In a message dated 17/03/2004 11:33:09 PM Pacific Standard Time,
owner-mgs-digest@autox.team.net writes:
I've driven a couple of
other cars with a Weber DCOE (don't recall if they were the model 45) on
them and my experience is that low end power was lost and you had to rev the
Hell out of them to get any power. May be that these other cars that I drove
with the DCOE's weren't jetted/tuned right or something (one was an older
Alfa of similar engine size to the 1800 CC B engine) but I don't think so. I
personally believe it is a trait of the carb and its all out design for
power at top RPM.
First, the Webers that find their way onto an MGB engine are generally
jetted for something else. The Weber factory produces carbs for various
standard
Italian applications, and will sell you what you want ('you' in this case being
the vendor of the MG conversion kit), but many opt to pass the Webers on
unmodified. You thus end up trying to make a carb set for a Maserati function
in
an MG. Only with complete rejetting can this be done. Result - a lot of
conversions that run like crap.
The better vendors actually rejet themselves - to a set of specs that
represents somebody's ideal for use on an MG engine - but if you have a cam, or
higher compression, or live in Denver, you better go look for the guys that
know
how to retune Webers.
The idea of putting a single Weber on a street driven MGB that will rarely
see above 5000 rpm is ludicrous and happens only because too many people want
to have something 'racy' on their cars even if it does bugger all (or even is
detrimental) to performance. That also explains the use of that lacklustre
DGV conversion.
Now as to whether a Weber carbbed car only runs at top end, the answer is
yes and no. As most serious cars that have Webers tend to be tuned or racing
cars, they will run best in the higher rpm ranges no matter what you stick on
the intake. I had one hot 1622 engine we could never quite figure out. It was
13:1 and had a really whackingly hot set of cam numbers - it would run along
as if it were missing a couple of cylinders, and when it hit 3000 rpm, it
would light up, spin both rear tires and exit quickly - like an on/off switch.
It
ran SUs.....
There is no reason a Weber carbbed car can't have flexibility. My
Lamborghini (with 6 40 DCOE carbs) can be floored in 5th gear at 1000 rpm, and
will
pull from there smoothly to a (theoretical, in case there are any law
enforcement readers) top end of 165 mph. That's flexibility.
I run Webers on my TVR race car (still looking for a new home.....) and my
Twincam, and taking into account the fairly highly tuned nature of the engines,
they do not lack in flexibility. But then they run one barrel per port (the
TVR has an HRG head), which helps.
So I wouldn't condemn out of hand the Weber carb as unsuitable for
flexibility - it's just that most engines where they see use tend to already be
inflexible in terms of low range torque - if they weren't highly tuned, they
probably wouldn't bother with Webers.
Bill
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