In a message dated 16/06/2005 8:50:08 AM Pacific Standard Time,
matt@trebelhorn.com writes:
So, if you accept that everything he says about the DCOE vs/ SU
question is true (I'm trying to play nice), the only advantage to going
with a DCOE is in throttle response.
And who would want fast throttle response in a sportscar? Why, it
could make you spill your coffee...
____________________________________
;-)
I agree with pretty much everything he said about the Weber on the siamesed
port engine. Slight increase in top end power, often with attendant slight
loss down lower, depending on main venturi choice. In either case, you are
sure
to have to deal with the problem of initial tuning, as Webers are delivered
with jets, venturis, emulsion tubes etc. that suit an OEM car - normally
Fiat, Alfa etc., and are often far away from what is needed on an MG. Unless
you
have a very good Weber man on call, most people NEVER get the thing properly
tuned.
The accelerator pump aspect is probably a tad over-rated - an SU needn't
give much lag at all.
I think that the SU is a vastly underrated carb - it can produce excellent
results in racing or street use if you know what you are doing. The point is
that for 95% of applications, SUs are as good or better - and the downdraft
Weber is nothing but a cruel joke, but it sure extracts lots of dollars from
people intent on bragging rights who want to say they have a Weber - when
someone with one of these starts bragging about his 'Weber' I always say that
I
assume they mean a BBQ as the money would have been far better spent that
way....
I admit to being a bit surprised at his statement that the 1 1/2" SUs need
not be changed on even a fairly hot street engine - I have found that they
work well without significant loss of low end on engines that he'd use the
smaller carbs on. I guess you'd have to refer to actual dyno results to see
which
is the more correct view, but I won't argue with his findings - the guy seems
to have plenty of experience with street conversions and tuning.
Don't misunderstand me - I like Webers a lot. On an engine with separate
ports, properly tuned they can be an absolute delight. Getting them properly
tuned on something like my Lamborghini (6 - 40 DCOE) is more than a trivial
task, mind you. I also like them on race engines, and have used them both in
my
TVR (HRG head) and on my Twincam, but remember that in those applications I
don't really care at all about low speed driveability - as long as it offers
smooth power delivery between about 4000 RPM and red line (6500 on the TVR,
7800 on the Twincam) I am happy.
I guess I just found some straight talk on this subject refreshing - I have
seen so many people with MGs with thrashed engines, the rockers wobbling on
the worn shafts, the distributors on their last legs, the valve seats probably
looking like they were carved from lumps of coal, and do they want to do a
proper rebuild? No, they want to stick a Weber, or one of those stupid Mallory
distributors or some other bit of automotive flash on their lump because it
will not only (in their own minds, anyway) be a cure-all, but will also offer
bragging possibilities.
Bill
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