:08 Show Profile Reply with Quote
Hi Transit,

not sure if this is masking another fault also? I have had a bunch of different carbs and choke sizes but never had that extreme of idle issue. I suggest your check the carb set up and also any air leaks etc.

Good luck

TT
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Clive H
V4 Fanatic

United Kingdom
394 Posts

Posted - 27 May 2012 :  09:19:02 Show Profile Reply with Quote
Chris,

My primary choke is 26mm and secondary choke 27mm, main jets 140 and 155. Starts and runs well on this set up.
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pchristy
V4 Guru

United Kingdom
1737 Posts

Posted - 27 May 2012 :  09:26:54 Show Profile Reply with Quote
The choke / jets should be the same as a Cortina 1500 GT, which according to this site:

http://freespace.virgin.net/tommy.sandham/weber.htm

means you have the right choke. Mine is exactly as that site says, and runs fine.

It sounds to me like you have a blockage somewhere. Another possibility is that the crankcase breather valve is stuck open, allowing a massive air leak into the manifold.

So: 1) Check and clean the crankcase breather valve.

2) Get an overhaul kit and completely strip and clean the carb. It isn't difficult, but setting the float height is fiddly!

I bought a small ultrasonic cleaner from Maplins that has been worth its weight in gold for cleaning small parts! I cant quite get a whole carb in it, but you can get it in a bit at a time. I did the 34ich on my 95 like that!

Also Webers are prone to air leaks on the primary spindle. How to fix it depends on whether you have a brass or steel spindle - ie which bit has worn. This won't stop it running, but will give a poor and erratic tickover. It can be diagnosed by dropping some thick oil on both ends of the shaft while the engine is running. If there is a leak, the tickover will smoothen out, while the oil will gets sucked in! However, your case sounds much worse than this!

You have the right chokes, so start looking for blockages / air-leaks!



--
Pete
"Duct tape is like the Force: It has a light side and a dark side, and it binds the Universe together!"
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Woody
V4 Guru

United Kingdom
2377 Posts

Posted - 27 May 2012 :  14:45:39 Show Profile Reply with Quote
Some info to digest. My 28/36 used to run OK, always needed a bit of choke, and now has a worn primary spindle. I've sent the file to you Chris. Still got same email address?


Weber 28/36DCD Jettings

1498 1498 1730 1730

1st 2nd 1st 2nd

Main Jet 120 130 135 175
Idle Jet 50 40 50 50
Emulsion Tubes F30 F30 F30 F30
Air Corrector 230 180 230 180
Accelerator Pump Valve
Accelerator Pum Jet 55FW 70FW
Intake/Discharge Valve 35 35
Needle Valve 175 175
Chokes 23 24 26 27
Auxiliary Venturi 4.5 4.5 4.5 4.5
Starting Air Jet 150 150
Starting Fuel Jet 100F1 100F1

SAH Stage III Tune John Passini
Ford 1700 V4
1498 1498
1st 2nd 1st 2nd

Main Jet 140 170 145 145
Idle Jet 50 40 50 50
Emulsion Tubes F30 F30 F23 F30
Air Corrector 230 180 215 160
Accelerator Pump Valve
Accelerator Pum Jet 35 70
Intake/Discharge Valve
Needle Valve
Chokes 26 27 27 28
Auxiliary Venturi 4.5 4.5
Starting Air Jet
Starting Fuel Jet


Edited by - Woody on 27 May 2012 14:52:54
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transit80
V4 Mad

United Kingdom
775 Posts

Posted - 27 May 2012 :  17:26:48 Show Profile Reply with Quote
Have replied to your email, hope you can understand it.

Chri
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transit80
V4 Mad

United Kingdom
775 Posts

Posted - 27 May 2012 :  17:33:17 Show Profile Reply with Quote
quote:
Originally posted by pchristy
The choke / jets should be the same as a Cortina 1500 GT, which according to this site:

http://freespace.virgin.net/tommy.sandham/weber.htm

means you have the right choke. Mine is exactly as that site says, and runs fine.

It sounds to me like you have a blockage somewhere. Another possibility is that the crankcase breather valve is stuck open, allowing a massive air leak into the manifold.

So: 1) Check and clean the crankcase breather valve. DONE

2) Get an overhaul kit and completely strip and clean the carb. It isn't difficult, but setting the float height is fiddly!.WILL DO NEXT WEEK

I bought a small ultrasonic cleaner from Maplins that has been worth its weight in gold for cleaning small parts! I cant quite get a whole carb in it, but you can get it in a bit at a time. I did the 34ich on my 95 like that!

Also Webers are prone to air leaks on the primary spindle. How to fix it depends on whether you have a brass or steel spindle - ie which bit has worn. This won't stop it running, but will give a poor and erratic tickover. It can be diagnosed by dropping some thick oil on both ends of the shaft while the engine is running. If there is a leak, the tickover will smoothen out, while the oil will gets sucked in! However, your case sounds much worse than this! HAVE ALREADY REPLACED THE SPINDLE

You have the right chokes, so start looking for blockages / air-leaks!



