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Re: Best Carbs for MG??? What about the manifold?

To: "Lawrie Alexander" <>, <>
Subject: Re: Best Carbs for MG??? What about the manifold?
From: "Neil Cotty" <>
Date: Fri, 28 Aug 1998 01:22:20 +1000

Can we talk about inlet manifolds?! :)

As SU manifolds are virtually straight shot into the siamese ports of the
std B head, whereas a single Weber uses a bent manifold (long and short),
what _tangible_ impact does this have on performance (airflow), both economy
and power? Anything at all?

If a Weber was choked to the same max. size as an SU what difference would
there be? Would the bent manifold make it's impact felt in some way? There
is no balance pipe (is there?), therefore I would *presume* that idle would
be affected - ? I ask because I don't want to go to a single Weber (racing)
because of the airflow issue, I realise Webers are more responsive, flow
better (not inc. manifold) no piston etc, acceleration like an on/off
switch - but I have read and heard that the bent manifold seriously
interrupts the airflow - to the extent of making the better flowing Weber
somewhat redundant on a std MGB head (but great on any 8 port head with dual
webers).. A good example is a couple of local racers who are line ball with
each other, one runs a 45 Weber, the other 1 3/4" SU's.. They choose only on
personal preference, looks, setup etc and both agree that the differences
are subtle, the SU's providing slightly more torque, the Weber slightly more
power. Obviously length of the manifold alters this as well.

On a std car, there is no way I'd buy a Weber. Simply because SU's are
easier to maintain and setup for an amateur at home, only thing you can't do
yourself (After 2 hrs watching Lawries rebuild video :) is rebush the
bodies. They are also the correct Carb for an MG. I even think a single DCOE
looks naff on that huge inlet manifold (oO.. in my opinion - nomex donned
<G>) compared to a couple of SU's.. But I have to admit that two DCOE's on a
XFlow head look *seriously* excellent... <G> Drooolll..

If you don't believe me that SU's look good - take a look at this pic of
dual HS6 carbs on a Vintage Racer:

Flame suit donned, filtering enabled, bunker readied.... <G>


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