I've now experienced this twice....the first time my fault for not noticing and the second time I get to blame it on the PO or their mechanic.

I have found with the P unit, that if you use a Bosch Rotor, it rubs, creates dust and causes the car to run like shit. When you put it on, it doesn't seem to interfere, but when the car begins to run like crap, it has rubbed.

The first car has a grey aftermarket rotor in it when I changed it to Bosch. A couple of weeks later, it began to run like shit. After going thru all the motions and finally pulling the dizzy cap, I saw the dust. Pulling the rotor you could see where it scraped. I threw the unit away and put in a Crane/Allison Optical.

The second car I bought. It has run fine for about 3000 or so miles. It started to run like crap and I thought it was bad gas (gasoline..not me). After investigation, there was the rotor a scraped up. Some grinding and things are a little better. I still going to throw the piece of shit away and install a Crane/Allison.

Moral of story....none....just a warning for those that want to mix a Bosch rotor with a P unit. The Bosch must be slightly thicker than others.

Ok, so I'm just stupid...........Take your shot Z.............

What part of rotor is scraping on what?

I haven't experienced this yet.

I had the same problem. Destroyed one brand new cap. Finally I figured out that I didn't snap that ring down far enough and thus the rotor sat too high. After I got the ring seated the Bosch cap/rotor has been fine.

I agree that the Pertronix isn't a great fit. The tolerances are less than perfect.

Tole U so.....

It rubs on the barrel of the rotor...the part that slips over the point cam.

Apparently, if the clearance is set with an aftermarket rotor (grey) and you replace the rotor with a Bosch (orange?), the bosch is thicker in the barrel and will possibly rub against the sensor.

I wish I knew what this rubbing does to the sensor.

I posted this in case someone is running a Petronix, changes rotors and a few weeks later the car starts running like shit...it's a place to look.

My guess is, the rubbing does nothing to the sensor. It's a Hall-effect doodad, relying on the field of the magnets in the Pertronix ring. Plastic dust shouldn't affect it. It may run like shit because the rotor may push the sensor out of adjustment some. Hall-effect sensors usually require a pretty small clearance to work properly. I'm assuming the "plastic" isn't conductive. If it is, that WOULD affect the operation of the sensor, but cleaning it off should clear things up again.

Sounds like the thicker Bosch rotor needs to be turned down a bit on the base. It also sounds like the distributor has a bit more axial play in the shaft than is good for it. This would also cause the cap destruction Anthony mentions.

Interestingly, any clearance problems on a Crane WOULD affect the sensor, since the plastic dust would eventually cover the IR led or the phototransistor.

On the usual Pertronix V. Crane subject: it was pointed out on one of the auto electronics boards that there have never been any OEM ignition systems that used an optical sensor as the trigger. There have been a couple that used a Hall Effect. However, the majority of OEM systems, both in distributors and crank fire, have used a variable reluctor (VR) sensor. This is very simple (a coil of wire and a magnet), but requires a ferrous metal toothed wheel to work. GM used VR triggers in distributors for years on millions of cars. Bosch used it, too, though they used Hall Effect on some earlier systems.

I cleaned the sensor off (and the dizzy) with compressed air. It still doesn't seem right and my timing appears to have been really retarded from the rubbing. (didn't hit it with a light)...just timed by ear for the moment...real timing tomorrow.

That is why I wondered if the unit is altered by the rubbing.

fit fine in my 050....

must be a stock dizzy issue...

QUOTE (anthony @ Apr 6 2005, 03:50 PM)

I had the same problem. Destroyed one brand new cap. Finally I figured out that I didn't snap that ring down far enough and thus the rotor sat too high. After I got the ring seated the Bosch cap/rotor has been fine. I agree that the Pertronix isn't a great fit. The tolerances are less than perfect.

I just installed a Pertronix Ignitor last night on my car. I couldn't get the cap to seat because the rotor was interfering with it. Turns out the cam magnet, although it felt seated, needed an extra strong push to fully seat. I know you'll think that I just didn't install it carefully the first time, but I can only say that the magnet snaps into place and for all the world seems like it is on correctly when it needs to seat another notch. I was afraid of breaking it with the force required to get it fully on, but it eventually just cleared whatever flange it was hanging on and now fits perfectly. No more issue with the rotor clearance.

So just take an extra look and make sure that isn't part of what is happening.

I had the same problem as Chris. As soon as that ring snapped farther down in place all was well. Before that the rotor was sitting too high, fully compressed the carbon contact in the cap and wore in down in a short number of miles. It had nothing to do with play in the distributor.

This is a stock 74 2L distributor.

I had this problem before too. I think the potting compound is thin where the rubbing occurs and the electronics are damaged, maybe by the heat from the friction where it rubs. The sensor fits tightly enough you can't adjust it away from the rotor since it also is up against the cap. Reducing the od of the rotor base is what has to be done to get it to fit. It's a PITA but otherwise the pertronix units work real good.

I just met a guy today on my route and we started talking cars and found out that he was a machinest and did some R&D for CB Performance. He then ran to his shed and pulled out a bosch distributor with electronic ignition that he fitted off of some GM car. He then said "Wanna know a little secret? Their fuel injection is nothing but an early Sunbird setup." Hmmmmmmmm

In reading this thread over again, it sounds like it is the side of the rotor base that is contacting the unit mounted on the points plate.

