Hi,
When I bought our 78 (back in 85), I found that the PO had "removed" all
of the emissions equipment (with a hacksaw, apparently) and had also made
a pretty miserable mess of the original carb. Being short of the cash to
restore all of the original, I went with a Moss-supplied Weber downdraft.
Which worked well.
A couple of years ago, the local region was about to be placed under more
strick smog controls. It was pretty clear that the MG woulnd't have a
chance: One passing glance under the hood revealed the total lack of
anyting like smog equipment. At about that time, the Moss rag (can't
remember the name of their publication) came out with a two-part series on
smogging.
Reading the articles carefully, we designed the equipment. We needed an
air pump, and found an original; we also needed the air distribution pipes
(the ones that go to the head), so we bought new. For the rest, it's
mostly off-brand, with some hardware-store: The ERG value itself is a
Pep-Boys generic, mounted to the right of the Weber and fed by steel
piping (big-truck brake lines) from exhaust manifold to intake; the Weber
has an EGR control take-off. For the valve that controls fresh air from
pump to manifold, we bought one for an older Datsun and designed feed
pipes to the intake manifold.
The final (and seemly most difficult) problem was to design a warm-air
carb preheat. We abandoned entirely the idea of an electrical device, as
mounted originally between carb and intake manifold. But we did come up
with an exhaust-manifold-heat system. The Weber from Moss came with a K&N
filter, open on all sides. We fiddled with several different ways of
trying to enclose the whole thing and feed it with air. It was all pretty
ugly and unsuccessful. Finally, late one night, I lay in bed thinking
about the problem and spotted on the nightstand one of those larger cookie
cans, the flat kind with the lid. A perfect enclosure. Next morning, we
dug through the cookie-can collection and found theperfect size. In the
bottom, we cut out to fit exactly between the Weber's intake and the K&N,
and drilled two holes in the top to fit the K&N's screws. In the side of
the can, we built a port and used generic hot-air feed pipe to go to the
exhaust manifold. At the manifold itself, we found an older Mustang
cowling that, with some conditioning, fit perfectly over the front (left
of Weber) exhaust-manifold pipe. The warm-cold diverter is original
equipment and fits the Mustang cowling.
The car has no cat converter. So does it work? In the several months
before the area officially instituted smog testing (and before the whole
program was called off!), the facility would test cars for free just to
see if they would pass when 'real' testing began. The MG passed with
flying colors, coming in well below specs on all regulated gasses.
Performance? Well, the system probably didn't help matters, that's for
sure. On the other hand, Webers are pretty good carbs and can be tuned to
the Nth. Bottom line: Performance isn't that bad at all, and we've got a
'smogged' MG.
later,
Lynn
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