Took our '54 out for the usual 80 to 100 mile drive Sunday and about 40 miles into the cruise the car started to misfire. I pulled over, checked the visual stuff, nothing out of order then drove the 40 miles back home with the engine misfiring all the way. Put it in the garage and pulled the distributor cap and this is what I found.... Funny thing is, the car idled perfectly. I had a spare rotor in the glovebox and we're back on the road but this is a little puzzling. I'm hoping it was a defective rotor, as it's only been on the car for about a thousand miles along with a good used distributor. Any thoughts? DSCN0417.JPGDSCN0415.JPG T. Irvin
Are you using stock points and coil? I've burned many rotors when I used pertronix ignition and a high voltage coil. If you're stock, check the wiring to the coil and make sure the wires are in good condition and connections are tight. I'd also check the spark plug wires and spark plugs themselves, and if it has been a while, I'd simply replace them.
With that much damage to the rotor the cap at the very least has to be full of conductive carbon so that should be replaced too. Can you post a photo of the inside of the cap? I'm curious what its looking like and if we will be able to tell how well aligned the spark is with the terminals.
Check the gap on your spark plugs, maybe reduce the gap a little.
Make sure you coil is either internally resisted or you have an external resistor to a 12v coil.
All stock engine rebuilt at 114K now has a little over 130K on it. Dwell is rock steady at 30 degrees...new plug wires, NGK plugs set at .035, points, all at the time I replaced the distributor but I did not replace the condenser. The terminals on the cap still look new, no arching or the normal "white stuff" that accumulates after many miles. The points are still shiny. After I immediately spotted the bad rotor, I inspected the cap for defects, none that I could see. I blew out the debris with compressed air and sprayed the cap with Zep electrical cleaner, put in the spare rotor and have put maybe 30 miles on it and it runs great again. I'm wondering if the rotor was defective because the cap contact is stainless and the cap terminal contact is brass, I believe. So maybe where the two should come together there was a fault...it looks to have burned from the inside outward. These rotors aren't cheap, $39 at NAPA but I got one from Rock Auto for $26 with shipping. T. Irvin
This car still has the ballast resistor on the firewall and the wires have never been messed with...12v to the coil when cranking and around 8v when running. If the voltage was higher when running, my understanding is it would burn the points prematurely? T. Irvin
It looks to me, like the (arc) point of the rotor
fell off or got broken by some cap mis alignment.
Then the spark continued to jump the now huge gap,
most of the time, if you did not push it hard.
Bruce Roe
Terry,
If that rotor is an OEM I believe some of the older OEM had an internal resistor built-in in the rotor. I recall that our late friend Johnny Washburn had a SS article detailing his finding on these old OEM rotors.
So it is possible yours was arching across and burnt right through the insulator. ??? ???
Mr. Gomez, I believe you are correct. I found a small 1/8 inch round by 3/4 inch long "thing" laying on top of the distributor plate. I fished it out when I was blowing compressed air on the distributor innards. I'll dig it out of the garbage and take a photo if possible. T. Irvin
Here it is.DSCN0418.JPG I can see two small "points", one on each end that appear to have had wires attached. Now to figure out what caused this resistor to fail...age? T. Irvin
That sounds like it might be the piece. Clay/Lexi
Terry,
I'm with Clay's comment above..!
Unfortunately I do not recall the year/month on Johnny's SS article, from memory he mentioned/show the resistor to be about the same as the one in your picture and place in between the center tab and the end.
So as your prediction "yes" is age and contamination, I believe those resistors are "carbon made" and in Johnny's SS article he stated that NOS in their box and never installed he checked failed. :o
So even getting a new NOS rotor may not worth the $$ and the time to search for them. :( At least you were lucky in limping back home with no major issues. ;)
Good luck..!
The replacement I had doesn't say made in the USA so I'll take it that it's not OEM. The one coming from Rock Auto will go back in the glovebox. What really amazes me is the fact that it idled perfectly after I got home. I shut it off cause I have to manually lift my garage door and it started right up like it always did...fired on the first piston. I drove home about 55 to 60 mph, all two lane highway and I could feel and hear ( I have the resonators AND the mufflers installed) it firing through an adjacent exhaust valve!! I'll consider the problem solved unless it happens again. Thanks for all the input fellas. T. Irvin
Standard Motor Products (DR306) which is made in the USA can be had for $26 on Amazon.
Very common failure. Betting you have modern resistor plugs & resistor wires.
A definite NO-NO with a resistor rotor.
Run a standard rotor with modern plugs & wires and you will be set for the next ten years!
Oh, and welcome the the "club" :)
Quote from: J. Gomez on November 01, 2022, 01:10:27 PMTerry,
I'm with Clay's comment above..!
Unfortunately I do not recall the year/month on Johnny's SS article, from memory he mentioned/show the resistor to be about the same as the one in your picture and place in between the center tab and the end.