Are you using the spacer that they provide? If so, maybe the Pertronix is sitting too high. The instructions say that you should have the bottom of Ignitor aligned to the bottom of the round magnet, which will also align the tops. When I first installed it with the spacer plate, it sat too high relative to the magnet. Removing the spacer gave me very good alignment, and keeps the top of the Ignitor pretty much even with the top of the magnet, which means it is below the base of the rotor so it can't interfere in that plane. This is on a '74 1.8 stock L-jet so your mileage may vary.

Just something to look at...

QUOTE (SLITS @ Apr 6 2005, 07:56 PM)

QUOTE

I wish I knew what this rubbing does to the sensor.

When it is rubbed it it gets hot.

QUOTE

That is why I wondered if the unit is altered by the rubbing.

Your unit will be altered. It will expand with heat. Later, it will become stiffer and more brittle. Eventually it may break off.

QUOTE (lapuwali @ Apr 6 2005, 04:10 PM)

On the usual Pertronix V. Crane subject: it was pointed out on one of the auto electronics boards that there have never been any OEM ignition systems that used an optical sensor as the trigger.

Hmmmm... makes no difference here... but there has been at least one "opticlally" trigered distributor. The GM "opti-spark" fitted to LT-1's in camaros, firebirds, and corvettes. Its a decent unit but fails missrably if the water pump leaks. It suposed to be a "sealed" unit, but the coolant finds its way in and kills the sensor.

I think I've mentioned it here before, but I had the same sort of problem with a Compufire set-up. The stock rotor was too tall (stock 1.7 F.I. distributor) for their system and as the rotor spun, the cap would "dance". I filed down the base of the rotor and everything was fine. E-mailed Compufire and their reply indicated that it was a somewhat common occurrence with Bosch distributors.

Ron

Of the two I spoke about, I did not install either one...the POs did.

I'm gonna change it out for a Crane or points just to make sure I'm not fooling myself that I didn't fry the engine

Ah well....the intermittent joys of teener ownership.

hmmmm...prob's here too...I'll get back to ya...

This is a known problem with Pertronix. It fits fine in the non-vacuum-advance distributors, but is a little too tall for ones with vacuum advance like the stock 914-4 distributors.

There is supposedly an equivalent unit with a part number ending in "V" which is just short enough to fit the vacuum advance distributors. Haven't seen it myself.

You can take a Dremel to your rotor or (if you're careful!) to the Pertronix magnet ring to make clearance.

--DD

QUOTE (Dave_Darling @ Apr 7 2005, 12:44 PM)

This is a known problem with Pertronix. It fits fine in the non-vacuum-advance distributors, but is a little too tall for ones with vacuum advance like the stock 914-4 distributors. There is supposedly an equivalent unit with a part number ending in "V" which is just short enough to fit the vacuum advance distributors. Haven't seen it myself. You can take a Dremel to your rotor or (if you're careful!) to the Pertronix magnet ring to make clearance. --DD

I have a couple of "V" part number Pertronix units on the shelf. I have used the units for years and never had troubles with rubbing or even failing. But then, I know better to make sure I install the right part in the correct dist. Did you know there is also a left or right unit depending on how your points are set up? Piont is, you can't just order a pertronix unit and throw it in. You have to make sure it is the right part for the job.

That said, I always carry a set of points in my cars, just in case.

QUOTE (Root_Werks @ Apr 7 2005, 01:35 PM)

QUOTE (Dave_Darling @ Apr 7 2005, 12:44 PM) There is supposedly an equivalent unit with a part number ending in "V" which is just short enough to fit the vacuum advance distributors.  Haven't seen it myself. --DD I have a couple of "V" part number Pertronix units on the shelf. I have used the units for years and never had troubles with rubbing or even failing. But then, I know better to make sure I install the right part in the correct dist. Did you know there is also a left or right unit depending on how your points are set up? Piont is, you can't just order a pertronix unit and throw it in. You have to make sure it is the right part for the job. That said, I always carry a set of points in my cars, just in case.

I just checked the part number of the unit I installed two nights ago and it is 1847V and it fits perfectly. The unit height is such that its top is even with the top of the magnet ring. Since the top of the magnet ring is the below the bottom of the rotor there is no way for the rotor base to rub. The stocking label says "Fits Bosch 205, 009, and 050 Distributors".

Pertronix units are great, only time I had a dead one is when i killed it by cranking the car with no spark plugs hooked up (compression test) I should have pulled the coil hot wire first!!!!

I have ran into one Bosch rotor that rubbed, on the sides of the rotor on one end. A quick file job, and it was repaired, subsequnet Bosch rotors did not have this problem! So the problem appears to be in the rotor diminsions, they were not even close to the same.

Ran one Pertronix for near eight years, worked everytime, no more points adjustment, heaven!!!

Also have ran Pertronix on my VW's, and friends cars.

As mentioined, optical system are prone to dirt issues, the Pertronix does not, and is a clean install with near stock appearnace (no extrernal boxes).

I think later Pertronix are made smaller, (can anyone confirm this???) if so, maybe all clearance issues are solved??