>From Dan's reference at _http://www.studdsey.fsnet.co.uk/mgbtunings.htm_
(http://www.studdsey.fsnet.co.uk/mgbtunings.htm) - thanks for that, Dan -
this
guy obviously has a lot of experience.
For those who want to use a Weber, he says:
"The use of the Weber DCOE 45 carburetor on street MGBs came about as a
result of their use on the factory team's racers. This fact, of course,
produced
a "monkey see, monkey do" mentality amongst those seeking more power for
their street MGBs. Why did the factory race team choose the Weber over the
tried-and-true SUs? It has to do with the design differences between the two.
The SU is a Variable Venturi type, which makes for smooth although slightly
slow throttle response and excellent fuel economy. The Weber DCOE 45, on the
other hand, is a Fixed Venturi type. It has the advantage of having an
injector pump to shoot raw gasoline into the venturi when the throttle opens
rapidly
and thus makes for very fast throttle response. This was a definite
advantage on the race track, so that's part of the reason why the factory race
team
chose it over the SU. Remember that on a race track, smoothness and economy
must be subordinate to responsiveness, as its responsiveness that makes
aggressive driving possible. Victory is what counts on the track, and nothing
else will substitute.
This fast throttle response produces the illusion of more power and so
purchasers of this unit tend to experience what Psychologists call the "Halo
Effect": they've paid out the big money, sweated the installation, spent more
money to convert their ignition system to a centrifugal advance distributor
(Weber carburetors don't have provision for a vacuum takeoff for working with
vacuum advance ignition systems: read the fine print!) and so they're already
predisposed to feel the power increase even before they drive. When the quick
throttle response creates the illusion of more power, they're like religious
converts! In reality, all other factors being equal, there is no worthwhile
difference between them in terms of power output on the dynamometer readouts
unless a radical camshaft is being used"
And on another of my favourites:
"The Weber downdraft DGV 32/36 makes the engine look as though it was
pirated from a Russian tractor. Its usually included adapter manifold has the
flow
characteristics of a bathtub with a hole in each side."
He also addresses another of my pet peeves - what a bad idea it is to use
Lotus pistons for big bore engines, but he says is much better than I would.
I have rarely seen so much good sense about the B series engine in one place
- anyone seriously interested in the engine should take the time to read
this carefully!
Thanks again, Don.
Bill
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