[Rovernet] P6B Pertronix conversion

Thu Jul 28 13:18:13 EDT 2016

Hi Peter,

Thanks for that!

Cheers,

  -- Bill

On 28-Jul-16 12:18 PM, peter king via Rovernet wrote:
> Hi Bill,
>
> I’ve had a Pertronix ignition in my 3500s for a number of years with no problems. I do want to alert you to the need to protect the wires inside the distributor from chafing, as I neglected to do so on the one in my P5, resulting in the eventual wearing away of the insulation and ultimately shorting out.
>
> Peter
>
>
>
>
>> On Jul 27, 2016, at 10:49 PM, Steve Manwell via Rovernet<rovernet at rovernet.org>  wrote:
>>
>> Bill,
>>
>> Thanks for doing this extensive write up.  I looked into the issue of too little clearance between the rotor and the cap when Danny Archer came across the problem.  It turns out that there are two (at least) Lucas rotors, one a little taller than the other. With the Pertronix magnet ring in place, the taller rotor (p/n 54422044) jams against the center contact of the cap, while the 1/16" shorter one (p/n 54424762) rotates freely.  These are original Lucas rotors with the numbers molded on them, and checked against Lucas caps.
>>
>> Most aftermarket rotors appear to be based on the taller design, whereas Pertronix must have made their components compatible the shorter, more obscure rotor design.
>>
>> Based on my experience with the P4 during Rove America this year, I would avoid rotors that have the conductor riveted to the body, and use rotors that have the conductor molded into the plastic. Both of the original V8 rotors noted above are the molded type.
>>
>> Steve
>>
>>
>> On 7/27/2016 7:36 PM, magnet--- via Rovernet wrote:
>>> 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
>>>
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>>>
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