Is my engine really at TDC?

[Stevehose]

If the vacuum tube is hooked to the ported side of the carburetor (above the throttle butterfly) then yes. If it's below the butterfly, it's manifold vacuum.

Did you correct the leaking secondaries as indicated in earlier posts?

Does the vacuum port on the carb get fed just by the primary ? Maybe my secondary is stuck open somehow. That might make sense.

 

[Peter Coomaraswamy]

probably has nothig to do with it

but... I had gone round and round with my idle problem and for me-this is embarrassing-it turned out that I had incorrectly connected a small spring to the front carb linkage, which in turn jacked with the bottom throttle plate. As soon as the spring was removed things were much better and timing etc was set correctly. My momma raised a brain surgeon, it just was not me.

 

[Arde]

inaccurate ! siesta is a matter of all mediterranean countries, including south of italy
must be something else ...

Webers were made in Bologna, the North, where Edoardo Weber started.

No pun intended, I rest the case for the siesta.

 

[David]

If the vacuum tube is hooked to the ported side of the carburetor (above the throttle butterfly) then yes. If it's below the butterfly, it's manifold vacuum.

Did you correct the leaking secondaries as indicated in earlier posts?

I thought I did. I removed the carbs and gapped the secondaries at 0.002. But when I adjust the idle speed on one of the carbs, the vacuum will come down but the flow (measured with a synchromoter) doesnt come down much at all. Im guessing that this means the secondary on that carb is still leaking. Ill have to take it back off and check. Other than the secondary throttle plate, is there any other source of a leak like this ?

 

[David]

italy vs. spain ?
ha, ha, ha
how can you tell it is a spanish casting ?

The carbs are cast with the country of origin. Here is an interesting post on the topic:

http://genuineweber.blogspot.com/

But lets not take this thread off topic. We need to keep this thread for future owners that try to keep their carbs.

 

[David]

but... I had gone round and round with my idle problem and for me-this is embarrassing-it turned out that I had incorrectly connected a small spring to the front carb linkage, which in turn jacked with the bottom throttle plate. As soon as the spring was removed things were much better and timing etc was set correctly. My momma raised a brain surgeon, it just was not me.

Glad you got it sorted. Ill take a look. Much more of this and Im just going to get a new carb from Mesa.

 

[pamp]

The task is admirable....yet some day drag you kicking and screaming to EFI.

 

[deQuincey]

Webers were made in Bologna, the North, where Edoardo Weber started.

No pun intended, I rest the case for the siesta.

 

[61porsche]

It's not the measurement

Of the clearance in the bore. Measure form the plate surface to the throttle plate.

Assuming a nominal butterfly plate thickness of.06, the plate would be .02 above the surface or two thirds closed.

The plate is not open, only sufficient to not stick.

 

[David]

Doesn't the measurement at the bore determine the air flow through the secondary at idle ? I think you are suggesting a measurement of clearance between the throttle plate and the spacer plate. I'm confused as to what that would do.

 

[David]

Progress

I rebuilt the carbs: gaskets, o-rings, mixture needles, jets, reset the floats, replaced the factory throttle shaft bushings with bearings and went from a 50 to a 55 idle jet on the primary and secondary. I also set the secondary to 0.002"



Using Steve's instructions, I was able to get the car running again. In the photos below you can see the carbmate shows the carbs synch'd at 0" in Hg, but the synchrometer shows that damn Italian carb is still pulling more air than the other carb. What am I doing wrong here??



Rear carb: "The Spaniard"



Front carb: "The Italian"


Rear carb: "The Spaniard"


Front carb: "The Italian"


Sounds better, but still not as nice as deQuincy's.

 

[deQuincey]

hi david,
sounds much better now, good job, your exhaust note seems high to me, but it might be the exhaust system, or the camera mic, anyway it is much more equilibrated now
to my eyes, i recall my carbs, both, giving a suction figure of between 10 and 14
in the synchrometer, both the same value
regards

 

[Stevehose]

What are the readings on the dial gauges - zero?

What vacuum ports do you have the carbmate and the dial gauges hooked to?

Those Synchronmeter readings are from the secondary throat, yes? If so what are the primary readings?

Am traveling and can look at this tonight upon return.

 

[Luis A.]

A lot of valuable contributions on this thread so I'll offer my .02 but take it with a grain of salt. My first reaction upon listening to the last video is that not all cylinders are firing. Pull each plug wire one at a time and see if there is one that elicits no change.

 

[sfdon]

Could it be a lean misfire?

 

[David]

What are the readings on the dial gauges - zero?

What vacuum ports do you have the carbmate and the dial gauges hooked to?

Those Synchronmeter readings are from the secondary throat, yes? If so what are the primary readings?

Am traveling and can look at this tonight upon return.

Carbmate is hookedup to the vacuum ports off the carbs. Here are the readings from the synchrometer off the Italian carb. At idle, what should the primary and secondary be reading, ideally ?

 

[Stevehose]

It varies, but at idle I'd say 3-4 on the primary and less on the secondaries. If your primary is very high then likely your throttle butterfly screw is in too far (not the mixture screw, although this may need adjustment once that throttle plate setting is correct). If your secondary is high then you are leaking air past that throttle plate from previous discussion.

 

[David]

Could it be a lean misfire?

You and Luis were right. I had inadvertently leaned out the front carb too much. You both have some pretty well calibrated ears.

Other than the throttle plate, where else could I be getting an air leak from the carb itself ?

 

[Stevehose]

An air leak won't show up on the gauge as a higher reading, it would give a false gauge reading (too low) because if you plugged the leak it would then draw more air through the gauge.

Typical air leak spots are carb-to-manifold gasket, manifold-to-head gasket, worn throttle bearings, interior carb-body gaskets (Zenith has them, not sure of your Webers), uncapped vacuum ports both on carb (ported and below the throttle) and manifold (underneath where the EGR stuff was, etc.), leaking vacuum hoses, leaking distributor vav unit, leaking secondary vacuum actuators, and leaking choke pull downs if those are vacuum actuated.

I am starting to think the mix of Spanish and Italian carbs is part of the problem because they are not a matched pair. Either way, they are somehow out of adjustment. I feel your pain.

You and Luis were right. I had inadvertently leaned out the front carb too much. You both have some pretty well calibrated ears.

Other than the throttle plate, where else could I be getting an air leak from the carb itself ?