[Rovernet] P6B Pertronix conversion

[magnet at ican.net]

Just finished fitting a Pertronix conversion to my 1970 P6B, and I 
thought I'd pass along some observations for the benefit of any fellow 
P6B owners who might be considering such a conversion.

I had a number of reservations about going electronic -- solid state 
devices in cars are not always a joy forever, and there seemed to be 
some question as to whether the tach would operate correctly with the 
Pertronix ignition.  However, I decide to bite the bullet and try it 
out, as the 35D8 points system wasn't without its own problems.

I got the Pertronix kit (LU-181A) from Jegs High Performance in 
Delaware, Ohio.  It cost US $88.37, which I didn't think was a bad 
price, even allowing for the additional cost of shipping to Canada.  The 
kit includes a replacement distributor base plate, a rotatable mounting 
plate that connects to the vacuum capsule and carries the magnetic 
pick-up and amplifier module, a plastic collar (presumably containing 
eight magnets) that fits down over the distributor cam, a grommet for 
the hole in the side of the distributor, the Pertronix module itself, 
and a rather basic sheet of installation instructions.

It is quite possible to fit the conversion without removing the 
distributor from the car.  The first thing to do, after removing the 
distributor cap and rotor, is to unscrew and remove the hexagonal point 
gap adjustment screw (a 7mm wrench fits this).  Then remove the points, 
condenser, and triangular mounting plate.  Next, remove the vacuum 
capsule (2 screws on the outside of the distributor).  With this out of 
the way, you can remove the old base plate (3 screws).

The advance weights are now visible, and it is a good idea to see that 
they move freely and that the cam can turn a few degrees on its shaft.  
Lucas used to suggest removing the screw in the centre of the shaft and 
adding a couple of drops of oil occasionally.

Refit the vacuum capsule (an extendable magnet is very handy for 
retrieving the screws that fall down under the car).

Before fitting the new components, you need to remove the existing wire 
that went to the points, and it is moulded in unit with a plastic 
grommet.  I used a sharp chisel to get rid of it with one tap of a hammer.

You are now ready to fit the new base plate. I found that two of the 
three holes for the mounting screws had to be bored out before all three 
screws would line up.  (They do not mention this in the instructions.).  
Fit the rotatable plate to the base plate and insert it into the 
distributor housing, ensuring that the pin on the rotatable plate fits 
into the hole in the arm that goes to the vacuum capsule.  Refit the 
three screws that hold the base plate, with the braided wire from the 
Pertronix module under the head of one of the screws.  Put the grommet 
on the wires from the module and feed them out of the hole in the side 
of the distributor body.

Now, temporarily re-fit the rotor and measure how high the top of the 
rotor sits above the edge of the distributor housing.  I have found 
rotors differ in height-- even among genuine Lucas parts -- and there 
have been reports of the rotor sitting too high once the Pertronix 
collar is placed over the cam, to the point where it fouls the 
distributor cap.

Remove the rotor and fit the collar over the cam.  I found that the 
collar would slide only half way down on the cam, and I had to use a 
small, sharp chisel to remove a minute ridge of plastic from each of the 
eight faces inside the collar before the collar would seat properly.  
(The instructions did not mention this, either.)  Ensure that the collar 
is firmly seated on the cam.

Re-fit the rotor and re-measure its height.  It will be higher than 
before, and this may or may not cause a problem.  (Once more, the 
instructions are silent about this.)  To be safe, I ground a bit of 
plastic off the bottom of the rotor to bring it to a height just a  
trifle higher than it was originally.

That pretty well completes the mechanical part of the conversion.  The 
electrical connections are straightforward enough, the only slightly 
awkward bit is providing an ignition-switched  source of 12 volts to the 
Pertronix red wire.  I extended the red wire and ran it through the 
firewall.  If you open the driver's side glove locker, up and to the 
right of the steering column you will find a set of wires that connect 
the ignition switch (the plastic-covered wires) to the car's wiring (the 
fabric-covered wires).  The wires are joined by male and female Lucar 
(1/4-inch spade) connectors.  Take a tap off the white wire and connect 
it to the extended red lead from the Pertronix.  The black lead from the 
Pertronix goes to the coil's (-) terminal (the one that used to go to 
the points).

So after all this, how does it work?  It fired up on the first turn and 
the idle was notably smooth.  There are no problems with the 
tachometer.  I have not yet checked the timing, but a road test 
confirmed a significant improvement in high-RPM performance as well as a 
smoother, steadier idle.

As to reliability, only time will tell, although I haven't heard any 
Pertronix horror stories.  I put all the parts I took out in a plastic 
bag that I'll carry in the boot.   In an emergency, the distributor 
could be converted back to a straight electromechanical unit (although I 
would hate to do this by the side of the road!)

Cheers,

  -- Bill Daddis