Todd:
You remembered correctly. The 45D is technically superior to the 25D
design, especially when fitted with points.
In general the cap and rotor re-design makes the unit less prone to
carbon tracking making the unit more suitable for electronic ignition
usage.
The point sets and operating cam were upgraded giving longer life and
better accuracy without the need for high spring pressure.
There were two different point sets available in the 45D unit. The
earlier design had a red lifter block and was found originally in the
Fed spec. 1975 only application. Later during the 80s the red point set
was superseded by the blue self wiping points. These point sets are not
interchangeable. Also if you are fitting a Pertronix unit, you do have
to get the correct one to fit the installed point plate.
If the unit you received had no numbers on it, then it is probably the
reproduction of the original Lucas 41427 unit. The repro units use the
later blue type point sets and have the correct centrifugal and vacuum
advances for the 1962-67 MGB application. It turns out this unit also
works well with manifold vacuum although I would not have believed it
until prompted to give it a try by Carl Heideman.
Kelvin.
-----Original Message-----
From: owner-mgs@autox.team.net [mailto:owner-mgs@autox.team.net] On
Behalf Of Todd Mullins
Sent: Saturday, July 15, 2006 7:38 AM
To: mgs@autox.team.net
Subject: 25D4 vs. 45D4
Hi all,
I've been slowly gathering parts for my '74 MGB reassembly. My
emphasis is on optimizing functionality and performance, rather than
a historically correct restoration.
Years ago, I remember reading that the Lucas 45D4 distributor is
technically superior to the 25D4, as originally fitted to my car. I
found a brand-new Euro-spec 45D4 on eBay, and promptly snatched it
up. After it arrived, I naturally felt the need to justify the
purchase by searching the web for that information that had prompted
my purchase in the first place, but so far I've come up empty.
So I put it to you: Is the points-equipped 45D4 superior to the
points-equipped 25D4? I know that electronic ignition levels the
playing field here (and I'll probably buy a Pertronix for the 45D4),
but I'm interested in your opinions of the intrinsic strengths and
weaknesses of the two distributors in their original form.
As always, thanks for all of your informed opinions!
-todd
'74 MGB Tourer in a jillion pieces
'80 Kawasaki KZ440 LTD daily driver
'84 Bertone X1/9 wife's daily driver
'87 VW Cabriolet on loan to my sister since Katrina
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