1972 Merc 250 - Zeniths & Webers
Hi from Down Under,
We've got a 1972 Merc with a 130.923 engine and the dreaded Zenith carbies. The engine has been rebuilt (home project because the cost would have been prohibitive at the Merc dealer and the mechanic who originally started the job was incapable of finishing the job). We're on the home stretch now dealing with the carbies. The Merc has been off the road for the last 2 years. Our only mistake was having yet another mechanic (who was obviously not a Zenith expert) do the final tune. That happened before I found this website and saw the advice about keeping non-experts as far away from Zeniths as possible! The car starts immediately and idles fairly quickly (auto choke) and then suddenly dies. This seems to occur once it has warmed up. It can be restarted but the accelerator needs to be depressed in order to stop it from stalling.
We have put premium unleaded high octane gasoline in the tank (Shell Optimax). When the car was on the road, I used to fill it with leaded petrol, now Australia no longer has leaded petrol but lead replacement petrol and for the last 2 years or so we've had premium unleaded petrol (98 octane) in the market place. We filled the Merc with Shell Optimax and I'm hoping that this isn't contributing to the problem. I remember that my Merc was very fussy on the fuel and that I always filled at the same petrol station. What octane level are people using? Have we done the right thing?
I'm hoping that something has been wrongly adjusted by the mechanic and that we can rectify it by following much of the advice that has come off various threads on this site. I've also got a copy of the Zenith carby manual - via a post on this site which contained the link.
However, I've had carby problems for a number of years and even the dealer has never really got them right (with lots of $$s having been spent). This website has been fantastic and it is a pity that I found it only recently as it really would have greatly assisted my father who has done a fantastic job with the engine (and the Haynes manual). He also agrees that the manual can be very misleading.
We've seen much of the advice and comments on Zeniths as well as the comments on Webers and looked at the Jam Engineering site. We are just exploring options at present given the carby problems. Can anyone advise what cars have had Webers that could be used to replace Zeniths? What model of Weber would suit? What manifold would fit a 130 engine, that would also suit Webers? Any information on conversion would be very welcome. Visits to wreckers yards in Australia may be our only option due to Australian exchange rates. Any views?
In my surfing (not this site), I came across a post from an Australian BMW owner who had Zeniths (with lots of trouble) and had changed them to Webers. He had made a comment that Zeniths were unsuited to the heat we experience in Australia and more suited to colder European climates. He was very impressed by the Webers. That view, in conjunction with some of the feedback we've seen on the Webers (and conversions), makes us think that this may be the way to go.
Any assistance would be most welcome.
Regards, Jennifer & Tom