Zenith vs. Weber 34ICH

[Daurie]

My truck came with a Weber and a spare Weber, and a Zenith. What are the pros and cons between the Weber and Zenith? I'm planning on putting the Zenith on to do my own comparison but wanted a few opinions as well.

Thanks!

Daurie

[Daurie]

Since I got no responses here, I'll respond to myself and update my findings. lol.

I fitted the Zenith today and found a few things. As far as the running difference, The Zenith seems to have better low end power than the Weber for sure as well as noticeably smoother acceleration . I haven't had a chance to get it out on the interstate but I suspect it will offer less top end power than the Weber. My Weber would pull along at 65 mph with no fuss, but sub par fuel milage. Over the next week or so I plan to watch the fuel economy of the Zenith and will report back. I approximate I was getting around 12 mpg with the Weber. Which by the way, in the Weber I was running a 190 air correction jet, 165 main jet and F6 emulsion tube. A 160 main may solve a flat spot I had from 1/2 to 3/4 throttle. Full throttle pulled good but I suspect it was slightly rich.

The only issue I had with the Zenith was getting a smooth idle out of it. As I adjusted the idle mixture to where I thought it should be, a popping out of the exhaust began to re-appear. I've been chasing that pop/miss for quite sometime and I had it pretty well tuned out with my Weber. After adjusting the timing a bit and ending up back where it started I began to richen the idle mix. screw and minimized the pop and seemed to smooth out the idle somewhat. Retarding the timing some eliminates the pop/miss but I suspect I will be richening it a bit more as my timing is just a hair over 2 deg advanced, doesn't seem like much advance, but I seem to have good power.

[gudjeon]

I've run Zenith for years and its the only way I will go.

[Les Parker]

I've tried both on the Air Portable, and I am convinced the Zenith is the best for all round use.
On Vermonts roads (not Interstate), it cruises nicely at 55 mph and returns around 16.5 mpg, whereas the Weber managed 52 mph and only 13 mpg.
Fair enough, I had to reface the Zenith Spring and Autumn and a new float and accel. pump, but it started first turn of the key this weekend after being stored all winter, a fair boost to its staying in my possesion for a while longer.

[JayGoss]

+1 for the Zenith if you can get this sorted out. I've driven rovers with both Zenith's and Webers and when they are running properly the Zenith makes the car run much better- I concur with my friend Les.

One thing to keep in mind is I've had experience where the body of the Zenith distorts over time with heat. I had some issues a few years ago with rebuilt Zeniths that were coming to the states at that time. I was working with a well-known & experienced Rover repair shop/off road center in VT and they had to change back to a Weber after going through 2 rebuilt Zeniths due to warping, causing air to "seep" into the mix. The symptom was: rough, difficult to tune idle. The frustrating part was I was able to experience about 2 days of smooth running Zenith bliss before engine heat distorted the carb body and the rough idle would rear its' ugly head. The repair shop manager was disappointed and remarked that he thought "they" (the carb rebuilder across the pond) had sorted out that issue- which led me to believe that it was a well-known problem. I got the sense that it was an issue with the design of the Zenith- and that mating surfaces needed to be machined properly as part of a rebuild. There may be other processes that the rebuilder neglected to undertake (some sort of heat-treating, annealing or tempering of the body prior to resurfacing perhaps)- but the shop I was working with didn't think it was worth the effort to rebuild an "already rebuilt" carb...they stuck with the K.I.S.S. method and installed the Weber when all was said and done. This may have been because I had exhausted my Rover repair slush fund and it was time to get her on the road. I'm wondering if yours could be be warped and in need of refacing? I think it's worth spending some time trouble shooting as you'll be very happy if you can get the Zenith in proper working order. The nice thing is you have a spare Weber to keep you Rovering in the meantime.

[sven]

I like the Zenith too. Very easy to work on.

The Zenith service bulletin that RN has posted as a sticky is an excellent resource for this carb. Ive used it to troubleshoot mine

[TedW]

Mt truck (1970) came with a Solex, which I replaced with a Zenith. It ran great for a short while but the choke mechanism froze solid. I replaced it with a Weber which has run well.
My new engine now has the hottest thermostat. If I switched back to a Zenith might this eventually contribute to the warping you have described?

[JayGoss]

Mt truck (1970) came with a Solex, which I replaced with a Zenith. It ran great for a short while but the choke mechanism froze solid. I replaced it with a Weber which has run well.
My new engine now has the hottest thermostat. If I switched back to a Zenith might this eventually contribute to the warping you have described?

Not sure Ted (sorry). In looking at Les' earlier posting he resurfaced his Zenith to get it back up to snuff. It may just be a necessary part of periodic maintenance for the Zenith. In my case heat was the culprit for the distortion- although I'm not sure if it has been narrowed down to certain temps where one could say the higher the heat, the higher the chances of distortion. I'm hoping someone with a little more experience than I can chime in on this one- I'm not sure how much hotter the air temp near the carb gets when one uses a hotter thermostat. My thinking is the "offending" heat comes from the exhaust manifold- not necessarily the engine block. One thing to note is my rover had the heat shield installed- not sure if this actually "funneled" heat upwards to the carb while it was protecting the clutch/brake reservoirs- which in turn made the warpage issue more likely. This is speculation- perhaps someone can add their expertise...anyone?

[Daurie]

I had seen many reports about the Zenith warpage issue. I have the 4 row radiator and an 84 deg thermostat so I hope things stay cool enough to prevent that from happening. I had the 74 deg tstat but my gauge never got near normal temp. My Rover is my daily driver so whatever runs best around town is what I will go with. So far I haven't even driven enough to get the engine up to temp. ! Everything I do is within a mile or two of home.

I did check for vac. leaks around the base of the carb and it seems like there is a small leak where the throttle plate rod exits the carb body, which is suprising seeing as the carb is brand new! It is a very small leak so I'll see how things go and may or may not address it.

[Les Parker]

Following on with the warpage string, it has ben found to occur at all tempratures, just an inbuilt idiosyncrosy of the Zenith carb.
Not a bad part to rebuild of a rainy evening, but worth the effort and inconvenience.