Help: Zenith Carburetors. No wonder it didn' run well !

[Allen Henderson]

Carburetored guys,

Recently, I purchased a very straight and rust free Palm Springs '70T. I'm fixing it up to run and drive well. As you can see one of the shaft couplers has broken; no I didn't do it and no wonder it idled well but seemed to be missing as two throttles were not opening! Not to mention the accelerator pumps, etc were all dried out. Two questions:
1. Can someone supply me with one of these couplers? I don't know, but it LOOKS like the Weber one but may not be the same. Does anyone know?
2. Tougher question..most probably for California smog knowledgeable folks. Look at the epoxy on the auxiliary enrichment valve. This epoxy blocks off the valve from working. AND the other valve on the other carb, has the same thing! This valve is supposed to work to reduce emissions on closed throttle overrun conditions, like going down a hill. IS anyone aware of problems with this valve and a car running nicely? It looks like someone wanted to defeat its operation without smog inspectors being able to see what they'd done. That's my guess. Should I fix it, open up the closed holes? Thanks!

-Allen-

[edmayo]

Allen, might have what you need, let me check our Zenith "bone yard" As to the emission diaphragm I have always left them operational, and in fact they are on my own 71 T. It's only a problem if you burn through that diaphragm, and if you do #'s 2 & 5 will have an idle miss. The diaphragm always came in the rebuild kits so I always used them. I rebuilt my current Zeniths when I got this car in 01 at 131,000 miles. It now has 186,000 and I've readjusted the idle mixtures once. They sure are finicky carburetors !!!! LOL

[smedley]

Hi Allen,

I ran the Zeniths on my '70T back in the day. Stoddard sold a "sport kit" for 2.2Ts which was a set of custom machined 34mm venturis, appropriate jets, an E dist rotor (7000 red line), and foam Filtron filters. They recommended a twin pipe sport muffler, but I ran the stock single Leistritz on the street and open megaphones on the track. There were no other modifications recommended aside from venturis and jetting...stock enrichment, left wierd air balance tubes intact, etc. With short gears car ran like scalded rat. Stoddard claimed 35-40 hp which sounded like alot, but the stock venturis were 27mm which strangled the motor, and the way the car ran I tended to believe their claim. The kit was cheaper even then than a pair of Webers. The Zeniths were just fine...many time trial trophies including Parade. If you can find parts, they're OK. Hopefully Ed can help. Mark

[Allen Henderson]

Ed, would be GREAT! if you can help me out. Mark, no doubt the T was detuned by the factory. I vaguely remember the Stoddard kit; sounds like the earlier factory sport kit that a lot of the rally cars ran. Thanks!

-Allen-

[Allen Henderson]

I received the below information from Paul Abbott of Performance Oriented http://performanceoriented.com/ Thanks Paul! So, again, I hope I can find a Zenith coupler.

"Yeah, gotta remove a butterfly to replace shaft coupling. The Zenith couplings are not interchangeable with Webers, the Webers have a reduces shaft diameter for the coupling where the Zeniths have an 8mm bore.
<<<<<<<<<<>>>>>>>>>>>>
Since your car is pre 1975 then the "high speed engichment" feature is routinely blocked off like previous owner did and should pass Calif smog inspection that way. Lots of info regarding Zeniths on the Pelican Tech forum if you look there." ...Paul

[obrut]

Allen,

Nothing to add - aside from some encouragement.

I recently picked up a (75000 mile) 2.4T running its original Zeniths. They had clearly been 'adjusted' by someone unfamiliar with them. My mechanic set them up correctly and the car now runs like an absolute champ. Rock solid idle hot or cold, easy starting hot or cold (following the procedures in the manual!) and a smooth pull to redline.

If you perservere and get them running as intended I'm sure you will be happy with them.

[chiroracer]

I was always happy with my zeniths until I tried to hotrod them.Wish I would have known about the stoddard setup. I had a few carb fires though,I would use some insulators from pmo for sure. Steve

[tom1394racing]

Alan

PM me if you are interested in a quick and dirty fix for the broken shaft coupling problem.

[Allen Henderson]

Ed, would be GREAT! if you can help me out. Mark, no doubt the T was detuned by the factory. I vaguely remember the Stoddard kit; sounds like the earlier factory sport kit that a lot of the rally cars ran. Thanks!

-Allen-

Thank you Ed for helping me out with this hard-to-find part. I've sent my carb body up to Paul at www.performanceoriented.com At least one butterfly throttle needs to come off and although I often attempt such things, I didn't want to mess up my otherwise nice carburetor. Thanks.

-Allen-

[teenchy]

Stoddard sold a "sport kit" for 2.2Ts which was a set of custom machined 34mm venturis, appropriate jets, an E dist rotor (7000 red line), and foam Filtron filters. They recommended a twin pipe sport muffler, but I ran the stock single Leistritz on the street and open megaphones on the track. There were no other modifications recommended aside from venturis and jetting...stock enrichment, left wierd air balance tubes intact, etc. With short gears car ran like scalded rat. Stoddard claimed 35-40 hp which sounded like alot, but the stock venturis were 27mm which strangled the motor, and the way the car ran I tended to believe their claim. The kit was cheaper even then than a pair of Webers. The Zeniths were just fine...many time trial trophies including Parade. If you can find parts, they're OK. Hopefully Ed can help. Mark

This is the first I've heard of this kit but then I'm not long in the early 911 world. I'd love something like this for my 2.2T; will keep it in mind once I've sorted everything else out.