Well, I have seen one brave fellow who offered up an opinion on why
distributors have two sizes of springs. His was the explanation that I
have heard many times before- that the light spring controls the advance
at low rpm while the heavy spring kicks in at high rpm. Until a few
days ago, I too subscribed to this belief. However, after some serious
reflection time contemplating the insides of my spare dizzy, I think
that there is a more likely explanation.
If you play with your distributor on the bench, you will notice that
there is s fair bit of slop in the mechanical advance system- the pegs
are not a real tight fit in the advance weight grooves. So if both
weights flew out at exactly the same time, this slop could allow some
wandering of the timing or, at the least, some lag in timing change when
the engine switches from acceleration to deceleration or vice versa. By
allowing one of the weights to always lead the other, this slop is
removed and the timing curve becomes crisper.
Which brings me to a personal dilemma. When I had my dizzy apart last
year, I noticed that one of the springs was a loose fit on its pins when
stationary. I assumed that this was a bad thing caused by the spring
stretching. Now I am not so sure and I am concerned that my shortening
of this spring could have introduced some timing instability at low
speeds. This could help explain the slightly lumpy idle the A has
although the new street performance cam may also contribute. How about
the rest of you? Has anyone else noticed one loose spring in their
dizzy?
After seeing very few MG's this year, I saw a red TD in Champlain and a
very dark red (almost maroon) A in Edina in the past two weeks. Anyone
I know?
And for those of you who may have been going home on West 694 last night
and saw a red MGA with a bent bonnet sitting dead in the middle lane, I
just want to say that the traffic jam was not my fault! It started when
a 56 Chevy that was two cars in front of me died. I stopped and offered
help. We pushed his car to the shoulder then I went back to the middle
lane to retrieve the A. I then tried to jump the Chevy and get it
started. It turned over like mad but no fire. The Chevy owner had a
cell phone so I wished him luck and departed. At no time did the MGA
refuse to run. I half expected to see "Major traffic jam caused by
unreliable British car" in the paper this morning but, to my relief,
there was no major media coverage. One person at work has already come
up to me this morning with some lame comment on British cars having had
his afternoon commute spoiled. You can be sure that I set the record
straight.
Regards,
Bill Eastman
61 MGA getting much more exercise again now the heat wave has broken.
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