Like many of you, there was a time when my own Lucas ignition system
became suspect. Cap terminals were being eroded, and I could hear that
arcing was going on under the cap. Both were solved with one move, tho
it took months to figure it out.
This is the short story:
After moving the damper pulley to where the timing was at 12 deg. BTDC
with #1 firing, I saw that the rotor was almost as close to #4 terminal
as it was to #1.
Points were just opening.
The terminals are on one inch centers and the (typical) rotor is .625
wide at the wiping end.
The spark had to jump a distance to get to the right (#1) terminal. I
believe this caused the erosion of the terminal tips. More later on
this.
Since spark will go to the path of least resistance, it would sometimes
jump to the "wrong" terminal. Misfire (A timing light on #4 plug wire
was somemes being picked up as #1) Wow!
Advancing the timing thru distributor rotation helped a little, but sure
wasn't the answer.
My solution:
What got the spark event to occur when the center of the rotor was close
to the center of the cap terminals, was in the moving of the points
plate, CCW. Simply done by shortening the link to the vacuum retard.
This pulled the timing to "retard". Then advancing the timing with the
distributor body got the timing back again.
I no longer have to run with a rotor tip that's cut off at the back end.
The (Lucas) cap with aluminum parts now last for....who knows? No
erosion now for tens of thousands of miles.
I have seen other TRs that fire off the leading tip of the rotor. Their
caps were showing the eroding as well. Even the brass ones.
In another post I'll bore you with Lucas timing variations, and reducing
them.
Dick Taylor
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