A few weeks ago I mentioned that I was hoping to fit the early dizzy
with the vacuum advance to my 74.5 and I am pleased to report that this
project has been a huge success and I am very happy with the results.
After mucking with the thing for a while myself I sent the unit off to
Bob Sarama at lucasdistributors@yahoo.com. He refurbed the whole thing,
set it up on his Sun tester and sent it back looking like new.
I had asked Bob to set it up so I have some options with the
configuration and he has done that very nicely so I can configure for
41202 mode with a max of 38 degrees advance ( (10 mechanical + 9 vacuum)
* 2) or 41558 mode with a max of 42 degrees (12 + 9 * 2) of total
advance including the vacuum.
To date I have only tested it in 41202 mode with the vacuum advance, no
retard (I removed the retard and replaced it with the vernier adjusting
knob for fine adjustment) and with the static timing set to 12 degrees
BTDC.
The car runs beautifully with this dizzy and pulls strongly all through
the rev range with no hesitation or flat spots. I bought some rebuilt
carbs last year from Jeff Palya (who also did a superb job) and had them
built with just the vacuum advance port, no retard so I have minimized
the opportunity for vacuum leaks. I found that cold starting is easier
and I need to use much less choke but I have no idea if I could
attribute that to this dizzy.
I did have to rotate the unit a little to get the vacuum advance
connection and the tach connection in the right orientation. Thanks to
the help from Bob and this list I managed that quite easily and in fact
got very good at it after many different attempts to get the right
position and get the oil pump drive shaft in the right position to
engage.
I will try the 41558 mode when I get the time and report back on how
that goes but the car runs so well I have not been highly motivated to
change anything.
Stan
<snip>
Shannon---24 deg. of centrifugal advance is about the right amount. By
setting the idle timing, (where no advance should be taking place) to 10
deg., you'll then have 34 deg. when the timing is all-in.
I'm not sure what controls maximum timing on the Mallory. If it's a stop
post like on the Lucas, then a change of advance springs may not alter
the total.
If you feel you want more total timing, and can get away with it, you
can set the initial timing up to 12 or 14 deg.
Vance is correct about checking the operation of the retard capsules on
the Lucas. I always recommend starting the timing process with this
feature DISconnected, and then see what you get with it reconnected. A
moot point with your new setup.
Dick
</snip>
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