Adrian Jones wrote:
> Anyhoo, the 1500 makes the 1275 a total road rocket in comparison.
Just off the top, I would suspect a problem there.
The pollution control devices essentially counteracted the
gains from the increased displacement of the 1500.
Unlike the MGB, where the engine never changed so the
power just kept going down, Midget power tended to stay
about the same when expressed in similar units.
> In an attempt to make the 1500 more responsive, last week I removed the air
> pump belt and reset the timing from 2ATDC to 12 BTDC.
The timing at 2 degrees ATDC is really not that far from
an earlier midget timed at something like 10 degrees BTDC. This
is because these timings are done at idle, when the 1500s
vacuum retard is fully in operation.
In other words, at idle, your timing is retarded by the
vacuum retard to 2 after, but it's "really" a few degrees
before zero. Once you come off idle, the vacuum retard
stops doing anything, and the timing goes back to what older
Midget owners would call normal.
Check your cars dynamically against each other, and if
you like, set the 1500 to the same timings as the 1275 at
2500rpm or similar. At idle, you'll probably find the 1500
isn't very far off the 2 deg ATDC the factory suggests.
> The drive seems a little more smoother than Binky
> but that is a combination of many things, I suppose.
The retarded timing helps smoothness. Actually a few
things help smoothness, which was another goal from BL
with all the engine changes and detuning.
The market was changing, and the Spridgets were losing
head-to-head test drive comparisions because they seemed
so much rawer and less well behaved than competitors. To
people on this list, that may seem like a feature, but
it was felt it hurt sales at the time. I guess it makes sense,
most people expect new cars to be magically smooth and
well behaved.
> Of course, Binky has twin SU's and Doe-Doe has a single
> Z-S - is that the problem?
It helps, but you still shouldn't be so far behind. The
1500 with limiting carbs should be about even with the
1275 with better flowing carbs.
The 1500s torque tends to be lower in the RPM band with
a single carb limiting high flow, but it's there. I guess
it's a tradeoff between the thrilling high RPM torque and
the more useful around-town-without-attracting-even-looks
from-revving power.
...of course, throw in some SUs and it's a new machine.
--
Trevor Boicey
Ottawa, Canada
tboicey@brit.ca
http://www.brit.ca/~tboicey/
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