It wasn't the Pertronix

[RDKeysor]

To all of the forum members who weighed in on what was ailing my defunct '60 BN7, I can now report back on the issue. It was the rotor, the variety with the rivet on the top often mentioned on the forum. My car stopped running definitively after a nice drive two weeks back. Would not fire at all. Examination found power all the way to the center point on the distributor cap, zip at the plugs. My sense was that the PerTronix, installed by the PO, had failed. My car friend who helped me trace the problem thought it was the rotor or dizzy cap. I ordered the works, new PerTronix, wiring set, distributor cap and rotor. Logically, I installed the rotor first. Eureka. I now have a set of spares but will need to buy a back up rotor. Thanks to all who puzzled over this failure and offered suggestions. I'm sure at least one of you suggested a failed rotor. The rotor removed from the car, I should add, looks brand new!

 

[steveg]

Suggest the Advanced Distributors rotors:
https://advanceddistributors.mybisi.com/product/6-cylinder-ignition-rotor

 

[Keoke]

[h=2]It wasn't the Pertronix--[/h] To all of the forum members who weighed in on what was ailing my defunct '60 BN7, I can now report back on the issue. It was the rotor, the variety with the rivet on the top .
OH! yeah that is a bad fella-----:highly_amused:

 

[RAC68]

Hi All,

Good news.

I second Steve's suggestion and would purchase 2 new rotors from Advanced Distributor.

All the best and enjoy your Healey,
Ray (64BJ8P1)

 

[steveg]

RD - thank you for following up with the eventual solution - makes the thread more valuable for the future.

 

[Keoke]

Hi All,

Good news.

I second Steve's suggestion and would purchase 2 new rotors from Advanced Distributor.

All the best and enjoy your Healey,
Ray (64BJ8P1)

Well
if you have some spare new ones with rivets in them and need a fix now, you can save a $ and time by just drilling the rivet out and filling the void with JB Weld. Then you can spend the $ later.

 

[RAC68]

if you have some spare new ones with rivets in them and need a fix now, you can save a $ and time by just drilling the rivet out and filling the void with JB Weld. Then you can spend the $ later.

An interesting suggestion. Has it been determined that the rivet the cause of the rotor failures? I think I still would purchase one new good rotor for use and use a tested recovered rotor as a spare.

Happy Holidays,
Ray (64BJ8P1)

 

[Michael Oritt]

To all of the forum members who weighed in on what was ailing my defunct '60 BN7, I can now report back on the issue. It was the rotor, the variety with the rivet on the top often mentioned on the forum.

RD--

In the initial thread I said: "I'd suspect the rotor as the more likely candidate before a pertronix and in any case it is easy to test simply by putting in a new one." It was a good guess as it could have been some other component but the rotors with rivets have been indicted in many failures for a while now.

In chasing down problems such as these I find it helpful and productive to start with the easiest and sometimes least expensive fix. Admittedly this does require having what amounts to a spare ignition system on hand, but if one is going anywhere beyond the corner store it sometimes pays to have those parts and the tools necessary to install them in the boot. Electronic ignition systems such as Pertronix are certainly improvements on points sets but we are still talking about a mechanical distributor and coil which is hardly state of the art.

 

[steveg]

RD--

... Admittedly this does require having what amounts to a spare ignition system on hand, but if one is going anywhere beyond the corner store it sometimes pays to have those parts and the tools necessary to install them in the boot. Electronic ignition systems such as Pertronix are certainly improvements on points sets but we are still talking about a mechanical distributor and coil which is hardly state of the art.

100% agree.
Would add that the distributor should be indexed to the block so it can be removed for the replacement work to be done - so the little screws don't get lost down inside.

I'm running Pertronix with a Bosch Blue coil and red distributor rotor from Advanced Distributors and have a lot of faith in this setup, but still carry a spare distributor with points, extra condensers, extra red rotors and a spare coil - they've been needed in the past by other Healeys.

 

[Keoke]

An interesting suggestion. Has it been determined that the rivet the cause of the rotor failures? I think I still would purchase one new good rotor for use and use a tested recovered rotor as a spare.

Yes: Ray
The presence of the rivet reduces the dielectric path length between the rotor's metal arm and the dizzy shaft by at least 50 %.
Consequently, since resistance has the dimension of length the shorter path reduces the electric potential required for breakdown, more commonly called shorting.

 

[steveg]

... Has it been determined that the rivet the cause of the rotor failures? ...
Ray (64BJ8P1)

These riveted-rotor failures have been widely known for years:

 

[Keoke]

Now how n the world could it come loose when it was riveted ?

Maybe:
After a severe electrical breakdown the plastic could have been pulverized releasing the rivet.

 

[RDKeysor]

An examination of my failed rotor reveals that the brass piece moves about a bit despite the rivet being firmly in place. Be assured I would have popped a new rotor in the car if I had one, but since I had to put it on order, I went for the works. Our club president subsequently messaged me that I should carry two spares. I'll probably order the recommended bits from Advanced Distributor, though the shipping costs quoted double their cost. Does anyone know the real mode of failure in the riveted rotors? When it failed without warning during a drive, the plugs never fired again until a new rotor was installed. I'll mention that I have now delivered a nice-looking differential loaned by a club member to a firm in Clearwater that specializes in rebuilds. I am have a 3.545 ring gear and new pinion from SC Parts in the UK installed in an effort to reduce the rpms I'm turning with my Toyota five-speed installed by the PO presumably with the original 3.909 ring. Haven't identified the gear box, but I'm turning around 3000 rpm at 60 mph. I'll be reporting on this adventure when the project is complete.

