Distibutor cap and rotor

[WmWatt]

How long (miles, km) should the cap and rotor last? Mine has about 32k km (20k miles?) on them and look pitted. Car runs okay with slight miss showing up on vacuum guage. I'd like to get rid of the miss. So far I've cleaned and gapped the plugs and wiped down the wires, cap, and rotor. I cleaned all the contacts on the coil. The vacuum guage quieted down from what I did so far. I took the car in for the emissions test recently and noticed the needle on the machine dropping while the car was in fast idle. That's why I got out the vacuum guage and took a look. The car passed the emissions test with a wide margin so that's not a problem.

What kind of metal is best? I still have the last set. The old rotor appears to be brass. The old cap appears to be aluminum. The current cap and rotor appear to have a coating on the contacts which I assume is platinum. The platinum is pitted. There are no burn marks. I've been looking at caps and rotors on the Internet but none say what kind of metal they use. Is there any way to tell?

Thanks for you help.

[ryanprins13]

They look pitted very fast. Best i think is to carefully clean them often. Replacing them never solved any of my problems but i think the longest i kept one was maybe 80 or 100k km.
The way to check them for sure is to rotate engine slowly and check resistance between input and the 4 outputs. I dont have that info handy right now, anyone else? Also measuring resistance on spark plug wires is the best way to check them too.

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[Team Lightning]

The factory disty cap and rotor lasted 99,000+. It started missing and I changed it right before 100K. Never had one last that long since.

[ricko1966]

This is a very broad very general statement that applies to all auto parts.This has been my profession for decades and I hope someone can benefit from my expierience. Auto parts is a big game,who can price what for how much and still get people to buy it,the game changes constantly also and people never knew or forgot the old rules. A reputable brake job used to include kitting the rear wheel cylinders it was even advertised as included in the price,if you say anything about putting in a kit now someone immediately pipes up with just buy cyls from rockauto they are only 2.99. Well the cheap cyls are cheap for a reason they are an inferior china or india copy of a good part.This gets way more involved than most of you care about but as an example when I was purchasing agent for a parts store I used to try to source original equipment parts {O.E.} some sneaky bastard opened a cheap third world parts company named O.E. so when you you looked through the sales info it said O.E. master cyls,gasket sets,etc. but you were buying junk.Anytime I can source original equipment parts thats what I prefer to use that means if standard ignition made my original cap rotor whatever I try to source standard, if bosch made my fuel pump injectors whatever I try to source bosch etc. then I am getting products that lasted and fit like what I took off. FWIW parts that can be repaired or rebuilt I trust myself as the best person to rebuild.repair it because I am not going to skip replacing a bushing,bearing,seal,whatever,or use a chineese bearing etc. in an effort to cut cost and lure in people that don't know the difference.Easiest example I can make is a jenos pizza is a pizza and it's cheap.it is not as good as a papa johns pizza,which costs more,and if you have the skills you can make your own pizza that is better than jenos and maybe better than papa johns, because you care more.I am not accusing anyone of anything only sharing info. some of you may not know.

[ryanprins13]

This is a very broad very general statement that applies to all auto parts.This has been my profession for decades and I hope someone can benefit from my expierience. Auto parts is a big game,who can price what or how much and still get people to buy it,the game changes constantly also and people never new or forgot the old rules. A reputable brake job used to include kitting the rear wheel cylinders it was even advertised as included in the price,if you say anything about putting in a kit now someone immediately pipes up with just buy cyls from rockauto they are only 2.99. Well the cheap cyls are cheap for a reason they are an inferior china or india copy of a good part.This gets way more involved than most of you care about but as an example when I was purchasing agent for a parts store I used to try to source original equipment parts {O.E.} some sneaky bastard opening a cheap third world parts company named O.E. so when you you looked through the sales info it said O.E. master cyls,etc. but you were buying junk.Anytime I can source original equipment parts thats what I prefer to use that means is standard ignition made my original cap rotor whatever I try to source standard, if bosch made my fuel pump injectors whatever I try to source bosch etc. then I am getting products that lasted and fit like what I took off. FWIW parts that can be repaired or rebuilt I trust myself asd the best person to rebuild.repair it because I am not going to not replace this or that or use a chineese whatever in an effort to cut cost and lure in people that don't know the difference.Easiest example I can make is a jenos pizza is a pizza and it's cheap.it is not as good as a papa johns pizza,which costs more,and if you have the skills you can make your own pizza that is better than jenos and maybe better than papa johns, because you care more.

