Spark Problem in #1

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lalkie01
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Spark Problem in #1

Post by lalkie01 »

I have a 65 Corsa that began missing. It is getting a good spark when the starter is running but does not have spark when the engine starts. I run a wire from the battery to the positive side of the coil and the same thing happens. I could not see anything wrong with the distributor or cap and the #1 wire looks and tests good. I replaced the #1 spark plug. It did not make a difference. Compression is good. Any suggestions? Larry

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bbodie52
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Re: Spark Problem in #1

Post by bbodie52 »

When the starter solenoid is energized it also applies 12 VDC to the ignition coil positive terminal — effectively bypassing the resistor wire in the wiring harness. Running a wire from the positive battery terminal directly to the coil positive terminal should have the same effect. Did you confirm the presence of 12 VDC at the coil positive terminal with a multimeter when you ran the temporary bypass?

Try disconnecting the brown tachometer wire and the normal wiring harness on the coil positive and negative terminals, leaving only the jumper wire from the battery positive to the coil positive and the coil negative to the ignition points. (Does your distributor include standard ignition points, or do you have a breakerless ignition system from Pertronix, Crane, etc.)?
1965 Corvair Engine Compartment Wiring Diagram (CORRECTED).jpg
Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible

lalkie01
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Re: Spark Problem in #1

Post by lalkie01 »

Stock ignition. 12 volts at positive coil terminal with jumper wire installed. All the other wires have good spark going thru the resistor wire or using the jumper wire. #1 gets a real weak as soon as the engine starts and sometimes no spark at all. I used one of those spark checkers with the clear tube so you can see the spark. Same result. I hate to just start replacing parts without solving the problem. I need to see if I have another spark plug wires and try it. Possibly one terminal on the cap is bad. I have never seen this problem before and I have been working on cars since I was 14. I guess I will learn something new when I find the problem. Larry

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Re: Spark Problem in #1

Post by 66vairguy »

O.K. You have determined the starter ballast by-pass is NOT a problem.

You have determined only one cylinder is an issue, but fine when the engine is starting (turning slowly).

The coil charge period lessens as RPM increases, but it's not an issue with a good ignition system, but does suggest a problem with the #1 cylinder at higher RPM. I'll assume you made sure the spark plug was good at #1.

As you said, try a different spark plug wire (or swap two that are similar lengths to see if the problem moves). Also look into the cap at terminal for #1. Sometimes the contact comes off the spark plug wire and is stuck in the cap. If the spark plug wire and cap terminal are fine then examine the # terminal inside the cap. Also inspect the rotor. You may have an excess gap between the rotor and distributor cap terminal.

If all else fails try another distributor cap and rotor. I've had distributor caps that had no visual defects, yet they were the source of the problem

Finally, rarely I find the distributor cap is "croaked", or it isn't sitting square on the distributor housing when the screws were tightened.

Finally make sure as the rotor turns it isn't hitting an internal wire (points wire from coil, or condenser wire).

Good luck.

lalkie01
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Re: Spark Problem in #1

Post by lalkie01 »

I will look again at all these suggestions. I am probably missing something. Spark plug good on #1. Larry

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bbodie52
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Re: Spark Problem in #1

Post by bbodie52 »

Faulty ignition coil? Poor distributor or breaker plate grounding or faulty ignition points wire between the coil negative terminal and the points that possibly fails or worsens when the vacuum advance moves the breaker plate? Bad condenser?
Point Lead: 1960–69 ALL. Replace that worn wire. C530

Have an Intermittent "miss" in your Corvair? Check the point wires. Old insulation can crack and cause loss of spark power when it happens to short out.

Part number C530: 60-69 DISTRIBUTOR POINT LEAD

Weight: 0 lbs 2 oz
Catalog Page(s): 75,77(11«),77(19)
Price: $ 8.20


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Brad Bodie
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Image 1966 Corvair Corsa Convertible

lalkie01
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Re: Spark Problem in #1

Post by lalkie01 »

I have checked everything listed above with no definite results. The advance plate is bad but does not seem to be grounding. This would affect all the cylinders. I have not seen any damage to wiring. Inside the distributor. I have been planning on replacing the distributor and coil with a stinger unit. I have tested other spark plug wires and they have a stronger spark when the starter is not running and the jumper wire would affect all the spark plugs. Still looking probably something missing probably simple. Larry

66vairguy
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Re: Spark Problem in #1

Post by 66vairguy »

One way to isolate things is swap parts to see if the problem moves. Swap #1 spark plug, swap the #1 plug wire, etc.

BTW - While unusual I have tracked a mis-fire to two spark plug wires not in the in the proper firing order. Check the plug wire locations in the distributor cap.

I took a wait and see position on the Stinger, but at this point the negatives are out weighing the positives. The stock distributor (with the proper knowledge and tools) is easy to rebuild and adding a ground wire to the advance to main plate is easy. The DELCO distributor was well regarded in it's time and will easily go 50K miles. I doubt you'll find anybody to fix/rebuild a Stinger distributor years from now. A quality off the shelf coil for a 1965 Chevy Impala 283c.i. V8 is works great and is easy to purchase.

lalkie01
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Re: Spark Problem in #1

Post by lalkie01 »

I have tried replacing the spark plug and wire and did a cylinder balance test. Still same problem. Weak or no spark on #d1. Larry

66vairguy
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Re: Spark Problem in #1

Post by 66vairguy »

Well this is a long shot --- but inspect the ignition points for pitting. If they look good then get out your feeler gauge and check the points gap with the points rubbing block on the high spot OF EACH CAM LOBE. It's not common, but rarely the points cam wears down.

If points gap is fine, then try another distributor cap AND rotor.

joelsplace
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Re: Spark Problem in #1

Post by joelsplace »

I had a distributor cap once cause an intermittent no spark on one cylinder. It had a carbon track on the inside that was letting that post arc to ground. It was very difficult to see but it was visible on close inspection.
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azdave
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Re: Spark Problem in #1

Post by azdave »

lalkie01 wrote:
Sun Nov 15, 2020 6:36 am
I will look again at all these suggestions. I am probably missing something. Spark plug good on #1. Larry
Are you sayin the engine starts and runs but only #1 is misfiring? You say you can visually see the spark get weak or drop out on #1 when the engine is running? If so, how could it be anything else but the wire or the distributor cap failing?
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66vairguy
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Re: Spark Problem in #1

Post by 66vairguy »

azdave wrote:
Wed Nov 18, 2020 5:09 am
lalkie01 wrote:
Sun Nov 15, 2020 6:36 am
I will look again at all these suggestions. I am probably missing something. Spark plug good on #1. Larry
Are you sayin the engine starts and runs but only #1 is misfiring? You say you can visually see the spark get weak or drop out on #1 when the engine is running? If so, how could it be anything else but the wire or the distributor cap failing?
Seems logical Dave, but a few times I've had folks insist they "checked" everything only to find the points gap (dwell) is off for different reasons. That's why I suggested he check the points gap at EACH lobe. It's unlikely an issue, but easy to check before replacing the cap and rotor.

With five decade old distributors odd things show up. The distributor bushing could be worn, but that usually causes random misfires.

joelsplace
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Re: Spark Problem in #1

Post by joelsplace »

That is true. If the cam or shaft is bent or worn off to one side it could cause only one cylinder to miss. I've never seen it but I think it could happen.
113 Corvairs, 5 Ultravans and counting
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