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The distributor should NOT vibrate! |
Look at the pictures inside the cap in post #1 (if you can avoid the optical illusion).
Not only are there carbon traces between the contact point but it appears the tip of the rotor is scratching the side of the distributor cap.... the source of the virbration? |
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The scratches on the tip of the old rotor were from me sanding it to try to remove corrosion. I haven't seen any marks on the new rotor. I'll look carefully tomorrow. I'm also going to grab my timing light and verify that the dizzy-coil wire is or isn't firing properly. Presumably I should see 3 positions of the crankshaft wheel, because it is firing 3 times per two rotations, right? |
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SmileWavySmileWavySmileWavy Op could not initially seat the new cap, new rotor appeared to be not fully seated, down... Distributor shaft was for some reason in the "up" end play position? Pictorially Ops distributor is rotationally very close to the one in my '78. If you look closely at the rotor tip and the copper "contact" points on the cap it seems obvious that the clear majority of sparks are occurring with the tip properly aligned. Once it warms up, probably. |
OsoMoore,
Here are the things I would consider looking into further as next steps. - Failing coil. The coil could be struggling to fire. - Bad grounds. Check and clean. The spark plug grounds itself by being screwed into the case. - Bad plug(s). Plug gap too large? - Failing plug wires. - Distributor. Verify that the rotor is properly aligned. This is a 5 minute job. Check for vertical and lateral play. I believe you proved the rotor is seated properly the other day. Worst case, you replace the coil, plugs and wires and it doesn't fix the problem and you have done regular maintenance. But you have also eliminated possible contributing factors so you're closer to narrowing down the problem. The best path for the electrons is not happening. Don't lose sight of that. It is trying to tell you something. I'm going to re-read your last post about possible vacuum leaks and respond shortly. |
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The low noise does sound like a possible vacuum leak. By taking the oil fill cap off you're making it worse. The engine running more choppy when you do that is consistent with that. The combination of vac leak and poor spark is not good. Now is the vac leak related to the spark and distributor? It sounds to me like they are separate issues. Does your dizzy have the advance/retard vac ports or just advance? Retard is an emissions thing that affects idle. If you have it, just disconnect it and plug it with a golf tee. The advance vac should not be an issue. The dizzy uses mechanical advance as the primary mechanism and vac is additional assistance. It should not be affecting anything at idle. So I would focus on addressing the spark issue first and then chase down a possible vac leak next. That green dizzy wire is starting to look ratty. It is not a question of IF it will need to be replaced, just WHEN. Sorry if you mentioned this already, but I don't recall. What CDI are you running? |
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CDI is a Bosch 0 227 300 004.
I hooked up a timing light and see lots of interesting things. I'll post details when I understand it further, but essentially some cylinders are firing when it is not their turn. And the main coil wire sometimes isn't firing when it should. The timing light is very awesome! The rotor seems solidly in place. You can pull it outward a little, but it springs right back down. The markings on the new rotor seem to fall within it's contact point. |
Spark plug is showing the dry sooty deposit - not surprising considering the weak ignition or occasionally missing spark.
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Firing when not their turn indicates you may have the plug wires in the wrong spot.
Firing order is counter clockwise from cylinder 1 where the notch in the dizzy body is. The sticker shows position of cylinders as viewed from above. The arrow points to the front of the car. http://forums.pelicanparts.com/uploa...1428167552.jpg |
I checked the firing order carefully, and they are correctly positioned. Maybe it is arcing over from another's firing time? Or maybe the arc, occurring near my timing light pickup, is causing a strobe at the wrong time?
I got out my big Bentley book and started working through the section. Discovered all my spark plug wires run between 4.01 and 4.09 Kilo-Ohms. They should be 3K! Definitely getting those replaced as soon as they can arrive from PP. Now that I have a real day with real sunlight and time to think, I suspect this problem will be solved soon! I also looked inside the old cap and can see arc trails in various spots. |
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Once it warms up, runs normal, have you tried CHILLING the CDI to see if the problem returns? I don't think that there should be any significant end play, vertical travel, in the distributor shaft. With end play the driven gear tooth angle against the engine's drive gear, would tend to force the shaft upward or downward depending... Still don't like the rotor tip carbon arc being so near the bottom of the cap contact. "springs right back down.." with the engine "cold" how much rotor rotation as it moves from the "up" back to the down position.? Vibrating of the cap may be due to the vertical shaft travel which might also make/break the magnetic field thereby causing extra sparks.. |
OsoMoore,
I was working on my car earlier and a thought occurred to me. An original symptom was bouncing tach. The 6-pin CDI connector has a wire going to the tach in it. If the CDI and coil are stepping up the voltage, then a change in input voltage will result in a change in output voltage. Maybe this is what is common to the two symptoms. |
@wwest - When the engine is cold and idling high, I think it is still doing it's spark thing but I can't hear over the higher idle noise or see any tach activity over the already increased tach from the cold idle. It is when the engine is warm and quiets down to ~900 idle that I can really see the effects. The vertical travel is less than 1 mm - extremely small.
@tirwin - I've re-plugged the 6 pin connector at the CDI. This seems possibly how they are related. I am hoping it will all be clear when these new 3K resistance wires arrive on Wednesday. The worst part of working on your own car is waiting for parts. But I couldn't stomach the extra $50 to get parts two days earlier. |
OsoMoore,
I can completely relate on waiting on parts! I'm in the same boat waiting on a stupid pin to finish the transmission. Looking forward to hearing your results after changing the wires. Did you go with OEM Berus? |
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Got the new wires in, and that didn't solve the problem.
It will run fine sometimes, and then go on its little arcing spree. I'll be watching the wires with my timing light. The spark will be happening at the right position. Then suddenly it starts happening at the intervals when other cylinders should be firing, accompanied by the arcing noise. When watching the coil to dizzy wire with the timing light, it appears to only be firing at one of the six proper positions. I will examine it more carefully tonight. I think it may be time to take apart the distributor, or possibly the CDI box. If I can steal an oscilloscope I can watch the green signal wire, right? Here's what I am thinking with the oscilloscope. If I can confirm the dizzy is sending the correct regular signal to the CDI (green wire), then the dizzy signal circuit is OK and I can blame the CDI or the coil. If the CDI is sending the correctly timed wire to the coil, then the CDI and dizzy signal circuit are OK. And so on down the signal path. Is that right? |
OsoMoore,
You're getting closer. So we know it is inconsistent. Let's talk through other possible causes. Failing CDI: usually gets worse with heat. try getting a can of freeze spray and see if the condition improves when it cools down. That could be why it seems inconsistent. Do you notice that the coil fires properly at cold start and symptoms worsen as the engine warms up? As we discussed the other day this could be the common element to the bouncing tach wire too. Green wire: The green wire is the trigger for the CDI to fire the coil. If it is damaged it could be causing the coil to fire before or after it should. Coil: I don't remember if you had tried a new coil yet. You might want to think about getting one. Worst case you have a spare handy. Distributor: Internals could be in need of refresh. I would try to rule out a couple more things that are simple first. Dizzy rebuilds are not cheap. Any chance a local Pelican could lend you a known good CDI/coil to try? |
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