fulvia carburators problems

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ph21
Posts: 2
Joined: 07 Jan 2019, 20:24

fulvia carburators problems

Post by ph21 » 07 Jan 2019, 20:52

Hi,
I'm waking up a 1300s fulvia s2 from 1972 i presume, bought from second hand .
seems to be a very good unit but the carburators makes me now nightmares.(solex c35 phh 19 rear and 16front)
I completely dismantled them and cleaned all parts, the old petrol had glued inside.
I cleaned the main bodies in an ultrasonic machine, also the various jets.
The engine waked up, and I made the settings, idle petrol proportion and synchronisation;
The engine turns pretty well when in the garage, but when I drive the car, it don't want to overpass 3000 rpm.
Seems to be poor at 3000 and over. It's possible to overpass when activating the cold choke, or when pumping on the pedal to feed petrol throug the acceleration pump.
Due to this problem, I dismantled again for checking 8 or 10 times, but no real changes.
Thinking to be a faulty air intake , i dismantled today all the pipes but seem to be ok ; I also closed the vacuum hose for the brake servo; the problem still remain.
I discover also today some cracks along the central choke tubes attached to the cover, and welded them ; but I think those tubes can only act when the choke is activated .I didnot tested the car after... I will see tomorow but without any hope.
Last precision, I progressively rose up the petrol level in the chambers; Its now about 20mm as precised in the tecnical datas.
some ideas?

LanciaFin
Posts: 3
Joined: 04 Dec 2011, 16:40

Re: fulvia carburators problems

Post by LanciaFin » 08 Jan 2019, 21:48

Hi,

This can be a problem with ignition as well. I'd check that side next. Maybe with another coil first?

ph21
Posts: 2
Joined: 07 Jan 2019, 20:24

Re: fulvia carburators problems

Post by ph21 » 09 Jan 2019, 00:04

Hi, LanciaFin,
may be, may be you are right...
But a good new today, this post will not be very large, because after some hours of work , the problem is now solved.
First test by this morning , no much progress.
I dismantled all the carbs again and decided this time to clean with a lot of care the only circuit I did not dismantled before the ultrasonic bath;
This circuit is called by a strange term in french "circuit de désiphonnage ", may be " siphon off circuit" or "drain circuit in english? This circuit is a pass beetween the main petrol vat and the pump vat . Under two plugs there is a weight pushing on a ball . And various air circuits inside and around.
after reassembling the carbs and fitted onto the car, I also took care to verificate the ignition . I found the excentric system into the ignitor with some play on the weights and also bad moves due to old grease, dust and surface rust. So may be the excentric advance was not optimal.I renewed those parts.
so the problem was due to a bad function of the siphon off circuit ,or only bad ignition , difficult to say ; but for those waking up, old solexes 35 with decades of glued old petrol inside, dont hesitate to take care to this circuit...
Now I'm happy finishing to solve a problem wich occupied me the three last weeks...
Hope this wiil help ,and thanks to LanciaFin. :mrgreen:

Huib
Site Admin
Posts: 216
Joined: 17 Dec 2008, 10:12

Re: fulvia carburators problems

Post by Huib » 09 Jan 2019, 10:54

Bonjour,

The steel ball with the weight on top is a valve between the acceleration pump and the acceleration jet. The acceleration pump is the principle of a bellows. The valve at the input is a steel ball hidden in the seperation between float chamber and pump (thus the bottom of the float chamber). You can't see it. To check if the ball moves freely I shake that part nex to my ear and listen.

At the output of the bellows are the two valves as you describe. Each barrel of the carb has its acceleration jet and each acceleration jet has its valve.

You may want to check that the acceleration jets work. Look into the barrel and flip the throttle. You should see a squirt from the jet at the top of the barrel near the butterfly valve.
Huib



Lancia specialist. Netherlands - Niederlande
www.casa-fulvia.nl
www.casalancia.nl

LanciaFin
Posts: 3
Joined: 04 Dec 2011, 16:40

Re: fulvia carburators problems

Post by LanciaFin » 09 Jan 2019, 22:17

Ok, I thought the carburettor had been opened everywhere already, so the ignition seemed quite obvious culprit. But anyway, it runs now fine, so nothing else matters. :)

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