So as your prediction "yes" is age and contamination, I believe those resistors are "carbon made" and in Johnny's SS article he stated that NOS in their box and never installed he checked failed. :o
So even getting a new NOS rotor may not worth the $$ and the time to search for them. :( At least you were lucky in limping back home with no major issues. ;)
Good luck..!
Yes, Jose nailed it. I went through my parts and found an NOS Rotor for a 1956 Cadillac. MPL lists part # 1932135. Here is the box plus the "offending" resistor highlighted. Clay/Lexi
Nicely done gentlemen. You guys would put Columbo to shame!
Since there are so many parts involved I would think maybe the failure was the rivet at the outboard end got loose? Seems strange that much damage happened that fast and that for the most part it ran good.
Was the resistor in the rotor the same idea as the resistor wires?
Quote from: J. Gomez on November 01, 2022, 01:10:27 PMTerry,
I'm with Clay's comment above..!
Unfortunately I do not recall the year/month on Johnny's SS article, from memory he mentioned/show the resistor to be about the same as the one in your picture and place in between the center tab and the end.
So as your prediction "yes" is age and contamination, I believe those resistors are "carbon made" and in Johnny's SS article he stated that NOS in their box and never installed he checked failed. :o
So even getting a new NOS rotor may not worth the $$ and the time to search for them. :( At least you were lucky in limping back home with no major issues. ;)
Good luck..!
I also remember seeing a SS article on the rotors by John Washburn,
Does anyone know how to search for that article? If so please let us know.
I miss my friend, technical and tool advice from JW.
Bob
TJ, yes, the Carbon rod was before resistor plugs & resistor wires. Combine all 3 and you will need a tow truck.
@TJ,
That would be correct those type of rotors were used with the old Packard copper-core ign. Wires my understanding supposedly to reduce the cross/wire arching.
@Bob,
Same here..!
I could not find that article in the 2018-2019 section and there are a few under 2020 (01, 02 and 03) which are not working, hopefully any admin on the site may have access to them and possible fix the errors are well.
I remember that specific article was after the one he posted on my Rochester fast idle speed-up control rebuilt on 03/2019. So it could well be on one of the ones in 2020 that do not work.
Quote from: Scott Nellis on November 03, 2022, 02:25:33 AMNicely done gentlemen. You guys would put Columbo to shame!
To quote Columbo himself; "(We)...just like to tie up some loose ends"... Clay/Lexi
@J. Gomez Thank you for the information, I also had trouble with 2020 (01,02,and 03) on line, I did contact the CLC office and waiting for response, mine had error code of 403? I will keep searching on my end.
Bob
Quote from: J. Gomez on November 03, 2022, 05:45:01 PM@TJ,
That would be correct those type of rotors were used with the old Packard copper-core ign. Wires my understanding supposedly to reduce the cross/wire arching.
@Bob,
Same here..!
I could not find that article in the 2018-2019 section and there are a few under 2020 (01, 02 and 03) which are not working, hopefully any admin on the site may have access to them and possible fix the errors are well.
I remember that specific article was after the one he posted on my Rochester fast idle speed-up control rebuilt on 03/2019. So it could well be on one of the ones in 2020 that do not work.
I checked my Self Starters for January, February and March 2020 and there were no John Washburn articles on this issue. I think it was in the Feb issue he did mention rebuilding his distributor from a '49 Cad, but nothing on the rotor. Clay/Lexi
Yes, Ponch, I have modern 8mm plug wires and modern NGK plugs. I'm never too old to learn something new so this stuff is right up my alley! DSCN0420.JPGDSCN0421.JPG I know, I know, the decals don't belong on the '54 valve covers or the pretty blue plug wires but I like the looks. Car is painted in original "Driftwood" with "Copper" poly top as per cowl tag...14Z. T.Irvin
Quote from: Lexi on November 04, 2022, 09:52:28 AMI checked my Self Starters for January, February and March 2020 and there were no John Washburn articles on this issue. I think it was in the Feb issue he did mention rebuilding his distributor from a '49 Cad, but nothing on the rotor. Clay/Lexi
Found it! On page 29 of the May 2016 Self Starter "The Johnny" wrote a piece called; "He just couldn't resist". Lots of photos, and as usual, a fantastic article by John. Clay/Lexi
Note: John also featured a vintage image of a tech update noting Distributor changes. This reference came from page 57 of the November 1956 issue of the Cadillac Cadillac Serviceman. Upon review, I have determined that the rotor that I posted an image of earlier in this post is of the original rotor as I stated, though the box features the double "XX" markings, (see previous image posted). Both "X" and double "XX" boxes contain (or should contain) revised rotors. The Serviceman directed that all original rotors be returned and that only those bearing an "X" or a double "XX" be used. John claimed that the "newer" rotors abandoned the resistor. Therefore, I infer that my double "XX" box originally contained a non-resistor type 1956 rotor, if John's research is correct, (he had a collection of rotors still in their boxes). Seems the glue holding the resistor would let go, hence the reason for the change, though John described how to repair them using a dab of high heat clear silicone.
