Hmm.. Well I had no probs with my Colortune, found it very easy to work with
and the result was much better than before I used it. Much smoother idle and
better power too. It is harder to start when cold tho, but this is CORRECT.
MG's are supposed to be like this. You are not supposed to be able to start
a cold MG (with no auto-choke) and drive away cleanly without using the
choke. I would suggest
there is something else not quite right with the car. How about Dwell and
Valve clearance? Dwell is critical to good idle. What about the dist.
itself? Is the timing jumping around under the light? Could be a worn
distributor. Is there any sideways play in the shaft? All of those things
will show up in fluctuations in the color of the mixture. It mentions all of
those items in the Colortune instructions btw.
The first time I used the Colortune everything worked
perfectly, then the old carbs decided to give up the ghost and I couldn't
tune it to save my life. So back to be rebuilt, resynced the carbs, set to
starting position and tuned each carb independantly. I had a perfect result
in less than 10 minutes. The carbs are supposed to be synched for airflow,
then tuned for mixture independantly. I'll be doing it again in about a
weeks time when I get my cyl. head back from the machinist. The 12 flats
down on the mixture nut is purely a _starting_ position. The carbs need to
be tuned from that position to match the requirements of your motor. If they
don't need adjusting and mixture is already correct then you are very lucky!
Idle quality, plug cuts, colortune, temp etc etc will guide you there. Also,
after
speaking to Bill Bressington at sumidel a few weeks back, he mentions the
correct oil
to put in the dampers is 20/50W. The heavier oil helps to slightly enrichen
the mixture
on initial acceleration, he doesn't recommend any of the lighter
oils. So std MGB engine oil is fine.
I really suggest a copy of Lawrie's SU Video available via Moss and a copy
of the SU Manual by Haynes. Both of these are excellent references.
Lawrie - feel like a dissertation on correct usage of the colortune?? <G>
Cheers,
Neil.
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