--
Pete
"Duct tape is like the Force: It has a light side and a dark side, and it binds the Universe together!"

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pchristy
V4 Guru

United Kingdom
1737 Posts

Posted - 27 May 2012 :  19:44:07 Show Profile Reply with Quote
In that case my money is on a blocked idle jet! If that is the case, the dirt must have come from somewhere, so even if you clear the jet, its worth giving the carb a good internal clean so it doesn't block again.

And check the filter!



--
Pete
"Duct tape is like the Force: It has a light side and a dark side, and it binds the Universe together!"
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transit80
V4 Mad

United Kingdom
775 Posts

Posted - 27 May 2012 :  20:17:24 Show Profile Reply with Quote
Cheers Pete,Clive,Woody and TT, new filter on order, have found some of the jets for the carb in me spares stash. Im going on holiday next week so the car will have to be sorned as the MOT and insurance run out while we are away.
Are there any places where I can get me carb ultrasonically(?) cleaned??, and how much??.
Another idea!!!, at the moment I am using me machined out SAH adapter, now I know it is flat on both sides and all the gaskets are new but it is 3/4 of an inch thick, would it be a good idea to use me Solex adaptor plate which is thinner??.

Chris
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pchristy
V4 Guru

United Kingdom
1737 Posts

Posted - 27 May 2012 :  21:22:03 Show Profile Reply with Quote
My original car, back in the early 70's had an SAH adaptor and it never gave me any problems, but I was using a pancake filter. Have you got a clearance problem? If not, the SAH is as good as anything else.....

You want the transition from a big hole to a small one to be as smooth as possible, so I'm guessing the SAH one would be better. I'm not familiar with the Solex one.

A blocked jet isn't a major issue. If you can't get an ultrasonic cleaner, give it a good swill in cellulose thinners. In fact, you could clean the whole carb like that, but make sure you remove any rubber o-rings first!



--
Pete
"Duct tape is like the Force: It has a light side and a dark side, and it binds the Universe together!"

Edited by - pchristy on 27 May 2012 21:26:05
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rsimps
V4 Guru

United Kingdom
1616 Posts

Posted - 31 May 2012 :  07:53:05 Show Profile Reply with Quote
26 or 27 primaries in all mine for a std engine and two were rolling road set up.
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rsimps
V4 Guru

United Kingdom
1616 Posts

Posted - 31 May 2012 :  07:54:18 Show Profile Reply with Quote
Your idle jet is probably too small or blocked, so going to a larger choke will make the problem even worse.
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melle
V4 Guru

United Kingdom
2270 Posts

Posted - 16 Jul 2016 :  23:23:46 Show Profile Visit melle's Homepage Reply with Quote
Digging up an old thread. I'm in the process of refurbishing 3 DCDs with different venturi sizes (23-24, 24-25 and 26-27) to see what they do on my 96's soon to be freshly rebuilt engine.

Woody, you posted below settings for a 1.5 earlier in this thread. Were this the settings you used on your car or what is the source? I'd say 23-24 venturis are on the small side, on the other hand the smaller the diameter the higher the speed of the airflow?

Are you sure the starting fuel jet is 100F1? In the six or seven DCDs I've taken apart I've only come across 150F1 and 165F1s and my 23/24 carb had a 150F1 starting fuel jet fitted. I don't think you can get these jets anywhere.


1st 2nd
Main Jet 120 130
Idle Jet 50 40
Emulsion Tubes F30 F30
Air Corrector 230 180
Accelerator Pump Valve
Accelerator Pum Jet 55FW
Intake/Discharge Valve 35
Needle Valve 175
Chokes 23 24
Auxiliary Venturi 4.5 4.5
Starting Air Jet 150
Starting Fuel Jet 100F1

Other than that I need to find a 230 air corrector jet and a 120 main jet, these should still be available (the main is identical to the ones fitted to the DGV).

www.saabv4.com
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Woody
V4 Guru

United Kingdom
2377 Posts

Posted - 19 Jul 2016 :  06:42:01 Show Profile Reply with Quote
The first two lists were carbs I used. The 1500 carb came via a friend and had been set up for a standard v4. The second was on A 1730 engine when I bought the car TDN110T. It worked well with those settings. The third is a list in a book by John Passini used a reference point for the first two.
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melle
V4 Guru

United Kingdom
2270 Posts

Posted - 19 Jul 2016 :  10:06:08 Show Profile Visit melle's Homepage Reply with Quote
Thanks Woody, that's helpful. I'll see if I can get a 100F1 starting fuel jet somewhere and otherwise I'll try a 150F1. I also have the Passini book, but I can't find your table there. Maybe it was in the first two part edition and ditched for the later version that combines both. I have a Weber DCD factory manual coming in tomorrow, but I don't expect that to list jet settings. It does show all special tools and overhaul procedures though, which I think is really cool. I've never used a DCD on a car so far, but I really like the quirky design and I'm looking forward to trying them out.

www.saabv4.com

Edited by - melle on 19 Jul 2016 10:06:39
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