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The erratic advance generally won't cause a misfire, but it will contribute to sluggish performance and the erratic timing you report.
The RPM-limiting rotor can cause a misfire if there's internal damage. Verify the part number and do some searching for whether the one you have is a RPM-limiting version. In those, there's a spring and a sliding weight that open if they are spun too fast. Worth at least a look.
Otherwise... Inspect the green wire carefully for kinks and connector issues. There's nothing "smart" about the system that screws up. It's all mechanical in the distributor and electrical from the distributor to the box, the coil, and back. Known wear pieces include the green wire on the low side, then the ignition wires and spark plugs on the high side. The cap and rotor can easily play a part in a misfire especially if the cap is cracked or is suffering from "carbon tracking" inside; any metal or carbon deposits on the inside of the cap should be completely removed (soap and water), and then inspected for cracks.
The erratic advance generally won't cause a misfire, but it will contribute to sluggish performance and the erratic timing you report.
The RPM-limiting rotor can cause a misfire if there's internal damage. Verify the part number and do some searching for whether the one you have is a RPM-limiting version. In those, there's a spring and a sliding weight that open if they are spun too fast. Worth at least a look.
Otherwise... Inspect the green wire carefully for kinks and connector issues. There's nothing "smart" about the system that screws up. It's all mechanical in the distributor and electrical from the distributor to the box, the coil, and back. Known wear pieces include the green wire on the low side, then the ignition wires and spark plugs on the high side. The cap and rotor can easily play a part in a misfire especially if the cap is cracked or is suffering from "carbon tracking" inside; any metal or carbon deposits on the inside of the cap should be completely removed (soap and water), and then inspected for cracks.
Will check into the RPM limiting and report back -
The Cap, Rotor and Wires are all brand new and appear to be in good shape. Is there any way to test the green wire? - I have done some searching and cannot seem to find any info on this.
Oh, wait a minute! This car has a spark box mounted on the inside fender well, right?
BradW's street beast 82 has a bad misfire at off idle RPMs that we (the collective we) found with an ocilloscope. The ignition signal just completely deteriorated at the same time as the misfire. We replaced that spark box with an extra I had (for some unknown reason)and never looked back.
I had never heard of one of these going bad before that time. The problem only happened beyond a certain RPM.
If all else fails, check that spark box.
Good Luck.
I won't be able to get back into this until the weekend now. I will do some more checking then and report back.
Just to confirm - It seems to me this is for sure some kind of electrical issue - do you all concur ? Is there any way this could be an air/fuel mixture issue ? I want to make sure Im not going down the wrong path here
Troubleshooting is a process of elimination. The selection of what possible causes to eliminate is important. Electrical, at least for me, is the easiest to diagnose and eliminate. It's also the most common cause of odd running in my experience, if you disregard storage-related issues. I have a hammer, and all my problems look like nails.
I would remove the connector from the computer on the fenderwell and put deoxit 100 on it then plug it back in,
same for the green wire connections.
Also pay close attention to the fingers inside the distributor,
if one of them is bent then it can hang and make the dizzy seem dizzy best to turn the engine over by hand to observe the operation of the distributor,
and confirm the roll pin is in place.
I would remove the connector from the computer on the fenderwell and put deoxit 100 on it then plug it back in,
same for the green wire connections.
Also pay close attention to the fingers inside the distributor,
if one of them is bent then it can hang and make the dizzy seem dizzy best to turn the engine over by hand to observe the operation of the distributor,
and confirm the roll pin is in place.
Stan - I removed all connectors and used the deoxit - I also inspected the fingers and they all looked pretty good to my untrained eye.
I am having a hard time confirming the roll pin in the distributor though, it looks to me like the fingers are held in place by a circlip
Here is a photo - Am I missing something ?
I dont think I mentioned this originally but the timing mark is pretty steady at idle. It just jumping around once I get the revs up to 3100rpm.
Troubleshooting is a process of elimination. The selection of what possible causes to eliminate is important. Electrical, at least for me, is the easiest to diagnose and eliminate. It's also the most common cause of odd running in my experience, if you disregard storage-related issues. I have a hammer, and all my problems look like nails.
Dr. Bob - My rotor does not have a rev limiter -
As far as air/fuel goes I did some additional checking of all the new lines I installed and everything checked ok except for two vacuum lines. Both lines that go down to the EGR valve will not hold vacuum. I can pump it up but the pressure drops pretty quickly. Im assuming this is not correct and maybe I need a new EGR. What are the symptoms of a non working EGR valve ? I guess it is also possible that I have the two lines switched, though regardless Im assuming they should both hold vacuum. One comes from the pressure convertor and the other from the thermo valve, I cannot find info on which goes to which.
I will throw this out there because it hasn’t been mentioned.
if your using a digital style advancing timing light, especially Snap-On I have personally have had them do exactly what you are describing due to noise. You may want to try a separate battery to power the timing light to eliminate power supply noise issues just for a sanity check.
This is the slot and pin under the circlip but I don't see it in your photo.
Not to derail but sometimes on cold starts I get a squealing sound from the distributor. Are there replaceable bearings inside?
This photo is great - thanks, now I see where to look - though Im not sure I see this groove in my photo. I will have to check it out when I get home later. Though now I see what it does, its difficult to image the car would run at all if this was missing.
I will throw this out there because it hasn’t been mentioned.
if your using a digital style advancing timing light, especially Snap-On I have personally have had them do exactly what you are describing due to noise. You may want to try a separate battery to power the timing light to eliminate power supply noise issues just for a sanity check.
Brian.
You know I was wondering about the timing gun. Its at least 20 years old and is most definitely not a "Snap On" tool. Probably purchased it at Kragens or similar. I will try it again with a different 12v source. Thanks for the tip.
02-13-2019, 05:09 PM
