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One for the books Went to look at a 28 Sport coupe 3 weeks ago, it had been sitting for a couple of months. The owners son got it running, and it sounded fine. A week later I go with the trailer to pick it up, and it will not start. When it finally would start, it smoked and ran terrible then died. We cleaned the points, cleaned the plugs, won't start. Pulled the coil wire, hot Spark, it was getting gas, still won't start. Checked the cap and rotor looked fine, left the plug wires off of the distributor with a gap of about 1/8 inch, starts up and runs ! Now there is spark jumping from the distributor to the wires, then the plugs would fire ! Unfortunately, the owners son got a picture of it, but I didn't. So we put in a new set of plugs and it started fine and ran great. Has anyone ever heard of this happening? None of us could believe it, and I still get a laugh when I think of it.
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Re: One for the books Quote:
Bill |
Re: One for the books I had something like that happen to me when I replaced my points and condenser. I got a spark from the cable that goes to the firewall, it was shorting on the head. Either I let the wire on the bottom of the distributor plate ground out, or just had to replace the cap and rotor. Not sure.
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Re: One for the books Putting some gap between the plug and plug wire causes the voltage to build up higher. This will burn through fouled plugs. It also does this at a cost in time. It effectively trades a delay in the spark for higher voltage. You do not get something for nothing.
At the flea markets there are these guys selling a spark enhancer. They have been around since the 40's. They make a gap to force the coil to build more voltage before current can flow. Inside there are some graphite disks if I remember correctly. BTW, those guys get real upset when you point out the physics and why they are not good. |
Re: One for the books This is a very common problem with cold starts and little run time. In the late 70's I saw a lot of this with new car deliveries off the transport truck. And this was with the new electronic ignition.:D
It's even a worse problem with 2 stoke engines with oil in the gas. My neighbor asked for my help to get his weed whip started, so I removed the plug and got the electrodes red hot with a propane torch. He was surprised when it started on the first pull after the heating. I've had to let some engines run for a good 30 minutes with the coil wire jumping a 1/4" gap before I could push the wire back in without the plug misfiring. One bit of warning.:eek: In the late 70's we had a new Chevy running, fresh off the transport and a couple plugs were misfiring. The catalytic converter got so hot that the carpet inside the car started on fire. We got the fire out with no damage other than having to pull the seats and install new carpet.:) |
Re: One for the books My old 8N fouls plugs, I don't run it often enough to bother to fix it, it always starts, don't smoke much, but every so many hours of cumulative run time it will start to foul and will be all black and "fuzzy" with soot. I unplug the wires from the distributor, and just set them back on where the boots are just touching the top of the cap, and fire it up. After 4 or 5 minutes it's running good again. I can get away with this 2 or 3 times over several months before I have replace them.
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Re: One for the books Kevin, about the delay in spark- Using current science regarding spark propagation between charged points in the atmosphere I come up with an added delay of 0.00000037 seconds*(note 1) for an added 0.050" gap, likely a larger gap than one of those 'enhancer' thingies. I could punch more calculator keys and figure the delay in degrees at 2500 rpm, but with all those zeros I don't think it will add up to squat. Of course killing the coil is another story and reason enough not to do it long-term.
*Assuming a theoretical perfect air gap of zero capacitance. If there are two graphite plates as you state, the delay to breakdown will be longer as the plates charge, causing the coil voltage to rise even higher followed by a slightly higher amperage arc. Possibly the "secret" to their functionality? Anybody have a dizzy machine with a scope and one of those 'enhancers' handy? Both coil voltage and any readable added propagation delay would be interesting to see. |
Re: One for the books Spark intensifiers have been around sense the 1910's or 1920's.
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Re: One for the books Back in the seventie's an old time mechanic friend of mine gave me one of the spark intensifiers, I put it on an old 6cyl chev. And drove around with it for a summer, then took it off. I couldn't tell any difference, theoretically the way it introduces a secondary gap may have some benefit.
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Re: One for the books I knew I'd get the right answer here, I've never seen it before. When we hooked the wires back on to the distributor though, it still wouldn't start. Also we put a propane torch on the plugs, and that didn't help either. We had to put in new plugs in before it would run right.
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Re: One for the books I love it when I learn something new.
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Re: One for the books I have used those spark enhancers for years.
They DO work and are not snake oil. They are old history now with computerised cars but they were great in their time. I fitted them to others cars and told them to drive it and tell me what they think. I did NOT tell them what I did. In all cases, they noticed a slight improvement. It was noticeable in pulling power, when a car can just not quite get up a hill without changing, fit the gizmo and it gets up without changing. I did some zero to 60 times, but could not get anything to note in faster times on the flat, just pulling power. And I am very much a skeptic on most things. |
Re: One for the books one tip; Run the engine at night and look for wires shorting out.
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Re: One for the books I'm running the stock setup, but it has V8 points and condencer. Brass wires, stock distributor body, 6V. That's why it was so easy to gap the wires at the distributor. And your right 700rpm, there's always something new to learn here.
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Re: One for the books My father told me that they used buttons as spark intensifiers.
Chet |
Re: One for the books So if I understand this right, one takes the strap off of the distributor just about a 1/4" or so and it should run? This will 'intensify' the spark and help clean the plug off-used in short duration of course. Or am I missing some part of the picture.
Mike |
Re: Spark Intensifier Explained |
Re: One for the books Quote:
Bill |
Re: One for the books Sooo, why not just file the rotor and create a larger gap there?
Just my WAG at the question JB |
Re: One for the books This happens often when you sand blast the plugs. You remove all the glaze from the porcelain and plug shorts from gas saturation. 30's and 40's this was common with rebuilt plugs from Western Auto and other suppliers. Would drive people crazy after changing the plugs, no start. Clinton
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