Zenith vs Weber

[red-beard]

Can someone explain the differences between the Zenith and the Weber and any performance/maintenance issues of using a Zenith?

James

[billwagnon]

It's my impression the Weber is more of a "standard" and is more finely adjustable/rebuildable.

But that's all I know. Honest.

[red-beard]

Why did Porsche replace the Weber with the Zenith? The Zenith appears to have been used in 1970 to 1972. The Weber was used from 1965-1969.

I'm putting together a "spare" engine to use between my 1974 911 and 1970 914/6 while I successively rebuild those engines. I found a set of Zenith's for very reasonable money. Total cost for the linkage (new), manifold (New), Zenith, Carb rebuild kit and K&N air filters (New) is
$776.

James

[Tim Walsh]

I'm not really a carb man but I belive that they don't have any venturies other than the 27mm one that came with them. From what I've read they are pretty restrictive. Webers on the other hand have a large selection of venturies, emulsion tubes and jets where the zeniths do not. From what I've read the zeniths with 27mm venturies can only make about 160HP before they become the restriction in your engine.

[West]

I think that Webers are more suited to a race enviroment, but I prefer my Zeniths for the street. On Webers, the main jets and the air correction and emulsion tubes can be changed without leaking fuel onto your exhaust (big plus on the track). With Zeniths, you have to hold a cup under the side of the carb to change the main jets to "catch" the fuel leakage (takes more expensive track time). But, on the early Weber's you only had a 2-position accelerator pump, (either to lean or too rich). On Zeniths, you have adjustable accelerator pumps, although Weber did correct this on later models with adjustable pumps. I'am running Zeniths on a nicely built 2 liter, and there enough carb for the motor and I love them. Tens years ago nobody wanted Zeniths, I picked up what your looking @ (carbs, linkage, manfolds and k&n's) for 75 bucks!

[red-beard]

The Zenith's were $100. The rest of the stuff was the costly adventure.

James

[Randy Webb]

Weber tried to create a spare no expense carbureter.

Check BA's book for more info.

[red-beard]

BA ?

James

Mr. T from the A team?

[yelcab1]

Weber, the ultimate driving machine carburetors.

Got four of them sitting atop my Ferrari. Hard to tune, but once they are dialed in, they are IN.

[Stu Wilkinson]

Two sizes of venturi are available for zeniths, 27.5mm and 28.5. I have two sets of zeniths and have a set of each.
I have just put a 165 hp Euro 2.7 in my 70T, with an early exhaust... so it should be around 175hp.
I Lathed out one set of venturis to 31mm (yes getting a bit thin in one spot but OK just) and rejetted the carb according to recommendations used for webbers. The engine goes very well, and does not appear to be leaning out at high revs in fifth.
I believe Motor meister can supply even larger venturis.
My zeniths have been great. Sure they arent webbers but at a tenth of the price, and they do the trick nicely on lower horsepower motors.

[DonNewton]

BA = Bruce Anderson

[red-beard]

Well, the 2.2E is no barn burner. MM is supplying the gear to fit the Zeniths and to rebuild them. Again, my intent is to setup this 2.2E as a spare for my 914/6 2.2S and to initially run in my 1974 while I'm fixing the case studs, etc...

The Zenith Carb setup seemed to be a decent solution in place of trying to get the CIS working on the 2.2. Plus this will let me "drop" it into the 914/6 while I'm getting that baby redone.

James

[red-beard]

Originally posted by DonNewton
BA = Bruce Anderson

Thanks!

[jluetjen]

Well, the 2.2E is no barn burner.

The Zenith Carb setup seemed to be a decent solution in place of trying to get the CIS working on the 2.2.

Uhhh -- now you lost me. First off none of the 2.2's ever came with CIS. And compared to the tuning of most (all?) of the later CIS cars, a 2.2E is a pretty hot little motor with a 7000 RPM readline. (Take THAT SCWDP!!!). Even with it's relatively small 2.2 liter capacity it made more HP (and a much better sound) then a 2.7 normal. If by chance you are refering to the 2.2E's stock MFI system, it's good for 10 more HP then you'll ever get with the carbs, and they're not that bad to get set-up right. If that is what you do have, this BBS and the associated technical links have the best MFI information around. Period.

If your 2.2E seems like a lackluster motor it most likely needs a good tune-up.

[red-beard]

The CIS refers to the CIS in the 1974 with the 2.7 that needs serious attention.

If have not operated the 2.2 yet...working the fuel system right now.

James

[mb911]

I love my zeniths on my 74 2.7 I put 32mm venturis in it and bigger jets etc. wouldn't trade them for webers
Ben
77 911 3.0
75 914-6 2.7

[Stu Wilkinson]

Hi Ben,
You have a similar set up to me.
mine was a 77, 2.7
Out of interest, what mains, idles and air corrections did you use?
I have 130 mains, 60 idles and 185 air corrections.

Cheers

[mb911]

Mine is about the same except mains I drilled until I came up with the best results. The drill size escapes me though.

Ben

[Mukilteo911]

There are two types of Zeniths, one type was sold in US only and has an extra enrichment circut for overrun conditions. The other sold in europe did not has this circut. Does anyone know if you can modify the USA type to the Europe version ?

[mb911]

Yes by removing the enrichment circuit altogether. I performed this on mine and they work great. My car starts well when cold much better then my dads 356sc with zeniths on it. I do have a sketch somewhere of how to do this if intrested let me know.
Ben