When it came time to install our D.U.I. distributor
we naturally weren't going to use our existing dirty
set of wires. Poor plug wires can misfire and kill
any benefits of the high voltage spark output. Furthermore,
we needed a rugged set of wires that would hold up
next to the 460's big header tubes. As a result, we
went with Performance Distributor's own LiveWires.
The hefty 10mm spiral wound wires have a very low
resistance of 300-350 ohms. A nice plus is the integral
heat-resistant sleeving which will prevent burning
on headers. With this much juice getting to the spark
plug you can increase the gap to 0.055" to get
a nice big spark to light off the cylinder charge.
This flat-sided thermostat
housing may be neccesary to clear the large distributor.
The larger distributor
body may cause clearance issues with wide diameter
drop-base style air cleaners.
On the dyno we placed the
D.U.I. up against a new Motorcraft™ dual
point unit, to see the difference versus a stock
Installing the D.U.I. distributor is straight forward.
On some 460 engines it may require the installation
of an offset thermostat housing, available from Performance
Distributors. The cast-iron housing is machined flat
on the side facing the distributor in order to provide
clearance for the larger diameter cap and housing body.
We also experienced slight intereference between the
cap and our drop-base air cleaner, required due to the
tall plenum height of our Weiand Stealth manifold. For
the dyno testing we ran without an air cleaner, however
for the road we will use an offset base or a shorter
As mentioned previously, the big advantage to the D.U.I.
is the wiring simplicity. We took the 12V positive lead
which once ran to the positive side of the stock coil
and simply attached the supplied female terminal connector
to the D.U.I. unit. We also took advantage of the D.U.I.s
tach output terminal and wired up our Autometer tachometer
for accurate rpm monitoring.
During the dyno testing of our Streetwise 460 motor
we made initial baseline pulls using a new Motocraft™
dual-point distributor and coil. To emphasize "as
delivered" conditions we made no changes to the
advance rate or curve on the stock distributor. We installed
the stock distributor with 14 degrees initial advance
and checked the total advance on the stock distributor
to be 34 degrees, coming in at 5000 rpm. The slow advance
rate of the points distributor showed its' weakness
in both street driving as well as dyno testing. Throttle
response was rougher and the engine was audibly slower
in reving from 2500 rpm to 5500 rpm on the chassis dyno.
Results show power down all across the rpm range (see
chart below.) Perhaps more telling is the A/F ratio
which is noticably richer, indicating incomplete burn
in the cylinder.
While the engine cooled from its' baseline runs we dropped
in the D.U.I. unit and reset initial timing to 14 degrees.
We checked total advance and found it to be 36 degress
at 3000 rpm, exactly what the paperwork accompanying
the distributor indicated. Furthermore, unlike the points
unit, the timing light showed dead steady timing marks
at 3000 rpm. The engine fired right up and a few blips
of the throttle indicated a snappier, crisper sounding
460. The motor responded to the D.U.I.'s advance curve
and fatter spark with 25 horsepower at about every rpm
point from 3500 to our self-imposed redline of 5500
rpm. Torque was up equally as well. A review of the
air-fuel ratios reveals a leaner mixture, indicating
more complete burn in the cylinders. The average air-fuel
ratio at wide open throttle went from 12.3:1 to 12.9:1.
The results clearly show that whether you are building
a motor back to stock, or for performance, it pays to
upgrade from the stock distributor. Not only is there
power which can be unleased, but we're adding in reliability
as well. The D.U.I. gets our vote for a custom curved
high-output ignition system that installs in minutes
without complicated or messy wiring. We've got high
hopes that this system will stave off Murphy's Law for
a while - at least when it comes to firing up our 460.