Crappy idle, misfire on one cylinder.
Anyone one have any thoughts on this?
Plug 2 is not firing. All others look fine. I tried the following to get 2 to work.. 1) plug swap 1 to 2, no change 2) new plug wire, no change 3) tighten up plug, no change 4) change cap, no change 5) change rotor, no change 6) change timing, no variation of timing brings 2 back. 7) change capacitor, no change 8) watched for spark on plug while grounding it. no spark until you hit about 1500 rpm, then spark is there but looks weak. Perhaps my spark is weak all around. Distributor was just rebuild/restored by Jerry MacNeish. I have new plugs, wires, coil, engine harnesses. Totally stumped. |
Maybe you have a faulty coil even though its new... Are the points ok??
Rich |
It seems like the coil is the only thing you have left to change. Maybe swap out the coil for a known good coil? One thing I have found in the past is that most point sets, even the later GM are junk. I was told to give Echlin points a try, I did and really do like the quality of their points. I bought these at NAPA.
Good luck and let us know what you find. |
Do a cylinder compression check. Could be in the valve train, hope not.
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This is what I use on all my cars. As Phil said, today's points are junk.
Your very first tow ride home and you will throw away them points. https://www.lectriclimited.com/break...nversion-85309 Dan |
Was it running fine before the distributor rebuild? Swap distributors would be the first thing I'd do if the previous statement was true. If it cleared up then I would send it back. But FWIW its more than likely the points. Local autoparts store used to have points/condenser kit where the condenser was made onto the point plate and they were great. Never had an issue with them. Blue Streak was the name but I wanna say it was owned by Standard Motor Ignition or Products..
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If the distributor was run on a Sun machine and it tested good you can rule the Dist. out as being the problem, points included.
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Never assume.. You will make an ass out of....... Well you get the point.
As the great President Reagan once said. Trust but verify. |
Change the coil. This sounds like a friend's car last year that suddenly wouldn't run. It had a weak spark and would try to start. The culprit was the coil.
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Would the engine experience the same symptoms if either the lifter got stuck or a valve spring broke?
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I would do a compression test and pull the valve cover. A stuck valve or hole burned in a valve will cause an engine to act this way. Also, by pulling the valve cover it is possible to find a broken rocker arm or a push rod has bent or come out of the bore (usually due to the rocker arm...
Tommy |
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I reread first post. No spark until 1500 rpm then it is still weak? If all parts including coil have been replaced I would just drop in another distributor and see what that does. Tommy |
If one lobe on the distributor cam (for #2 cyl.) was wore down, might prevent spark at low RPM and allow a weak spark at higher RPM when points "bounce"...possibly? Just trying to think what would tie it to only #2 cyl. spark. You might check clearance of points on each distributor cam lobe or at least #2 cyl. and a couple others to see if any variation is apparent?
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If it's on the Corvette, check your grounding.
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Checked the # 2 wire with an ohm meter, and compare with others? Not likely you got two bad ones, but possible.
Next step is kind of a pain, but assuming you have put an ohm meter on the two (2) plug wires you have tried, and they both show good, next step is to pull the distributor, put it in 180 out. Rotate all the wires 180. Start it up. If #3 now has a weak spark, you have pinpointed the distributor as the issue. If #2 still has weak spark, you have eliminated the distributor as the issue. Not likely the coil if it only affects one cylinder. If you don't have a spare distributor laying around, I would be glad to send you a functioning one (won't be curved exactly right for your car, but will at least let you know if it is the distributor. |
This is on my Corvette.
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Have you replaced your spark plugs...not uncommon to have a plug or two go bad.
Dave 67 Nova Boy |
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Check your messages, Tom
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Ok. It was the distributor. I dropped in my old Unilite and it ran great. I have a thought as to what is wrong with it but I will wait until it is looked at. Sending it back to be checked out.
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If one lobe is worn it would show a late spark on that lobe. |
True..
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I think the tester would/should show it, but isolated to #2 cyl. only, and it appears to be in the distributor, just trying to think what it might be. Distributor cam lobe seems logical?
Interesting puzzle... Be glad to see the findings. |
Shipped it back for analysis and repair. I'm interested to find out myself. In the meantime, running great with the Mallory Unilite.
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Ok. So this was the root cause. Bent. Not sure how or when it happened. All I can say is that I returned it and he fixed it and got it back to me quick. I installed it today and drove it and all is well so far.
http://img.photobucket.com/albums/v3...DDC378BBD7.jpg |
Thanks for follow up. Many times no one lets one know the outcome. Glad it is fixed as I am sure you are, as well.
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your my hero Eddie.
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soon, the top plate is bent? how might that effect it?
i can see the rotor contact might not be close to the tab in the cap, but was it off that much? appreciate the thoughts? |
Agree, Would think it would be off the same for every contact in the cap?
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