I am just about there ten times over. lol Okay, so I am doing everything right as far as the procedure goes. I have already adjusted the linkage for having some minor wear. I even check the throttle plates when fully open with the car off after I get done to see if they are close to the same place.
I'm going to try for maybe 1200rpm and see what I can get. An air leak is possible. I removed a carb about 6 months ago for a leak between the carb and manifold. After I reinstalled it the car ran even better. Should have left it alone. I didn't know an adjustment was such an ordeal on these carbs.
Thanks again for the help and verification.

It's the first time I work with these babies but theoretically given a situation where the passages are restrictive causing a lean A/F ratio, the fuel not cooling the "barnacle", hot temperature from the engine and the addition of vacuum IMHO may cause a explosive situation.

If you suspect a vacuum leak you can always spray a touch of "Carb Cleaner" between the intake manifolds.
If you get the engine to idle to whatever rpm spraying this product on the area will cause the engine to change sound. This may help you pinpoint where the leak is situated.

Danpez, good idea. I'll try that.
I'm going to order some new jets. Got a question about that. Are Solex Main Jets, Solex Idle Jets, and Solex Air Corrector Jets what I need?

Okay, I found something tonight. While checking the accelerator pumps I found some raw fuel leaking between the manifold, and carb. I replaced these a while back, but apparently the gaskets supplied with the kit did not hold. They are too thin. Anyone know where I could get a set that are the correct thickness? Is the Victor Reinz gasket on Pelican correct?

Gaskets - Keep in mind you have insulators in there as well. You need to make sure you end up with the same overall thickness of gasket+insulator on each of the 3 cylinders/carb so that they all pull down and seal evenly.

Jets - They are solex, but I'm still confused whether solex mains are the same. What I do know works is to buy the idle jets from Gene Berg and the main or air correctors from alfa1750 on ebay.

Pmo will sell gaskets and they are thick. I think the old parts are not flat.

Doug the gasket / insulator that you mentioned would it be between the carbs and the manifold or between the manifold and the cylinder heads?
Because the kit does come with manifold gaskets and was wondering if I missed something.

http://forums.pelicanparts.com/uploa...1396715801.jpg

Alfa1750 will sell you mains for the zenith. I think they are the same as most solex

Btw zenith was made by solex

You did not miss anything. The kits come with carb to manifold gaskets, but they don't fit right from bolt to bolt. They are also not the same thickness as the old school gaskets. I had to modify the bolt holes slightly to make them fit, but they apparently did not hold.
Now, what insulators?

I have found the plastic insulator shrink a little over time. The middle seem to shrink more than the edges. I have sanded mine to reestablish a flat surface on both sides. But you must have calipers, because you have to sand them flat and to the same thickness

Zenith Tuning
 

I wanted to get all the geometry setup before firing the engine up again and was reading up on how to tune the Zenith carbs and according to the drawings / explanations I seem to be at an impasse to say the least. This may or may not make sense with the enrichment circuit hooked up.
Here is something to think about.
- Given the fact enrichment is active only when the micro switch is “ON” the A/F ratio is controlled when the throttle plates are completely closed by adjusting the Mixture control, Flow rate and Air Bypass control screws simultaneously. (diagram of Thread #13)
- Then the idle mixture control screws are adjusted when the throttle plates are ever so slightly opened so that the idle jet size and air passing through the emulsion tube make the correct A/F ratio. (Enrichment switch is "OFF")
- For the rest of its transition would be between the fuel coming from the main jet, pump acceleration and idle jet with air from the emulsion tube.

This is where I find the document diagrams a little confusing.

If the throttle plates are completely closed when the enrichment is active compared to the position of the plates when in idle …… what does the Idle Speed adjusting screw do? (Idle Speed screw should be a stopper for the throttle plates)

Is the idle speed screw used to adjust the throttle plates for when the enrichment circuit is active also?
Therefore on the enrichment stage the throttle plates wouldn't be completely closed as per the diagram?

If someone could shed some light it would be great,
Thanks

I think the issue is when we say the throttles are closed, it does not mean there isn't a gap between the actual plate and the throttle bore.

At idle, the throttle stop screw sets the bulk airflow and essentially idle speed.

When you lift off the gas, and the throttle plate close and stop rotating, they are sitting on the throttle stop (idle adjusting) screw. At this point the engine goes lean and the aux air enrichment system opens and allows air to bypass the throttle plates. Thus the idle speed is raised becuase more air is entering the cylinders. Properly set up aux air enrichment system
Willl also mix in enough extra fuel to richen the mixture to prevent the formation of NOX.

Mike .... that exactly what I wanted to confirm.
The functional diagram of the Idle system and Enriching circuit was confusing.
I imagined the Enrichment passages were designed to have the exact A/F ratio with the throttle plates completely shut. (Literally)

The enrichment circuit does have to be adjusted to have acceptable AFR. The big screw right in the middle of the manifold (barnicle) sets the air flow. The smaller screw just upwards and to the right of the manifold adjusts the fuel flow. I never did this, I removed the system.

as far as air leaks are concerned when I rebuilt my carburators I had to have the intake manifolds machined. It was interesting to see the machine shop had to take almost 1/2 mm out to get them flat. They bend on the engine end and I believe the reason is that the phoenolic insulators compress over time where due to the nut load. When rebuilding the carburators it's definitely worth it (I'd say mandatory) having them machined.
luca

Where is the insulator? My car just had a regular thick paper gasket under the carb. Are we talking about under the manifold in the photo above? Someone explain please.

The insulator goes between the manifold and the cylinder heads. Two gaskets are used. One between the head and insulator and one between the insulator and the manifold.

If the insulator is not flat ( potentially cupped due to shrinkage) either or both gaskets can leak. Especially over time.

I installed a new set of gaskets and the car was fine. Ten minutes later it started to pop. The gaskets failed that quickly. I removed the insulators and sanded them flat and reinstalled with new gaskets. Much better.

My experiences would say anytime you go from a good idle to popping you should look for leaks. They are insidious and misleading. I had both a bad exhaust and intake gaskets on one cylinder.

Things move about, and over time gaskets can leak.

I spent the most of 2012 chasing air leaks. New manifolds from PMO with the base shaped to match the SC ports solved the problem.

Curil-T between the throttle body to manifold gasket solved the leak there, although separating the carbs recently was much harder because the seal was so good.

Get rid of it, you don't need it and there is a risk of fire...