I need a Zenith Guru
 

I have a 1970 911 T. The car was idling poorly with frequent backfires from mainly the right carb. I did note that nothing changed when I adjusted the Throttle stops.

So........ after reading many of the forum postings I decided to adjust the Zeniths. Big mistake!! I followed the manual specs for base adjustments. Now the car will not idle at all. the only way I can keep it running is to pump the accelerator frequently. Needless to say, I am unable to make any further adjustments because the car won't idle with or without the throttle linkage attached. HELP!!

Did you make your initial adjustment with the linkage disconnected? What type of balancer are you using? This type usually gives better results;
Pelican Parts - Product Information: PEL-TOL-STESK
Ones that allow reading all three tubes at the same time are better still.

The car initially idled poorly. I moved the throttle stop screws in and out without any change in the idle speed. I then reset them back to their original positions. Disconnected the linkage and turned the mixture screws all the way in.. then backed them out 2 1/2 turns. I turned the air flow screws all the way in. Started the car and it won't idle.

first off, zeniths came with pretty small idle jets, like 0.45 and 0.50. you will have better luck with 0.55. same as used in vw bug solex carbs. way less spitting and popping, after they're adjusted right of course. idle speed 1000 when you do the adjustments, or you won't notice much.

Not trying to steel the thread but were is a good place to get a set
of 0.55 idle jets?
Thanks
Mike

either get a set of jet drills and use a micrometer on them to be sure or a vw shop or a supplier like claude's buggies. best to check them with a jet gauge first, cause just because they say 0,45 on them, doesn't mean they haven't been drilled already.

I'll check the jets. Any other thoughts on getting the car to idle so that I can balance the Zeniths ?

Hi Mike

Her's a good place for idle jets

SOLEX,ZENITH TIN IDLE JET | eBay

55s work well

Barry

When was the last time the Zeniths were rebuilt? It could be dirt plugging, carbon, rubber hose break down and other issues.

Did you open the idle screws more than 2.5 turns? 3?

Air leaks, shaft wear, gasket leaks all can make it run lean. There are many possiblities. In order to help you, please list all the things you checked and the service history.

The car was sitting in a garage and not driven for almost 10 years. Certainly no service or repairs during that time. Since I've had it, I drained the gas tank, changed oil and filter, changed points and plugs, replaced the fuel filter, reset point gap, dwell, and timing. No major problems until I changed the Zenith settings .

you might want to take the tops off, remove the floats and see how much silt, etc, is in the bowls.

And yes . I did try opening the mixture screws to 3 full turns with no significant change.

Mr. Walker-
I checked on Claude's Buggies website for the solex idle jets. they have Jets listed as part #3294 that are specific for a "Dual Solex 34mm Carburetor". they have a disclaimer that these jets will not fit a stock solex carburetor. Will these fit in my Zeniths ??

Thanks Barry I will contact them and see if I can get a set of 55s

Thanks
Mike

no, those are different carbs than the stock bug carbs. anything from the 50s to the 70s that was stock on a bug has the same style idle jets as the 911 zeniths. just different size holes in them.

Thanks ! I'll keep looking.

Idle jets
 

Gene Berg in So Cal
GeneBerg.com Parts Catalog: Solex Idle Jets

Alfa1750 on Ebay has fantastic prices and will give you a deal if you order several. Best price I could find.

http://forums.pelicanparts.com/porsche-911-technical-forum/562384-source-new-zenith-tin-jets.html

Yes go to ebay and buy them from Gabriel David.

When you adjusted the screws, you probably loosened up some crud. Now it may be blocking the hole.

10 years sitting, then you add new gas. Maybe a little E10. All the old crud is now being dissolved in the fresh fuel (with a nasty addition) and floated through the carbs. Sorry to say; it make sense just to tear them apart, clean, and rebuild.

While that is being done you could upgrade to #50 idle jets.