320/4 with starting / Solex problems

[E21-driver]

Guys,

after coming back from my holiday , I started to work again on my engine problem. Please have a look on this enrichment valve of the Solex carb.
The service kit was new. But there is a hole in the new diaphragm ! I have never seen it when I put it in. But after detailed search in found this picture in front of me:



This means it is defect ? Could be the reason why it was running too rich permanently ?
And what about the small washer, should it be under the nut or under the diaphragm ?
I am not so sure if this is assembled correctly. Maybe also Peter can have a look on it ? Thanks.
M.

[E21-driver]

Hi guys,

New results in this issue. I had a Weber 32/36 DGAV on my shelf, so I decided to put in a rebuild kit and to install it into the engine. Just to see if the engine really is ok. After twenty minutes I could start it, and it was running and idling like never before. I used additionally a carb pressure regulator from Sytec and the system works now.

I identify these root causes of my long lasting problem.
The Solex housing is warped at different places, I would say nearly in all sealing areas. So I trimmed them all on a glass plate, and the problem was much clearer visible. You couldn't see with with the eyes, but with a bright LED lamp.
Second cause was the stock 320 fuel pump. It was delivering too much fuel without using the return line and the return valve. I don't have a return line, because the car is originally a 315. But I could solve it with the regulator. I am sure that the ETK has not the right information concerning the pump.

Third reason - I am not 100% sure - may be the enrichment diaphragm. See the picture of my previous post. I put it from Solex one to Solex two, so I obviously installed a problem from one to the next. All pictures I saw for the BMW diaphragm were wihout this hole. And also an old one which I took out of the Solex.

So my patience was really exhausted, but at the end I am happy to see that iginiton and engine are working now, and I have learned a lot about Solex issues. I will use the Weber for a while....but the Solex story will not end here. I will bring it to a running condition.

In the next days, I will tune ignition, valve clearance and CO and then I will see how good the Weber is working.

Maybe somebody has an info about this mysterious diaphragm ?
M.

[Jeroen]

At least you made huge progress for now, good news!

[E21-driver]

I am going to have fun for the next weeks.
I want to thank you and the other guys for the help, I will report again.
M.

[Peter V.]

Great news that the weber setup is working fine. At least you can drive it now. As for the diaphragm.....

That hole is not OK, I have a picture of the normal setup and there it is not. The washer and nut are OK that way

[E21-driver]

Thank you Peter for the picture, I have checked again the Solex manual. If there is a hole in the diaphragm, the enrichment valve can not be closed by a permanent vacuum. This means, it stays open also in idle mode and will permanently enrich the mixture.
I am also sure that BMW version is without hole, but I have seen this part some times with hole. There seem to be cars also with this hole.
M.

[E21-driver]

Hi guys,

at the weekend, I adjusted also ingition timing, and the car runs very smooth now. Very happy with the result. Does somebody know, how the electric choke works ? Same as in Solex ?

Step 1: when engine is cold (under a certain sensor temp.), the sensor is open, 12V are not available at the electric choke, the choke flap is closed.
Step 2: when engine is warm (over a certain sensor temp.), the sensor is closed, 12V are availabe at the electric choke, the choke flap opens.
Am I right ?

[Peter V.]

Indeed it looks like the system is the same as the solex.