 

[CraigC]

An examination of my failed rotor reveals that the brass piece moves about a bit despite the rivet being firmly in place..... Does anyone know the real mode of failure in the riveted rotors? When it failed without warning during a drive, the plugs never fired again until a new rotor was installed....

Take a look inside the hole on the bottom that fits over the distributor shaft. To the side that is adjacent to the rivet, you will probably see a burn mark along with some degradation of the plastic. Once that happens, all spark goes directly to ground through the distributor shaft. If you were to look at the same spot on the shaft, you might also see a burn mark.

While I have never seen this on a British car myself, I have seen similar failures on a number of assorted vehicles in my years as an auto tech. Most of the time it was on a non-OEM rotor.

 

[Michael Oritt]

RD--

You'll love the 3.54 set. I have one with a Toyota 5 speed and in top gear I am turning just above 3K rpm's at 70 mph.

 

[Bob_Spidell]

RD,

Just in case no one else mentions it, there is usually a specific break-in procedure for new diffs. Usually, it's take a short run and let it cool, take a longer run and let it cool etc. After the first few runs your differential housing will be near pistol-hot; apparently (logically) hypoid gears generate a lot of friction, hence heat, until they are properly finish-machined (like piston rings). It's also recommended to change the fluid after a suitable break-in period; 500m is typical.

I recommend using an 85W-90 dino gear oil for the break-in; then replace with Redline 75W-90 synthetic gear oil or similar (then forget about it for 100K miles or more). Note the diff fluid also lubricates the rear wheel bearings which, if good quality bearings are used and properly installed will go 100K miles as well. Also, if you have good seals at the diff housing 'snout' and the wheel bearings even the syn oil will not leak.

 

[RAC68]

Just to cap off the rotor disintegration discussion and to play on Craig's comments; most of us have replaced points-base with an electronic ignition, upgraded our coils from the original 25K to 40K volts, and widened the gap in our plugs. Are these upgrades the cause of the electrical breakdown of the rotor and could the substantial increase in voltage and resistance be its prime catalyst? If so, the riveted rotor may be perfectly good for those who have not upgraded the ignition and, those of us who have, may need one designed to the changes. Maybe we are not addressing a faulty manufactured rotor or defective materials but are using a rotor designed to and for the lower specs of an original ignition. This could mean that the riveted rotor could operate reliably for those retaining an original ignition system ... or maybe just an original specific coil.

Having one rotor that would satisfy all is best and what we do expect. However, since we do have this issue and other then the rivet in some rotors, what can we look for to reasonably identify rotors that will reliably handle an upgraded ignition system?

Ray(64BJ8P1)

 

[Bob_Spidell]

I had a rotor fail outright--don't recall if it had a rivet or not, but suspect it did--running with a Pertronix and stock coil. A Pertronix cannot output any more voltage (12+) than a set of points and it won't increase the output voltage of any coil--that is determined solely by the ratio of secondary to primary windings--though the spark may be stronger due to different (faster) rise/decay of the primary voltage switching (cars do seem to start a little easier and idle smoother at low RPMs with a Pertronix, but that may be subjective). It's certainly possible--even likely--that a 'sports' coil could overload stock secondary components; up to and including crossfiring in the plug leads (stranded wire secondary leads would be susceptible to this). I have also experienced arcing across an aftermarket distributor cap--think it was Bosch--which I haven't gotten with a NOS Lucas cap, with just the Pertronix and stock coil.

From all I've read or heard, using a 'sport' coil--there have been many reported issues with the Lucas ones--is totally unnecessary in anything but a highly modified (racing cam, higher compression, higher top RPM for which you'd probably need a billet crank, etc.) and may well cause other issues. If you have missing or poor running with the stock setup slapping a performance coil in will not address the issue (but may possibly mask it, for a while). My otherwise stock setup with Pertronix will throw a 3/4" spark against the block; that is sufficient. Also, 'trick' plugs ('Splitfire,' etc.) are gimmicks, and the only advantage of exotic metals plugs (platinum, iridium) is that the center electrode resists erosion better (that's why modern cars can have 100K miles tuneup intervals). Piston aircraft engines, which usually have dual ignition, have higher idle RPM--that gets checked before every flight--with both systems running, but that is due to having two flame fronts which results in a faster burning charge hence more actual power (and the two systems have to be tuned to fire simultaneously).

 

[Michael Oritt]

On my race cars I try to use the most reliable stuff and change it out frequently before it breaks. I use Bosh Blue coils and have not had one fail--at least yet. I change plugs before every weekend and between sessions if need be due to fouling, etc. I also change rotors every couple of weekends--just because.

I don't do any of this stuff to the Healey and deal with issues as they develop. Whereas I have a $1000.00 or more invested in a weekend (entry fee, hotel bills, tire attrition, race fuel, etc) I have little or nothing at risk when I go for a ride.

Just sayin'....

 

[RAC68]

Bob,

I am not suggesting that the Pertronix is causing the rotor failures but may be a cleaner switch could be gating cleaner voltage from a 40K volt coil charge through the rotor. Also, I am not suggesting that a rotor would just fail as I have had a rotor failure with my original points-based ignition system before my upgrade ... but just 1. My thought is that there may be more rotor failures when the increased voltage from a 40K volt charge is directed by the rotor then may occur when using an original-spec 25K volt coil. Again, I am not suggesting that all rotors are potential to this failure and, maybe those using points and an original spec coil may not be as susceptible to this type of failure. However, it would be beneficial if, other then the use of a rivet, additional characteristics were known that could help identify those rotors that have shown the greatest potential to fail.

Ray (64BJ8P1)