Eureka!

[Niels Svane]

I apologize for the long text, but hang in there

So, I just want to update how it ended with my 845cc 4TL which had stalling issues, rough idle issues, poor damp starting issues etc. Nearly all problems came after two months of winter standstill.

Well, I changed all the ignition parts which helped the erratic poor starting issues.
It didnt do anything regarding stalling and rough idling.

Then yesterday I stripped the carb, and rebuilt it after cleaning. All jets etc seemed fine so I didnt swap anything.
After putting in back in its place, its just drowned the whole shabang until gas dripped out from the axle to the throtle valve....The mixture screw had no effect whatsoever suddenly.... I then went indoors to scratch my head, hate the world a little bit, and eat some lunch with a cup of coffee.
I then pulled the top of the carb once again, changed the main jet, the float and float axle, and readjusted the acc. pump. Along with that I pulled the mixture screw out cleaned its thread even more.

AAAND voila! It ran like a charm. I then set the dynamic ignition too, so its now a lot quieter and pulls even better.
It still needs a bit attention on setting the mixture and gas stop screw perfectly, as it drowns/dies a bit at the first small amount of gas-pedal travel.

Hopefully all this trouble may help another who has the same kind of problems
Im just glad I gained insight in stripping a carb and adjusting the ignition, so now it can be done in under half an hour.
Next projekt is finding every little spot of surface rust, grinding it of with my dremel, putting hamerite allover the place and spraying it in the original beige And also putting some hamerite under the car if it needs. Its actually surprisingly rustfree for a danish car.

 

[Niels Svane]

Hmm, now everythings fine and dandy regarding carb. and ignition, and fuel consumption is around 6 - 6.5l pr. 100km. As I see it, thats pretty good for a 845cc with acc. pump.
BUT it still hesitates a bit when picking up the throttle at speed, and a bit when pulling of from standstill too. It also seems somewhat sluggish between 95 and 100 km/h (might be the 34 hp ).
Ive tried different kinds of mixture and throttle stop settings but the hesitation prevails. If changing carb setting doesnt do much, am I then right to suspect the vacuum advance or ignition timing?
There is no restrictor in the vent pipes from the head to the carb, but would that be causing hesitation at speed?

The dynamic timing is set with a timing-light at 10mm before TDC. Should it be closer to the TDC mark instead maybe?

Thanks in advance! (the dying at sudden stops, and rough idle is completely gone still!)

 

[malcolm]

Are you checking the static timing with the vacuum advance disconnected (should be disconnected for the check).

Sounds like the car is running too lean or the advance isn't enough.

Is the vacuum advance working? You can check it by sucking on the pipe and see if the distributor base plate moves.

 

[Niels Svane]

Yep measured without vacuum advance
Ive checked it last day and it works fine, ie the mechanism moves somewhat with suction.
The problem is the same with a lot of different mixture settings, and seems to improve a bit with a bit of choke applied.
I have adjusted so the accelerator pump now applies a bit earlier, but I'm first able to test it tomorrow. Idle after a short run this evening is really low and smooth now So if the hesitation problem cant be solved Ill just drive as it is.

 

[Niels Svane]

By looking in the forum it seems that hesitation problems is a common problem. Both with zenith 32 and 28

 

[JonathanT]

This is probably off at a tangent but I fitted an electronic ignition . It made a really significant improvement to all the range with really perky pick up on throttle. I'd thoroughly recommend it it's the little green box on top of the coil on the left.

 

[Niels Svane]

No tangents are too far off What brand is your green box? I havent seen any that seems to be fit the 845, but maybe that doesnt matter?

 

[JonathanT]

I'll find out for you. Cost £40 which seems a lot for something the size of a matchbox! I had it picking up the pulse from the existing contact breaker. They no longer spark and it works great. But when Womble is back together I'll be using the little hall sensor which is contact less but will require a Little mod to the dizzy to fit

 

[Niels Svane]

Ill play around with the dizzy tomorrow, to determine if it is there the problem lies. More fiddling with the carb will do no good im sure

 

[Niels Svane]

As stated yesterday, the dizzy could be the culprit. So today i took a little testdrive until the engine was hot, and then advanced the ignition a bit, and drove off.
And it actually now runs with smooth sloooow idle, no hesitation at pickup, low consumption and reasonable acceleration (Above 85-90 its a bit sluggish, but I never drive at that speed anyway).