Cylinders not working after su conversion

[shadesh]

I apologize for throwing in that rather moot comment. It was meant to be tonge-in-cheek not derisive. Actually, I'm only a proponent of EFI systems on vehicles that were originally equipped with it. Do you have access to a tool like a Uni-syn or Color Tune? I've used both of those in the past to assist in balancing carbs.

no worries. I was a bit defensive there too. You have helped me quite a bit in the past with my EFI issues and has been appreciated.

I have to pick up the uni-syn from motorsport... so far I was just trying to guage the flow based on what I was hearing..

[shadesh]

Maybe the float bowls sits in different hights, still i think it is a adjustment problem, SU's are simple carbs and it seems that your front one is starving, so if there is no gasket leaks, i still vote for incorrect float hight..

Do you understand the SU function?

EFI the bastard:eek:

Chris

Hey Thanks.. I just saw the videos (2 parts). It seems that the float height may be the problem. I will re measure and adjust if necessary.

Does this mean that the float level is lower than it should be? or higher than it should be.. I know it needs to be level to something in the bell housing or the nozzle??

[ChrisZ]

As i understand it your float level is to low.

Good luck

Chris

[Arne]

^^ I agree, sounds like the level is too low in front float. To test that, you could try to adjust the front nozzle down farther. You said they were both set at 2 1/2 turns down. Try turning the front only an additional 2 1/2 and see if that's any better. If it is, that would confirm that the level is too low. Don't leave it that way, correct the level so that both adjustments are similar (they don't need to be identical).

[sblake01]

Do you understand the SU function?

EFI the bastard:eek:

Chris

What's not to understand? Perhaps the simplest carb ever produced next to motorcycle carbs. Do you understand the EFI function?

[ChrisZ]

I don't understand this!

What's not to understand? Perhaps the simplest carb ever produced next to motorcycle carbs. Do you understand the EFI function?

What i meant was that if he undestand the simple function of SU's he would also know what is the problem, at least 80%, witch i think he do by now.

And if it won't work he can always EFI the car.

Chris

[Bruce Palmer]

Don't forget to check that both carbs are opening together. We've helped too many fight problems only the find out they failed to secure both carbs to the center linkage.

Doesn't matter though cause you need new carbs anyway...... My standard friday afternoon answer.....

[sblake01]

I don't understand this!

What i meant was that if he undestand the simple function of SU's he would also know what is the problem, at least 80%, witch i think he do by now.

And if it won't work he can always EFI the car.

Chris

My apologies Chris. I thought those comments were directed at me.

[ChrisZ]

No sweat Stephen

[john mcgarvie]

I have to say i have the same problem. Only it is reversed the back one causes the miss. I swapped the carbs and the problem seems to be gone.

But i cant run like that no linkage. Ne ideas.

[shadesh]

I have to bring this thread back as I am having issues with tuning my carbs. I originally had the float of my front carb set a 16mm and rear at 12mm as it is required for 1972s. Also, set the adjusting screw at 2 1/2 turns.However, the front 3 cylinders were not working.

I then adjusted the front float level to 12mm. Set the adjusting screw 2 1/2 turns and still the same problem. BUT, when I set the screw at about 4 1/2 turns, the front 3 cylinders started working.

I set the air flow using the synchronizing tool.

What is the problem? Is the needle out of sync.? Please help.

[Arne]

I then adjusted the front float level to 12mm. Set the adjusting screw 2 1/2 turns and still the same problem. BUT, when I set the screw at about 4 1/2 turns, the front 3 cylinders started working.

The front carb's float level is still too low. Correctly setting the level can be tricky for the inexperienced. You need to bring it up another 3-4 mm, as a WAG.