Nice, so by now most ignition parts have been replaced by aftermarket stuff on our cars. Do you know what brand of spark plugs our cars came with from mazda? Or who made the cap and rotor or plug wires?
Price vs quality is always a trade off and most festiva owners go with whats cheap since for example a set of rings for the engine or a set of yokohama 12in tires balanced and installed is more than what you can pick up another festiva for...
And the thing with the cheap $5 brake cylinders is they may possibly fail, but more than likely they will outlast the rest of the car.
I drove my first festiva 9.5yrs always thinking it might die next week or next month and never spent much on it because i was always thinking it wouldnt last mich longer... :/

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[ricko1966]

I hope I didn't make anyone mad was mostly trying to inform people that don't know there is usually a cheap part and a good part and usually the cheap part is copy of the original part,not the original part. Maybe or maybe not you would be surprised how many people do not know there is a difference,I've been helping friends or working in a shop and had people actually look at me and say why won't you use this or why don't you recommend this or why does this cost more than I found it for in the house brand at Autozone it is the same ford/chevrolet/volkswagen part? and they actually do not realize that the cheap part is not the same part. I am not saying there are not quality aftermarket parts some are just fine ,but there are lots of inferior aftermarket parts,and a lot of people do not know this. Your plugs and wires were probably denso not saying ngk or bosch or maybe a few others wouldn't be good. I prefer O.E.M. parts when I can find and afford them.About the wheel cylinders I was just kind of reflecting,there because thats one of those things that changed,kitting them used to just part of a standard job,so was repacking servicable wheel bearings I still kit them when can as part of my brake job.

[ryanprins13]

I hope I didn't make anyone mad was mostly trying to inform people that don't know there is usually a cheap part and a good part and usually the cheap part is copy of the original part,not the original part. Maybe or maybe not you would be surprised how many people do not know there is a difference,I've been helping friends or working in a shop and had people actually look at me and say why won't you use this or why don't you recommend this or why does this cost more than I found it for in the house brand at Autozone it is the same ford/chevrolet/volkswagen part? and they actually do not realize that the cheap part is not the same part. I am not saying there are not quality aftermarket parts some are just fine ,but there are lots of inferior aftermarket parts,and a lot of people do not know this. Your plugs and wires were probably denso not saying ngk or bosch or maybe a few others wouldn't be good. I prefer O.E.M. parts when I can find and afford them.About the wheel cylinders I was just kind of reflecting,there because thats one of those things that changed,kitting them used to just part of a standard job,so was repacking servicable wheel bearings I still kit them when can as part of my brake job.

I dont think anyone could have gotten mad at what you said.
I didnt realize people didnt know that the parts are different :/
In autobody the aftermarket parts HAVE to be different. You can buy a GMC fender which in theory should fit exactly for say $600. Or you can buy an aftermarket fender. Aftermarket companies are sent dimensions by the oem or find the drawings but they HAVE to be different. There is a certain tolerance level which they are not allowed to be within. You can buy a CAPA certified fender for like $300 which is supposidly garunteed within a certain measuerment, say within +-2% of oem measurements, but they arent allowed to be within say +-0.5% of oem measurments.
Then you can also buy a non capa fender for like $150 which also cant be within the +-0.5% but may be out 5% and thats too bad, so sad if it doesnt fit well.
I presume the same goes for mechanical parts. There is a patent on the exact measurements or composition of the oem part and the aftermarket companies have to either make it with different materiels or a slightly different size to avoid being sued or whatever.
Thats the long explanation, lol.
Like you said, sometimes it makes no difference that its slightly off size, different materiels or different process but sometimes it makes a big difference like say on piston rings. Other times the point of the aftermarket part is to fix a defect in the oem part and its actually better.

And i know other brands of plugs and wires work just as well, perhaps better than what the car came with, i was just wondering what it did come with. I hear mazda uses denso and ngk now, just havent been able to find what they used back then.


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[ricko1966]

yeah,funny a friend told me last month his sons fairly new jetta was at a shop and needed an alternator he was telling me he found one at autozone blah blah blah and had tell him they are alll not the same the shop isn;t robbing you. then a week ago or so he had a minor fender bender in his beater corolla 1997 crappy paint and minor dents everywhere . I said go to pik n pull take one off a junker if you are lucky you might even get one similiar in color 2 days later he's telling me he can get a brand new one for 26.00 from some website and again had to explain it is similiar but different go to the salvage yard similiar money for the correct part and you don't even have to prep it to keep from rusting to pieces in a year.

