Triple Webers not running right

[bpmjg3]

Hi fellow Z enthusiasts,

 

I’ll start off by listing my specs:

 

1973 240z

L24 w/ Triple Webers

*all smog pertinent items have been removed/blocked*

 

I had SU’s that crapped out on me about 9-10 months ago so I decided to grab some triple webers as a nice upgrade. The car ran fine when first installed and tuned up. However, after that it sat for a about 4-5 months while I was in another state for work.

 

Current problem:

 

Once started, it does one of two things:

1. Revs high mid 2’s to 3’s

2. Idles fine

 

On throttle

Full quick throttle presses:

1. It has an absence where it doesn’t rev at all, almost like there’s a popping.

2. It drops a little

Slow throttle presses:

1. It starts to rev high and won’t drop until I press the throttle again hard and quick to recreate the popping from the previous.

 

Things I have done:

1. I tried resetting idle screws, air mixture screws and then tuning from there.

2. I pulled the Weber’s off to check to see if the throttle plates were shutting correctly.

(It seems that on quick throttles the linkages and plate return to fully closed, however, on slow presses and releases it tends to stay open 1cm. It closes by pulling up on the linkages again)

 

I purchased these carbs from Z Car Depot and have never had a problem with them before. So I know the quality and authenticity is there. They didn’t come with a return spring or external arms.

 

Is it a problem with them not returning properly or that my carbs are running way to rich? (Which I’ve tried to trouble shoot to no avail)

 

Thanks,

Matt

 

 

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[240260280]

http://240260280.com/Tech/Carbs/Weber/DCOE Theory Operation and Tuning.html

[bpmjg3]

Already went through this. I’m pretty sure it’s either the parts are messed up from sitting or I need some carb return spring.


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[jonbill]

Each carb has a return spring, I think it's under the cover on the manifold face of the carb. The linkage should also have a return spring. (the carb springs are strong enough to return the carbs not the linkage)

 

I'd take each carb off and make sure they open and close properly on their own before investigating further.

If the carbs open and close OK then your linkage is binding up somewhere. It may just need a return spring or it may need adjusting. Or both.

The page linked above (or alt least the books referenced there) have guides for correctly setting the linkage.

 

 

[munters]

It is possible to operate them without any springs but it depends a lot on your linkage. It looks like you need one in the state it is now.

Popping is lean not rich.

[bpmjg3]

I’m going to pull them off again and do a more complete inspection. I’m going to be getting some SU’s to throw on so I can just drive/move the car, double check timing and points etc.


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[xtravbx]

I'm new to the world of automotive cars. But I have a LOT of motorcycle carb experience.

Idling properly but not being able to accelerate under heavy throttle (bog, popping) generally means your mains got dirty / clogged from old gas.

 

I could be out of line here since I haven't torn into Webers yet - but if they are like any mikuni / keihin, your mains are clogged.

[240260280]

What is timing set to?