PROBLEM:
Good luck finding ANY of the 'correct' springs for your
distributor. BTDT. Lucas never released any of the
details of the spring 'specs' so the only way to really
get a good spring by itself is to go to a manufacturer's
catalog and order the specifics of the spring.
The problem is you have no idea what those specs
(as new) should be.
Many of the 'NOS' dists. you'll find out there are newer
units that replace the older original variations that have been
produced over the years. (yes there are plenty of original
nos units still floating around out there on peoples
dusty shelves etc.)
TESTS:
I've run experiments, mixing and matching 10+ distributors
worth of weights and springs and vac adv. units
to test the various effects on various LBC engines. I've filed
notches, and bushed posts...... to let the dists. further advance
or limit adv. as desired.
All in all I believe the variation of springs avail. is greater
do to aging and wear than the variations of the original springs
as manufactured for use in new dists. of the day.
RESULTS:
YMMV ... this worked for me anyway.... what I've found....
Usually the lighter of the two springs is worn the most.
This combined with a worn weight pivots and weights allows
advance to start at a lower RPM. This has most of us, setting
idle timing incorrectly because it's already advancing at an idle.
The timing comes in sooner but the curve is now stretched
as the larger spring, usually, correctly balances it's weight
for the upper rpm range.
Matching a dist advance curve to the cam and firing timing,
is a rough and slow 'trial and error' adventure.
But well worth it if you want to understand how it effects
everything through out the rev range.
Good luck.
Paul Tegler ptegler@cablespeed.com www.teglerizer.com
----- Original Message -----
From: <ValveCurtain@aol.com>
To: <mgs@autox.team.net>
Sent: Tuesday, December 19, 2000 9:22 AM
Subject: 25D4 advance springs
Hi Gang,
I seem to remember a thread about this so forgive
me if I'm draging out old laundry. The 25D4 distributor
in my '70 B-GT has two different sized springs on the
advance weights. One is stiff, presumably to set the
advance at the highest RPM and the other is quite small,
again presumably to set the advance on the slow end
of the rpm spectrum. Yet, when I go to the Moss or
VB catalogs, they list only one spring type for both
sides.
What are your observations? My E-type used the
same distributor, in a 6-cyl varient, and had equel
sized springs; both of which were less-beefy than the
larger spring in the 25D4.
Rick
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