[BMWCSRegistry] Weber 38/38 vs Zenith 35/40

[Bowman Gray]

I had the same issue with my 32/36s - previous owner had done a poor  
job with the linkage.

On May 25, 2007, at 11:40 PM, paul.briggs at att.net wrote:

Interesting.  I had an incident where the previous owner had  
installed the 38/38s, and at about 1/2 throttle it stuck a bit, then  
when you go passed that it seemed to pick up power.  One night, after  
I had the car for a few months (6+ yrs ago) the throttle stuck open.   
That was a shock!   A few days later my mechanic in Dallas said the  
linkage were installed incorrectly.  He worked on them, and now it is  
entirely smooth from idle to full throttle.   I don't mean to offend  
(and I did not work on the linkage myself on my car), but are you  
sure yours are installed correctly?  I'm going to look at mine in the  
morning, but I am pretty sure everything opens up under full  
throttle, and I know there is no "step" or point of resistance in  
advancing the throttle.


- Paul

-------------- Original message from M Thompson <m_thompson at ids.net>:  
--------------


 > My only comment is that the Zeniths have a vacuum operated secondary
 > throttle. The mechanical force on the gas pedal is constant as you
 > push down. The Webers that I installed have a mechanical secondary
 > throttle. The force on the gas pedal is OK until about half way. I
 > then have to really push to get the secondaries to open. Not quite as
 > smooth as the Zeniths.
 >
 > I put an inordinate amount of time and parts into the Zeniths and
 > never got them to behave correctly all the time.
 >
 >
 > At 02:08 PM 5/25/2007, paul.briggs at att.net wrote:
 > >I hate to ask this given the fact I have the Weber 38/38s on my 74
 > >3.0CS, but, if both are in-tune, clean, etc, which performs better
 > ; > across the full RPM range: Zenith or Weber?
 > >
 > >I've spent countless hours reading up on carbs, lots of $ with my
 > >old mechanic, and at the end of the day (with an MSD ignition), my
 > >Weber 38/38s on a stock motor idle very nicely, have tons of torque,
 > >but absolutely no power above 4000 RPM.
 > >
 > >Sure, they're run up to 6,000, but it is slow going above
 > >~4,000...the engine just runs out of air. I'd love to have a
 > >powerplant that had a nice pull all the way up the powerband, and
 > >comparing the 38/38s, it would seem that the 35 / 40 Zenith is
 > >better suited to provide some nice low end response (35 vs 38, so
 > >maybe a bit less torque than the Weber), but at the top end the 40
 > >vs the 38 allows more air, so you get a better top end, all  
things being equal.
 > >
 > >Has anyone drive a coupe both with Webers and Zenit hs, both in good
 > >repair, more or less back to back and could comment on how the
 > >Zeniths delivery the power across the RPM range? I suppose one
 > >alternative is to just drop more modern motor with fuel
 > >injection...but would my coupe have better power delivery across the
 > >RPM range if the previous owner had rebuilt the Zeniths rather than
 > >popping Webers on the car?
 > >
 > >- Paul
 > >
 > >'74 3.0CS
 > >'73 2002rtii
 > >'95 540i / 6spd - VERY NICE, AND FOR SALE (see listing on Roadfly)
 > >_______________________________________________
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 >
 >
 > Michael Thompson
 >
 >
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