1933 L2 MAGNA REBUILD
One task which I managed to complete
before the car was trailered down to
Shaftesbury (see photo of the car which was
taken just after it had been unloaded from
the trailer and pushed into the premises of
Bob and Charles Jones) was the fitting of the
dashboard. This is quite a tricky job and
entailed the use of a hole saw to fit the
instruments and the manufacture of brackets
to secure them behind the dashboard.
The result can be seen in the above photo.
Well I guess that’s about it for now until I
get the car back with a rebuilt engine,
gearbox and supercharger fitted. However,
to maintain my essential diet of MMM
mechanical engineering I’ve been ‘playing’
with the manifolding arrangements on my J2
and the following is an account of the
problem and the solution employed.
Breathing difficulties in a J
Before Barry Foster installed a Shorrock 75 supercharger in my J2 the car would always run out of breath on the hills. It would be
a case of gradually losing revs, changing down through the gears, and eventually grinding up in second gear. The supercharger,
blowing at about six to eight pounds per square inch, completely transformed the car. It gave it more power but, more importantly,
more torque. Most hills can be driven up in top and it will keep up with modern traffic or six-cylinder MMM MGs pretty well.
This benefit, however, came at a cost. The original manifold delivered pressurised petrol, air and oil mixture to cylinder number one
first. On the open road, when the car was thoroughly warmed up, this was not a problem. But in the town, in heavy traffic, number
one plug had a tendency to become fouled. As I live in the middle of a large city, the first 15 minutes of any journey are always in
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heavy traffic. I tried all sorts of different combinations of plugs-NGK B6HS, B7HS, a mixture of the two and even B5HS following a
conversation with NGK. The best compromise was the long reach BP6HS, but the number one plug still had a tendency to foul up
with all the subsequent banging and misfires. The problem was solved by ensuring a better mixture delivery by altering the inlet
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manifold so that the gases were more homogeneous. I enclose photographs of the original manifold and the modified one. The latter
was made by a friend from 1
1
/
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2-inch pipe by cutting and TIG welding. It seems to be working well and I’m back to the B7HS plugs
at the moment. The car seems to be much more tractable and at least all the plugs are the same colour now!
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Original Manifolding Revised Manifolding
34 Safety Fast! NOVEMBER 2008
www.mgcc.co.uk
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