Weber 40 IDF kit for Variant 411

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Braamn
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Re: Weber 40 IDF kit for Variant 411

Post by Braamn »

Just spoke to him , he said all the right things , dropping car off on wednesday


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73type2
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Re: Weber 40 IDF kit for Variant 411

Post by 73type2 »

For me turn around time was less than two weeks. The guy took one look at my Solex's and knew exactly what it was and what to do. With kits not locally available he knew which local kits to combine to get all the right bits. Throttle shafts were reamed and re-bushed, etc......, and I'm very satisfied. All this for R3700 for both carbs. I only took the carbs in, though, and installed it myself, as well as synced them, so your cost might be a bit higher...
Braamn
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Re: Weber 40 IDF kit for Variant 411

Post by Braamn »

73type2 wrote:For me turn around time was less than two weeks. The guy took one look at my Solex's and knew exactly what it was and what to do. With kits not locally available he knew which local kits to combine to get all the right bits. Throttle shafts were reamed and re-bushed, etc......, and I'm very satisfied. All this for R3700 for both carbs. I only took the carbs in, though, and installed it myself, as well as synced them, so your cost might be a bit higher...
Thanks for the lead


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Dawie
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Re: Weber 40 IDF kit for Variant 411

Post by Dawie »

Remember that these carbs have tiny floats and cannot handle more fuel pressure than the standard mechanical pump. They are incompatible with the pressure of most electric fuel pumps.
They also use smaller needle & seats of 1.2mm. Some carb kits have the wrong 1.5mm n&s from a beetle. Best to re-use the original ones. I have lapped them with brasso.

Float level is critical. Book says 12-14mm, but i found that 14mm is the absolute limit, 13 or 12 not ideal.

Otherwise check accelerator pump nozzles to confirm they are not blocked. Also check idle/progression jets/cutoff solenoids. (These obviously need 12V applied to open while cleaning when using air pressure).
My humble experience with these carbs are that even with moderate wear, they still function good.
Last edited by Dawie on Mon Oct 02, 2017 2:06 pm, edited 1 time in total.
Staying Aircooled is so much nicer.
Do'nt assume anything- (While doing fault-finding).
Braamn
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Re: Weber 40 IDF kit for Variant 411

Post by Braamn »

Thanks a mil Dawie I’ll take him through your post when I drop off on Wednesday


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Tony Z
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Re: Weber 40 IDF kit for Variant 411

Post by Tony Z »

I weighed the floats and they came it at perfect spec.
The pump jets are clear but the one dribbles at best and the other is better but still not good.
I cant remember the needle jet size, but I am sure it was to spec.

The linkage was loose and so were the throttle levers. Also adjusted way out of sync.
Vacuum piston on the one carb was missing and so was the plug. This opened up a port from the manifold right through to atmosphere - I plugged this with a brass wire and some sikaflex. The other carb had the grub screw which holds the venturi in place missing, so this was a nice 6mm hole open to atmosphere.
The jets are stock size and I did measure them. Some might have been a little over size, but only by 5 (0.05mm).
Chokes were seized in place and not open all the way. I didnt bother trying to fix these but instead made sure they were open properly.
Throttle cable was only able to open the carbs about half way. I adjusted this and noticed that (before I started trying to look at the carbs) that the engine would bog down badly above half throttle - so much so that with the engine in the driveway in neutral, I couldnt get it to rev over 3000rpm. This is when I checked the timing and found it advanced about 20deg too far - probably in an attempt to correct the flat spot.
Resetting everything the car idled nicely but wouldnt rev. This is when I took the carbs apart, cleaned them, measured jets and did what I could for them with my limited knowledge on these carbs.
I put them all back together and tweaked the linkage as well as i could to remove almost all the play/slop. I then sync'd the carbs at idle and at 2000rpm. I also adjusted the timing to be to spec.
O yes, on the engine, I found the valve gaps all set to 0.5mm, so I adjusted these to 0.15mm as per spec.
New plugs, dizzy cap, new rotor. Electronic ignition installed - external box using points as a trigger signal.
Fuel pump was shot - leaking with torn diaphragms, so after not being able to source a replacement, I installed a fuel pump, internally regulated to 3psi. I use the same pump on my cars with webers whose floats also lift above 3psi.
After all this, the engine revved up nicely to set the timing and the car is much more drivable than before. But it still bogs down above half throttle - for no reason that I can make out. Feathering the throttle, it has little to no issue getting to 100km/h.

Also I noticed that at higher rpm, fuel does come out of the pump jets without moving the throttle. I know this is normal on some carbs, but not sure about these. I actually forgot about this until now...

Either way, the car runs/ran a lot better after I finished with it than before. But it isnt perfect.
In my opinion, that engine is rock solid and nothing to worry about. I think the issues are currently with the butchered carbs. Hopefully the guys looking at it now can sort it out.
Braamn
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Re: Weber 40 IDF kit for Variant 411

Post by Braamn »

Thanks for the info Tony !!


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Braamn
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Re: Weber 40 IDF kit for Variant 411

Post by Braamn »

Morning guys just some feedback on the Carbs , had the Solex carbs rebuilt at Carburetor Repairs in Paardeneiland , and although it was not cheap , I’m really stoked with the result , she is a different car all together !! Thank you all of you for the input !!


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