> I read a bit on replacement and the 45D is being used for the
> 25D's now
> from what I could tell.
>
> How does the 45D compare to the other options?
>
> The Mallory dual point looks interesting, and I have seen others use
> it.
Andrew:
The 45D design was an improvement over the 25D. Lucas made many
modifications to improve reliability, and longevity and to reduce shorting
problems with high energy systems. Folks in the US get a warped view, as
nearly all 45D distributors on original cars were OPUS or CEI electronic
units. European cars used two points type versions of the 45D for many
years.
The replacement 45D distributor for 63-71 MGB Lucas 41427 (Moss
143-110) is IMNSHO the best unit to install on a street MGB using HS type
carbs (ported vacuum), end of story. The centrifugal and vacuum advance are
both correct. The cap and rotor design have increased clearance to reduce
arcing and the cam and points are designed for longer life and more accurate
operation. For lower maintenance a Pertronix unit can be fitted, and the
original points carried in case of failure.
Hey, did you know that spell checker wants to convert "Pertronix" to
"Patronize" Hmmmm. Maybe there is some deep significance there. Possibly
just the fact that some posts last week made me paranoid about spelling.
A couple of posters have noted correctly that the Pertronix unit is
more sensitive to shaft movement than the Crane/Allison optical unit, so if
you are considering a conversion because of a worn shaft the Crane would be
a better bet.
I would add that there have been a number of complaints in the
racing fraternity of DM2 and 25D cap and rotor shorting when using high
output systems switched by electronic ignition. A number of vintage race
preparation companies are switching back to points, as they are more
dependable in their customer's cars. This is not related to the quality
control problems that popped up a while ago with DRB101 rotor cracking,
which seems to be fixed now.
Please note, these are also the same folks who are having suspension
and drivetrain failures from increasing power output and tire loading way
beyond the original designs of the vehicles.
Warning: Rant mode on.
I'm not a fan of the Mallory. Aesthetically it hits me the same way
that a Weber DGV does. I want my car to look like an MG, not a Pinto*.
(it's ok, I just bought a new Nomex race suit). I want my cars to have
little esoteric fiddly bits on them, not big, lumpy easy to work on stuff.
The same reason I can't stomach coarse threaded fasteners, probably why I
still don't own a Harley.
*Note. This from someone building a MGB V8, maybe I should join hypocrites
anon.
All the best.
Kelvin.
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