CS runs with issues but can't find the problem

Niels Schoon

Niels Schoon

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Hi All,

I would like to get some advice.

Situation: car has run perfectly for many km's, but suddenly start to stutter.
Have cleaned the carbs, vacuum is all okay. Have replaced ignition with 123igntion. Also the alternator has been revised.
Car runs for 5 km better (still a bit slow on acceleration) but after a while stuttering is back. Even to the extent I hear sometimes the firing in the exhaust.

Question: as I have done all cleaning and have seen the jets are clean and the acceleration tubes also etc, could it be related to an electric issue ? Mass somewhere playing up or other ? Any help appreciatted.

Thanks, Niels
 
what kind of carbs, is the firing in the exhaust a deep booming sound or a high pitched pop say on a downshift or over run?

Have you checked your timing?
 
Have you replaced the fuel tank pickup screen? It could be filled with rust and crud and starving the carbs of fuel. I'd check that and make sure you replace the fuel filters as well.
 
Hi,
Zenith carbs.
Yes cleaned and replaced all with fuel related.
Timing is double checked but is correct
Update:
- found one loose elec. connection on the first carb (bottom connection) and that 'solves' the and the popping in the exhaust.

What remains is following behaviour: little bit slow reaction on first acceleration and a bit stuttering, but ones accelerating it does well. So for instance in gear 3 with 30-40 km/h and then try to accelerate will give stutters and slow reaction, however in higher sped that is gone ?

Suggestions appreciated.
 
Confirm that your accelerator pumps are working by looking down the primary venturi and opening the throttle. you should see a healthy spray of gas on each push

Niels Schoon said:
Hi,
Zenith carbs.
Yes cleaned and replaced all with fuel related.
Timing is double checked but is correct
Update:
- found one loose elec. connection on the first carb (bottom connection) and that 'solves' the and the popping in the exhaust.

What remains is following behaviour: little bit slow reaction on first acceleration and a bit stuttering, but ones accelerating it does well. So for instance in gear 3 with 30-40 km/h and then try to accelerate will give stutters and slow reaction, however in higher sped that is gone ?

Suggestions appreciated.
Click to expand...
 
Last edited:
Thanks,

The acceleration pumps are working fine as both give a Spray of gas when doing that.

The example of 3th gear was just an example to illustrate car behaviour, but is also applicable for second gear and even first gear to get away. In that example you feel the car hesitate to get going , but when more speed doing fine.
 
If you mean by manually closing the air valve of each of the carbs a few times while the engine is in high rpm ? Yes that is done.
If there are more or other ways please let me know how to
 
no i mean by putting the synchronmeter on them at idle and at 3k rpm to ensure the linkages are adjusted correctly and each carb draws the same amount of air.
 
dear niels, sometimes is dificult to know what you are doing and what others are doing, when you refer to timing or to synchronizing

you seem to have a transition problem, something that happens, irrelevant to gears, but speaking in rpms, from 1200 to 1800

who knows in which condition your carbs are, even when they are profesionally overhauled, that is subjective too

i recall a lot of time ago i had a bad accelaration performance, suspicious where carbs, but fault and culprit where points dwell angle

hope this videos shed some light, as to what steve was recomending you to do



if you do this and still have problems you probably would need to change or rebuild something,...
 
Niels Schoon said:
If you mean by manually closing the air valve of each of the carbs a few times while the engine is in high rpm ? Yes that is done.
If there are more or other ways please let me know how to
Click to expand...

what is the purpose of this ?
"]If you mean by manually closing the air valve of each of the carbs a few times while the engine is in high rpm

a few times, eh ?
 
Have you added fuel or are all these problems taking place with the same gasoline?
 
Simple question: How many Km on the motor? Are those original Kms? Or how many since engine rebuild?
 
Niels Schoon said:
Hi All,

I would like to get some advice.

Situation: car has run perfectly for many km's, but suddenly start to stutter.
Have cleaned the carbs, vacuum is all okay. Have replaced ignition with 123igntion. Also the alternator has been revised.
Car runs for 5 km better (still a bit slow on acceleration) but after a while stuttering is back. Even to the extent I hear sometimes the firing in the exhaust.

Question: as I have done all cleaning and have seen the jets are clean and the acceleration tubes also etc, could it be related to an electric issue ? Mass somewhere playing up or other ? Any help appreciatted.

Thanks, Niels
Click to expand...

Niels Schoon said:
Hi All,

I would like to get some advice.

Situation: car has run perfectly for many km's, but suddenly start to stutter.
Have cleaned the carbs, vacuum is all okay. Have replaced ignition with 123igntion. Also the alternator has been revised.
Car runs for 5 km better (still a bit slow on acceleration) but after a while stuttering is back. Even to the extent I hear sometimes the firing in the exhaust.

Question: as I have done all cleaning and have seen the jets are clean and the acceleration tubes also etc, could it be related to an electric issue ? Mass somewhere playing up or other ? Any help appreciatted.

Thanks, Niels
Click to expand...

Hi;
I guess it's kind of silly but I once had a problem with my first BMW and it turned out to be a loose ground cable to the enginej.
Thanks
Koopman
 
Last edited:
Hello Niels, Did you switch over to the 123 Ignition and then start having your problem?
About a year ago I installed a Petronix ignition in a VW bug with a Bosch Blue coil. The car would run fine for a while, similar to your headache. It would start breaking up and losing power. I found that the Bosch coil was overheating because of it's resistance. I purchased a Petronix coil 0.6 ohms and 45,000 volts. The bug now runs fantastic!
https://www.summitracing.com/parts/pnx-45011/overview/
 
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