This is the last post tonight I promise! Between being on the road and
living through our annual budget process at work, I have not been able to
spend much time with the list and, once I started, I just couldn't stop!
As I stated in the last post, SU's, as used on our beloved MG's have no way
to compensate for engine loade. For a given air flow, they mix the same
amount of fuel whether you are running no load at 3k or lugging at 1k rpm.
I have been looking at the HD6 carbs that came with a pile of Jaguar parts
that may or may not add up to a car. The D stands for diaphram. Before
anyone chips in with some dirty remark (where is Bob Allen anyway?) the
diaphram is part of a vacuum chamber attached to the jet. Under high
vacuum, the jet is pulled up and leans the mixture. This should allow for
more efficient cruising. Has anyone done a back to back test with an HD
carb and a diaphram-less counterpart?
Now I am not goig to mount a pair of HD6's on the A. They look like the
added complexity would cost more in headache than I would save in fuel.
For instance, since the diaphram controls the jet, you can't pull it down
for cold start enrichment. For this the Jag's use a "starting carb" which
is a solenoid controled, calibrated fuel leak into the manifold. A more
elegant solution could have been found, don't you think?
Regards,
Bill Eastman
61 MGA with H4's- why mess with a winner?
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