Distributor Rotor Shorting

[Johnski]

I have had a number of distributor rotors shorting out in as little as 400 miles. I was told that the combination of the petronix electronic ignition and high voltage coil I am running were doing it. The solution suggested was use a special rotor from British Car Specialists or go back to points / lower voltage coil. Has anyone else had a similar problem and solved this?

 

[Dave Russell]

It's not only cars equipped with Pertronix & such ignitions. There have been many reports of "lucas" branded rotors, actually made in China or India, or somewhere, failing.

Different people have found different solutions. I personally am using a 40 year old USA made rotor that shows no signs of failing. I don't plan on ever changing it.

The problem with the recent Lucas rotors is thought by some people to be caused by over crimping the rivet which holds the brass arm to the insulator. This causes a microscopic crack in the insulator & a short path to ground at the distributor shaft. The factory may or may not have corrected the problem. Either way, there are likely to be hundreds of defective rotors still in dealers stocks. The old rotor that I am using has no rivet to start with.

I removed the rivet from a recently purchased Lucas rotor, warmed the insulator, & seated the arm in epoxy. Ran it on the car for about 500 miles with no problem, & keep it as a hopefully reliable spare. The thinking was that the epoxy would fill any small crack & there would be no rivet to worry about.

Someone may have found a source for good rotors, but I'm not sure where.
D
Edit: A mistake that sometimes happens is that someone gets a shorter four cylinder rotor on a six cylinder distributor. The longer spark path makes the problem worse.
D

 

[Keoke]

Yep, thats the solution Johnski, just get that rivit out of there and fill the void with JB weld formed like a new rivit, let it cure and you will be good to go.Also remove the metal plate from the inside too if the rotor will fit snugly on its shaft.-Been doing it for years no rotor failures.---Keoke- /ubbthreads/images/graemlins/cowboy.gif

OH! if you don't like this approach buy a 1985 Jaguar XJ6 rotor same animal, he is just blue, and no rivit- /ubbthreads/images/graemlins/grin.gif

 

[Ed_K]

[ QUOTE ]
Yep, thats the solution Johnski, just get that rivit out of there and fill the void with JB weld formed like a new rivit, let it cure and you will be good to go.Also remove the metal plate from the inside too if the rotor will fit snugly on its shaft.-Been doing it for years no rotor failures.---Keoke- /ubbthreads/images/graemlins/cowboy.gif

OH! if you don't like this approach buy a 1985 Jaguar XJ6 rotor same animal, he is just blue, and no rivit- /ubbthreads/images/graemlins/grin.gif

[/ QUOTE ]

I think we should put these two tips in the knowledge base for future reference. /ubbthreads/images/graemlins/computer.gif

 

[bighly]

Johnski,

Look for NOS rotors perhaps on ebay. I keep a half dozen plus at least one prewired cap in my trunk (all NOS). Believe me this problem WILL leave you on the side of the road. There are at least three brands that are good, Lucas (real ones), Echlin, Bosch and another German brand that eludes me. Avoid "new" Lucas caps and rotors.

My advise for those who purchased Moss Lucas rotors and caps about 4 years ago is to get good NOS spares. Carry at least these and a spare fuel pump and filter.

How might I know /ubbthreads/images/graemlins/devilgrin.gif

 

[healeyneil]

When mine went it took an age to figure out. Car would run fine for about 40 miles then develop a misfire and would eventually die at the side of the road. Half hour later it would be fine, during which time I would be checking and cursing in equal amount. Like Bighly I bought some old stock on ebay and they are in the car at all times

 

[Keoke]

Just take the rivit out and they will all be good to go.---Keoke-- /ubbthreads/images/graemlins/hammer.gif

 

[Johnski]

Thanks to all who responded, I will try getting rid of the rivit and also buying a jag rotor. Two easy cheap solutions

 

[bighly]

For early 3000 and 100/6

Distributor Cap Lucas 418861
Rotor Arm Lucas 418726
Set of points Lucas 420197

 

[AlanT]

I was curious about the Jaguar rotor so I got one off the shelf and compared. I show a DRB133/JLM9623/54401113 rotor for a later XJ6 with electronic ignition. It fits fine on the shaft of the TR6 distributor but is about 1/16" narrower in its sweep. Conversely , if I put the point type rotor on the XJ6 distributor it jams against the contacts of the cap.

More questions than answers,

Alan T

 

[anthony7777]

gents,its obvious this is an example of a "german" one ive been getting from a local sports car parts place $9.00 been working just fine,it does have a rivet but no problems except i never asked the name of the manufacturer /ubbthreads/images/graemlins/smirk.gif, will do so i near future.only other markings are on top "remove to oil". /ubbthreads/images/graemlins/savewave.gif i also tried the jag trick it didnt work for me either-keoke?. /ubbthreads/images/graemlins/confused.gif

 

[Keoke]

7777, I used the Electronic version of the 1985 Jag XJ6 rotor in the Healey Dizzy,and it works ok.Of couse I do not use points so?---Keoke

 

[Dave Russell]

A related note - If using a Pertronix ignition, some combinations of the slip over breaker cam sleeve, the rotor height, & the cap contacts for plug wire heights may result in the rotor sitting high enough to contact the cap terminals. This will break the cap or the rotor. It only happens when the stackup of tolerances comes out wrong.

Check the fit carefully for rotor arm to cap contacts clearance. If the Pertronix sleeve is seated as low as it can go on the cam, the solution is to trim a bit off the bottom face of the rotor so that it can sit down further on the Pert. sleeve, or to find a rotor that sits lower, or a cap with the contacts positioned higher. Trimming the bottom of the rotor is easiest.
D

 

[jlaird]

Dumb question, my Bugeye roter says remove to oil as well. Oil what??

 

[AlanT]

These distributors started life with a piece of oil-soaked felt under the rotor. It was to lube the mechanical advance shaft. If you grab the rotor you should be able to move it the number of degrees stamped on the rotor shaft (cam). If not then the mechanical advance is not working. I made a tool a long time ago to remove seized shafts to clean and oil them. I probably have found over a hundred seized.

Alan T

 

[jlaird]

Oh my word, I remember now, and you are abolutely correct, a bit of felt and a drop of oil. I had forgotten all about that.

Thanks for joging an old brain.

 

[Johnski]

FYI, I bought the Jaguar rotor, It was too high at least for my petronix ignition. Filing the bottom of the rotor did not make it work either.

 

[Keoke]

--- /ubbthreads/images/graemlins/savewave.gif
I will confess, because the rotor was blue and in my Jag spares I assumed it was from my Jag it is not and I do not know what car it came from as there are no markings on it. However, I stand firmly behind my suggestion that you remove the rivit from the Lucas type rotor and resecure the contact with JB Weld to preclude rotor failure.---Keoke- /ubbthreads/images/graemlins/yesnod.gif

 

[bighly]

One of the cars on the Nelson after tour had ignition problems so I put a Moss/Lucas rotor on. It cracked after 100 miles and was tossed into the woods by owner with great frustration. We were all a bit ticked as it was fine when it went in. We put a different rotor on and solved the problem. The rotor was cracked but the rivit was still in solidly. No glue/duct tape or bailing wire involved.

Moral - Get good rotors and plenty of them. If not for you at least for those on tour with you.
/ubbthreads/images/graemlins/pukeface.gif