[ricko1966]

Wow this is crazy, bringing back memories. This will surprise people probably. The shop I worked at for 16 years was a full service independent shop we had our own parts dept. our own in house machine shop. dyno room, flow bench,full service dept. alignment racks, we did fabrication work built big valve heads, transmissions we did everything I can think of in house,sorry got off track,our parts dept for would stock ate wheel cylinders for shop use or customers who wanted better cyls, india, china whatever for price shoppers,same with gasket sets,clutches, even alternators and starters, we sold fenders and bumpers sometimes they were made in italy sometimes spain sometimes who knows. We bought them in boxes of 5 sometimes moving the last old one to the new box you could notice the hole for the marker light,bumper bracket whatever is a 1/2 inch higher,lower whatever.

[Dragonhealer]

Educating clients does seem to be a part of the job.
For some things an aftermarket part is just fine.
On the sparkplugs, I can't remember what I pulled out of the '91 at 60K, but NGK's have treated me right, never had a failure in 60K for many hundreds of plugs.
I would guess OE was probably Denso, just can't recall. They are great plugs too.

To answer the OP's question, the cap and rotor will last forever if they never get carbon tracked (due to something else failing) and the material they are made of does not break down (OEM parts were phenolic)

[ryanprins13]

Wow this is crazy, bringing back memories. This will surprise people probably. The shop I worked at for 16 years was a full service independent shop we had our own parts dept. our own in house machine shop. dyno room, flow bench,full service dept. alignment racks, we did fabrication work built big valve heads, transmissions we did everything I can think of in house,sorry got off track,our parts dept for would stock ate wheel cylinders for shop use or customers who wanted better cyls, india, china whatever for price shoppers,same with gasket sets,clutches, even alternators and starters, we sold fenders and bumpers sometimes they were made in italy sometimes spain sometimes who knows. We bought them in boxes of 5 sometimes moving the last old one to the new box you could notice the hole for the marker light,bumper bracket whatever is a 1/2 inch higher,lower whatever.

Ha, yes, removing the shipping primer and properly finishing and rustproofing one of those fenders is more money than refinishing a good condition oem one thats a different colour. And even then if the paint chips the aftermarket metals dont have the same coatings that honda will use (but mazda doesnt... :/ )
A bodyman that can quickly fit an aftermarket fender is a sought after person! Hard to explain to someone that they are saving $100 on a fender with the aftermarket but have to pay an extra hour of labour to make it fit, lol. And you dont fix blinker holes that are in the wrong spot! thats just bending, filing ridges or bumps down and sloting bolt holes. Some guys are quick at it but i never was that fast at it. Its just hard to take a big file or 36 grit on an air sander to a brand new fender and make spots paper thin just for looks.

Educating clients does seem to be a part of the job.
For some things an aftermarket part is just fine.
On the sparkplugs, I can't remember what I pulled out of the '91 at 60K, but NGK's have treated me right, never had a failure in 60K for many hundreds of plugs.
I would guess OE was probably Denso, just can't recall. They are great plugs too.

To answer the OP's question, the cap and rotor will last forever if they never get carbon tracked (due to something else failing) and the material they are made of does not break down (OEM parts were phenolic)

Cool, they should have coated the entire body of the car with this phenolic [emoji14]
Or at least the bottom half.

This is a good illistration of aftermarket parts. They are still cookies and have calories, but are no where near the same as oreos which i wish i had bought for the extra dollar.... lol.
We all know they cant name it the same without being sued but if they made it the same shape and colour and ingredients they would also get sued.




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[WmWatt]

The original electronics on the Festiva were Mitsubishi if I'm not mistaken. The logo is embossed on a lot of the stuff under the hood. I`ve always thought that`s why the Festiva has weak ignition.

[ryanprins13]

The original electronics on the Festiva were Mitsubishi if I'm not mistaken. The logo is embossed on a lot of the stuff under the hood. I`ve always thought that`s why the Festiva has weak ignition.

I think the alternatkr is a mitsubishi but i havent had a festiva with plugs, wires, cap... thats oem and it seems mazda used a bunch of different suppliers for stuff. However what you said gave me an idea. I just need to find someone with the mazda 121 and see what they got on the hood decals or in the manual. Ford just slapped their stickers and grille on our cars here but im sure they didnt actually put motocraft plugs in before selling.
So anyone got these stickers on a 121? Or a factory service manual that would maybe say?


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[WmWatt]

Just a note to say the missing has been cleaned up, litteraly, by going over the plug wires, cap, rotor, and coil again with a rag and WD-40 to clean the contacts. NOoneed to replace any parts. With the engine runnign and the vacuum guage hooked up every contact was wiggled and pushed on tight until the needle on the guage was steady, no misses. I can feel the difference in response and pep when driving. Followed up a couple more times with the gauge just to make sure and the engine is not missing any more .... good until the next cleaning.