Could it be the problem? Yes! There are thousands of things that could be the problem.

So instead of trying every idea that comes along, it is generally better to have a plan.

Please try the accelerator pump test we talked about before. What are your test results? Good to see that your mechanic pronounced the Dwell as being correct.

I made that test to the pump and is good. The car runs good until a certain temparature and then goes down unless i`m not driving, if i stop for some reason th car dies, the car must be jinx...:( so much time waiting for driving it and now this....

Take a better look at the carb as a whole. When your car is cold it is choked allowing vacuum leaks. After it has warmed and the choke is opened and idled down it can not tolerate bad vacuum leaks, thus it would stall at idle. I would be suspect of your vacuum hoses and or a faulty carb unit. Try spraying carb cleaner at your carb and vacuum hoses, if it causes your idle rpm to increase you found your problem. Do this when the engine is cold, to aid in it staying running as you perforn the test.

Thanks Eric. I will change the carburetor and put one from an A15. If it doesn`t work i will start disconnecting all emmission control devices in the carburetor! Do you think that the air-pump is good or bad in terms of performance?
Thanks once again

What does the carb cleaner does exactly? does it stop the leaks?

No, not permenantly, it displaces the leak with fluid rather than air, after the fluid is sucked in your air leak returns, in a franction of a second. But in that fraction of a second you can determine where your vacuum leaks are. If you use the carb off of a manual tranny, the jettings may be different and there are other ancillary parts that are different on the auto carb.

Or alternately, the carb float level could be too high.

When cold, the extra rich mixture is OK, as it is the same as when some choke is applied, but when warmed up the volume of fuel vapour is excessive & the engine chokes from overfueling.
Looking at the little window in the front of the fuel bowl will very quickly verify if this is a problem.
The description of the symptoms seems to fit.

If this is the problem then it is easy enough to fix by following the instructions in the workshop manual.

It never fails to amaze me whenever a problem occurs, so many people start clutching at straws rather than get back to basics.
A full & proper tune up exactly as per the book will rectify a great many faults & if not, will establish those things that are NOT causing the problem.

If we are going to maintain our cars at home then the absolute minimum requirement would be a workshop manual, a reasonable tool kit, a timing light, some spares [like fuel filter, plugs, points, rubber fuel & vacuum hose etc] If points are still being used, then a dwell angle meter is always a good idea. [Did I say 'WORKSHOP MANUAL? Very important tool that one.]
Another really good diagnostic & tune up tool is a large diameter vacuum gauge if you can source one.

Without these things it might be better to take it to a competent mechanic. [Make sure he has a workshop manual]

I will do all those checkings! The problem is that i put the car in the mechanic and the problem is still there. Maybe they dont understand anything about datsuns or other old cars.
One thing i noticed is that the level in the carburetor is cover in dirt and so the mechanic didn`t tune the engine by cheching the float level, only "by hear".
Thanks again to all

It is very common with new cars, for the mechanic to do some work, but not fix the problem. It seems you have one of those mechanics.

Quote:This is why I said "a competent mechanic"

Any tradesman who thinks that he can diagnose & rectify/tune engines without the correct tools & without the correct technical information is delusional.
This applied fifty years ago as much as it does today.

Trying to fix your problem 'by hear' is laughable & this fellow may not be worth feeding. [sometimes known as an 'oxygen thief']