Quote from: Lexi on November 04, 2022, 10:41:33 AMFound it! On page 29 of the May 2016 Self Starter "The Johnny" wrote a piece called; "He just couldn't resist". Lots of photos, and as usual, a fantastic article by John. Clay/Lexi
So there you go leave it to Clay aka Mr. Sherlock Holmes 2.0 to find the MIA article..! :)
No need for Clay to use the old traditional magnifier glass he uses the modern electronic sniffer..! ;D
Thanks Clay. ;)
Update, I received a reply from Stefan Bartelski, he made corrections and the links are working now, on my end they are, so try yours for 2020 (01,02,03) on line.
Thank you very much Clay/Lexi "AKA Mr. Sherlock Holmes"
and also a thank you very much to J.Gomez, both of you members are GREAT.
The article is BETTER than I remember it to be!
Bob
Bob, I agree. That article was better than I remember it as well. John was a fantastic writer and researcher. As for "Sherlock Holmes", I am still learning from Jose who several years ago I deemed him to be one of the "Cadillac Gods". LOL! Well, another Cadillac mystery solved. Clay/Lexi
I received my rotor from Rock Auto today and it appears that the DR-306 HAS the resistor epoxied into the arm of the rotor. So I pulled the one in the car that currently works and it too appears to have a resistor epoxied into the arm. So I now have to either find non resistor plugs and wires or reinstall the '56 distributor that was on the car when I got it but will have to have the vacuum advance rebuilt by Terrill Machine. The turnaround for the vacuum advance is about 2 to 3 months, cost around $100 or so. More likely less for plugs and wires in the non resistor variety if I can find them. 3rd option is to go with a Pertronix system which I have zero experience with. Sorry about dragging this topic on and on....T Irvin
See post # 15.
Update. I've driven the car for a year and over 1500 miles by changing nothing but the rotor. The rotor was pulled after the car has been stored for the winter and it looked brand new. I'm going to go on the assumption that the old rotor was defective but will always carry a spare. Thanks T. Irvin
Remember, with Pertronix you must to resistor wires to eliminate rfi.
I'll remember that if I ever put Pertrnoix in this car. T. Irvin
Have come late to this discussion but here are my 2 cents anyway. I've seen this sort of damage to the tips of rotors before, specifically on a '53. I'm wondering if it might be due to the bushing inside the lower part of the distributor shaft being worn, allowing the shaft to wobble slightly. You can test for this with the distributor removed from the motor and the rotor removed by grasping the top of the shaft and moving it from side to side. If you can feel any play this may cause the excess pressure on the tip of the rotor and eventually causing it break off as shown in the photo. I've had worn bushings like on distributors on my '49, probably caused by not keeping the oil reservoir full in the lower part of the distributor. Just a thought...
@Jay Friedman you can also test with dwell meter with engine running at idle and dwell set correctly, and watching the dwell meter take idle speed up slowly to 2000 RPM and watch the amount of variation in dwell meter reading, and if it is a lot of variation from what is was at idle, next step is to pull distributor and inspect distributor shaft and bushings for wear.
Just my 3 cents
Bob
I was just going to say the same thing as Bob. Dwell reading will show a worn bushing because the reading will vary with rpm and possibly even at a steady rpm.
I'm think the wear would have to be pretty bad to cause that contact issue. By the time I would expect the contact to be out of range the dwell would be so bad I would think the engine would barely run. Or is that where we are at here? I assume with a new rotor it runs good for a while?
End play / thrust maybe a problem? With a helical gear I would think running it would tend to stay at one end or the other but maybe when its turning it takes up the slack and pulls away?
One way you may be able to troubleshoot is to drill a bunch of holes in an old cap so you can look in there while its running. Depending on the model you may even be able to buy a clear cap if you really want to see whats going on. Timing light on various or the coil wire may show things you can't see with regular lighting. A strobe light app on your phone could also show you stuff. Who knows maybe that thing is flopping all over the place while its running.
Quote from: CadillacFanBob on November 13, 2023, 06:24:36 PM@Jay Friedman you can also test with dwell meter with engine running at idle and dwell set correctly, and watching the dwell meter take idle speed up slowly to 2000 RPM and watch the amount of variation in dwell meter reading, and if it is a lot of variation from what is was at idle, next step is to pull distributor and inspect distributor shaft and bushings for wear.
Just my 3 cents
Bob
Thanks Bob and TJ Hopland. You learn something new every day on this forum. Jay
I work with an older mechanic when I do my tune ups and he stated all the older rotors were black and they were problematic. He did not state why but all the new AC Delco ones are tan now.
Apparently when making black things like distributor caps originally they used some sort of toxic elements that also became expensive. This happened after the real engineers were out of the picture so someone at the factory just went to the next black product in the plastics catalog which apparently was somewhat conductive especially in humid environments. I don't think every brand had this issue but enough did have the issue that the black ones got a bad reputation.