Hi David,
For your survey:
Car _ BN2
Distributor _ DM2 converted to 25D advance mechanism
1. Which rotor are you using that failed? _ No failure, using 40 year old
Echlin rotor.
One failure with a Lucas rotor. See comment below,
2. What are you using for a coil? _ Pertronix
3. What distributor cap brand? _ 30 year old Lucas
4. What plug wires? _ Stranded metal core
5. What style ignition _ Pertronix
Comments _
A- Plug gaps set at 0.028", faultless ignition for many years.
B- Tried a new Lucas rotor, which shorted. Removed the rivet & contact. Warmed
the rotor &
filled the contact arm recess & any possible voids/cracks with warm slow set
JB Weld,
replaced the contact arm, let LB Weld set. Warming the rotor & epoxy would let
the JB Weld
be drawn in to any microscopic cracks in the insulation as it cooled. No rivet
which "may"
have caused a tiny crack in the rotor "if" the rivet was originally over set.
Ran this
rotor for about 6 months, no failure, replaced the old Echlin rotor, & keep the
repaired
Lucas as a spare.
Personal opinion -
A- Wide plug gaps with their higher required firing voltages, reduce the
somewhat limited
insulation capabilities of the original design rotors & the somewhat narrow
distributor
cap contact spacings between plug wire terminals. The newer design higher
voltage caps &
rotors have considerably wider cap terminal spacing & better rotor to shaft
insulation
than the old Lucas design.
The relatively wide rotor contact nose reduces the plug to plug rotor cap
contact
clearances & "could" contribute to cross firing if wide plug gaps are used.
B- The "new" Lucas rotor was apparently defective but responded to repair
efforts.
In summary - To me, the "advantage" of the Pertronix is increased reliability &
reduced
maintenance. Although it is capable of higher voltages & could fire wider plug
gaps, using
this advantage may lead to other problems as outlined above.
Note: I have measured a number of rotor/cap combinations. The rotor tip to cap
contact
spacing & the required voltage to jump this space can vary considerably between
various
cap/rotor combinations. In some cases, this gap is considerably wider than the
plug gaps.
Sorry if I bored anyone with this lengthy reply.
Regards,
Dave Russell
BN2
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