SU Carb tuning

[SpqrEddie]

Hello,
I have measured the distance between "I" and "1 I 6", the mark "I" is 1 1/4 before the mark "1 I 6", so i can confirm that the mark "I" is the firing point.
Hopefully this can help 1959 CLB owners (in case these are factory markings!)

Eddie

[SpqrEddie]

Hello!
I am not still able to get the engine running right...
I am unable to get a stable idle. after a while it goes down to a point that then the engine goes off as is it too low.
As well it is very difficult to get the engine revving. I have to give little hits to the pedal to not flood the engine. if i push the pedal down the engine drowns and stops.
At times the idle seems fine, but then it goes down and the engine stops. This even if I set the idle speed higher.
To keep the engine running i need to keep give small trottle strokes, untill a point the engine finally is able to take the throttle and revs up. But then shortly after it goes down again.
Any suggestion on what should be the issue??

- I have between 95 and 110 PSI in all Cylinders.
- New Lodge NH Plugs with gap set as per Manual
- New Distributor Cap and Rotor Arm
- Distributor Points set as per manual
- Ignition timing set as per manual (no indicaiton on the revs on the book, i set it at 2500 RPM)
- New connections on the spark cables
- Foat Chamber level set as per manual
- New float chambers needle valves
- Few drops of SU Oil in the damper pistons
- needles centered in the Jets
- Approximative carburarion done ( 1,5 turn out and then adjusted from there)
- Approximative syncoronisation done (Hiss method, not very precise as per below i am not able to get the idle stable)

Thank you all in advance in case you have any suggestion!

Eddie

[Robin A Woolmer]

Have you checked if you have an air leak in the induction manifolds between the carbs & the head? this may account why you cannot get stable running setting up the carbs!
Robin

[SpqrEddie]

Hello Robin,
no! i didnt! i will try to buy an air leak detector spray anche check.
Eddie

[SpqrEddie]

i bought a can of ether starter. will try later.
I was thinking that may be is just fuel starving? may be the new needle valve are different? i didnt measure them, as i tought these were standard.
Or may be the float level too low? but then if set higher i belive it overflow into the carbs.

[AEX 31]

Hello,

After this last winter I’ve had great problems getting AEX 31 to run nicely, or run at all! What you have described sounds very similar to what I experienced. I tried loads of different things until I emptied the tank and put some new fuel in the car. As strange as that might sound that actually seemed to have solve the problems.

So I’m wondering if you have fresh fuel? The fuel in 31 was 5-6 months old. I’m in Sweden and 98 octane here has a 5% ethanol mix.

Maybe be worth a try getting new fuel?

Best Jonas

[SpqrEddie]

Thank you Jonas,
the fuel is fresh.. so i dont think is that.
Yestarday I tried to spry some ether around the carbs and i was not able to find any leak. May be there are, but i was not able to detect any.

As well, i tought that the issue could have been float bowls venting as i changes a well the 3 slotted fiber gaskets, but i tested the carbs without retaing nut so fully open to the atmosphere and no visible change, so i belive the floats breath normally.

may be the issue in the end is just that i am doing long static tests, and never did any tuning on the road as the car has no papework yet so can not go out.
And may be this flood the engine after a while. may be some soot builds up etc etc as the mixture is a bit rich, and in the end the engine stalls.

I will try to do the MOT techincal inspectio as is. and then try to fine tune it.

[Michael Trotter]

Eddie

I think your ignition timing is wrong. You tell us you set the AC figure (12.5 degrees btdc ?) at 2,500 rpm. But this is a static setting (we didn't have strobe lights in the '50's). Don't know anything about the centrifugal advance curve but I think it is running too retarded. Suggest you try the old trick of slackening the clamp bolt and turning the distributor in the advance direction with the engine running to see what that does. You don't mention evidence from the appearance of the plugs. Get it up to temperature, switch off and take the plugs out. Are they nice light grey/sooty black/oily black/petrol wet?

Hope this helps.
Michael

[SpqrEddie]

Hello Michael,
Thank you. Indeed this is one of the possibility, in fact part of the issues started after i touched the distributor ...

so instead of dinamic timing, i will do it static and thake if from there...

The plugs are a black, no oily no wet, just a bit rich i belive.

Thanks,

Edmondo

[SpqrEddie]

Dear Micheal and all,

I time it statically and it runs fine!

So it was definitely out of time. I did the static timing with a Lamp.
i took the plugs off, rolled the car over in 4th and set the points to open on the "I" mark on the flywheel (12.5 degree advance as per the manual).
I disconnected the condenser, and used a lamp. It goes off, exactly when the timing mark goes trought the hole in the clutch bell.

Now the car keeps the idle, and i have set it around 1000RPM.

As well the engine runs about 100 degrees cooler! so there was surely something wrong with the timing.

I will now tackle carb tuning again.

[10kph]

hello,
             Are the carbs from a saloon 1 1/8 diameter or fron an ace/aceca with 1 1/4 diameter. You definately need at least 1 1/4 chokes and even 1 1/2 dia for racers.
      I remember having your problem with the third carb lagging opening compared to the first and so used a piece of 5/16 inch solid brass rod instead of the spring. Later i realised that the spring needed reversing because the coil was wanting to unwind itself and creating lag.
     The weller engine is not about power but smooth torque which makes it a great engine and 9 to 1 compression should increase the torque unless the modified head has destroyed it !
   Regards
     Tony