Tech Forum : Solex 4A1 carb questions

Tricord	Posted Wednesday, Jul 9th 12:05am [Edit] [Quote] [IMS] [View car]
Administrator Post nr. 127 Belgium, Europe 323i Baur	Okay, I decided to leave the 323i be for now and to tackle the beast that is the 320/6 carb. I have two 4A1's, which I dismantled and selected the best pieces from to assemble a new one, using the rebuild kit with gaskets from Walloth & Nesch. I think I did the rebuild allright, at any rate the car runs now (and for that matter, better than ever when giving full throttle). Some notes though: The upper butterfly flaps of the big barrels do not come easily back into closing position. The spring is ok so I will probably have to try to oil the bearings. When the car is running, opening throttle using the kickdown (i.e. opening the big barrels) stalls the engine when cold (didn't used to do that). Idle seems erratic, depending on the rpm you were doing when you went to neutral. Sometimes it's just 1500, sometimes as high as 3000 (here again, I might blame some bearing or spring that is stuck). Cold start is a dream, however I can forget about starting hot. If I stall or shut down the engine, I have to wait like 10 minutes before it actually fires anything when it cranks. Other than that, I'm very glad to have done this job. I've learned a great deal about the carb, and top end performance is at least 15% better, and 50% better between 3000 and 4000rpm (which I love now ) because I used to drown the engine between those rpm values. Needless to say the hot start issue is the most problematic. Any suggestions welcome. When I get it running perfectly right I will add an article about the rebuild to the projects page.

Greg323i	Posted Wednesday, Jul 9th 5:49am [Edit] [Quote] [IMS] [View car]
Member Post nr. 10 Melbourne, Australia 1982 Hennaröt 323i	I would say that the butterflies are probably slightly off-center and probably just need to be aligned. Wide-open throttle problem is probably a bad or misadjusted accelerator pump. Hot start problem is probably a misadjusted float level. I can't be specific to the Solex carb because I've not seen one, just practical experience with carbs in general.

Tricord	Posted Wednesday, Jul 9th 1:07pm [Edit] [Quote] [IMS] [View car]
Administrator Post nr. 129 Belgium, Europe 323i Baur	Thanks! I will try adjusting the automatic choke housing, which determines the mixture richness. I admit I might have tensioned the bimetallic spring too much, so I'll see what it does when I tone it down a bit. If that doesn't help, I'll have to open the carb again and check the floaters and needles.

Tricord	Posted Thursday, Jul 10th 1:19pm [Edit] [Quote] [IMS] [View car]
Administrator Post nr. 131 Belgium, Europe 323i Baur	Are there any other indications of running lean, apart from higher engine temperatures?

Yety	Posted Thursday, Jul 10th 1:33pm [Edit] [Quote] [IMS] [View car]
Member Post nr. 33 Europe, Romania 320i/6	"Spooky" or not, my Solex looks exactly like yours, but the 3 other A4 Solex-es I recevied have only one electric valve that cuts off the fuel entering the float chamber... besides other small differences. Maybe when I'll had the time, I'll try to obtain from these 3 a good one and if it works, I'll post it as available for anyone who needs it and can afford to pay for shipping only Now about the subject of this thread : As I noticed, the 2 big barrells work only at over 3500 rpm if the gas pedal is pressed enough, as the little vacuum unit from the engine side of the carburettor keeps them closed until this level of rpm is reached. The "flapses" closing these 2 big barrells do not have any bearings, as I discovered when I had to dismantle them, because they seemed to be stuck, so I polished a little the rotating axle (made from some sort of bronze, I guess) and everything worked fine since then. I also had to change that little vacuum unit that keeps the big barrells closed under 3500 rpm. About the accelerator pump : I adjusted it's travel in order to pump gas at the slightest pression on the gas pedal, but before the pedal is fully pressed ("to the metal"), the pump reaches the end of its travel. Using a diaphragm with a longer travel is out of the question, so this adjustment is "a matter of taste" . IMHO, when the pump is at the end of its travel, the 2 big barrells are usually working, but that means not to push the pedal down too quickly at low rpm... It's just a carburettor, not an electronically controlled injection so I'm trying to adapt my driving style to that... I hope this will help and I'm sorry for the lack of technical terms in my vocabulary, but I'll work on that too