....and Alex spake unto the tribes of Usenet, saying...
> On Thu, 15 Dec 2005 19:35:51 -0000, "Graham G" <NOSPAM@here.com>
>> Brother got his IIa up and running today, however he tells me that
>> its running like a bag of spanners!! He says that it ticks over
>> fine, but under acceleration it misses and chuffs out black smoke.
>> Has turned the mixture screw right in, and it will continue to run
>> and accelerate with black smoke. Economy diaphram has a small tear
>> in it, is this likely to be the cause?? He also seems to think ther
>> is excessive wear around the hole through which the shaft holding
>> the flutter valve sits (apparently petrol comes out rount here, but
>> he thinks its a result of the huge amounts of fuel being dumped into
>> the system).
>> Should he get a repair kit? Is it something he's missing, or shoud
>> he just throw it in the hedge and buy a new one?
>> Any help is appreciated as he is baffled ATM.
> I had a lotta trouble with a Zenith/Stromberg carb on my IIa, despite
> a rebuild with an overhaul kit, it still did strange things. I
> replaced it with a brand new Weber, not had a single problem since.
> Apparently they can have problems with warped carb bodies, something
> to do with problems during casting.
The original Zenith on the 2a was well knackered, so I replaced with a
"Zenith type" (ie pattern) carb from Cra/Paddocks. It lasted a few months,
by which time it was so warped it would hardly run at all. The gap between
the lid and body on the front edge was over 1mm in the centre. Flatting the
mating surfaces on fine emery on a glass plate helped but didn't cure it.
Alex is right - it's something to do with the heat-treating during
manufacture, and there are a lot with this problem AIUI. It would not idle
evenly, even when set to idle at >1000rpm, ran extremely rich, and turning
the mixture screw in and out made no difference. I bit the bullet and got a
new genuine Zenith (now being manufactured by Burlen www.burlen.co.uk
pricey, but runs like a dream now.
Disco 300 Tdi auto
S2a 88" SW
Tiggrr (V8 trialler)