Rick,
Having been through most of the options you are considering, I
can offer some of my own experience. These are my personal
observations, and are not engraved in stone. Others will have
a different view, and experience. It depends on what you are
willing to trade.
Using Edlebrock Performer (not RPM) manifolds on both a 289
Mustang, and a 302 Mustang II, both with 600 CFM Edelbrock
carbs gave very smooth performance. The Edelbrock is NOT just
a polished Carter, but was design modified by Weber. Even
some of the basic Carter design features are better than the
original Holleys. No power valve to blow out, and only one
gasket, which is above the fuel level, so doesn't get wet and
leak. Tuning it is different, with springs and needles,
rather than jets and valves, and springs, power valves, and
pumps and cams. Different than what you may be used to, but
easy when you learn. Even rated at 600 CFM (and they DO make
a 500 CFM), it ran smoothly under all conditions and did not
show flat spots or bog during acceleration. But, the air
velocity was controlled by the engine flow demand, not the
throttle pedal, so the secondaries didn't come in as the
mechanical Holley double pumpers do, and slow down the air
velocity, loosing good fuel atomization, and dump too much
charge into the system before it can handle it.
Now the vacuum secondary Holleys are better at volume rate
control, after you've got the diaphragm spring correct.
There are arguments that say the volumetric efficiency of a
260-360 CID engine simply requires nowhere near 600 CFM. This
is correct, however, don't believe the carb rating is all that
correct, though.
On my 260, the Holley LAT 465 CFM Holley is very smooth, has
no sogs, or bogs, and behaves nicely under all conditions
except those in a long turn in the wrong direction, where the
fuel piles up on one side. Need a center-hung bowl for this.
(I believe you can buy them and bolt them on, though.) The
Edelbrock Air/Fuel ratio meter shows dead-on mixture ratio
under all driving conditions, and validates Dr. Palmer's
statement that today's lousy gas requires richer mixtures.
This carb gives good fuel mileage around town too, and gas was
not cheap the last time I was in England. (Just added picture
of Blenheim Palace on the just finished Rootes meet on the
Events page.) It would be my choice, or the 500 CFM Edelbrock,
for a moderate 260 or 289 and the desire for derivability as
well as power. With a hot 302, I'd probably go with the 600
and vacuum secondaries. No larger. That LAT 715 doesn't fit,
and doesn't behave nicely except on the race course at WOT on
the really hot engine.
If you've got a rad 289-302, then a 600 will probably work for
you, as it has for may others, depending on whether you choose
the vacuum (preferred by me) or mechanical secondaries, and
your usage.
Having driven around England, Scotland and Wales (except
London!!), I kind-of know the roads you deal with, and unless
you do club racing, you are unlikely to need the mechanical
secondaries, and WOT driving. Nor, I believe, will you be
going fast enough around normal curves and traffic circles to
worry about a center-hung float bowl.
The choice of Holley's vs Edelbrock's is more likely to depend
on whether your English Mechanics have ever messed with them.
Wouldn't want to train someone on needles and springs, even
though SU's and Strombergs use needles. Ought to check that
out.
Don't worry about hearing a lot of different opinions. This
argument has been going on about as long as the Ford and Chevy
crowd has been at it, and no one has changed their mind there,
either.
BTDT.
--
Steve Laifman < Find out what is most >
B9472289 < important in your life >
< and don't let it get away!>
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