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Ignition problem

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70herald

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I got the engine in the herald to run earlier last week, but I have some ignition problems
It was running, but missing fairly well, but missing on a frequent basis. Since the distributor shaft was wobbly, I got a hold of a different dizzy, with a much better shaft/ bearing, cleaned it up, put in new points/condenser etc. then I couldn't get it to run at all. Eventually, I figured out that the drive dog was on the opposite direction vs. the original dizzy so I swapped around all the cables, and now it at least sputters.
The plugs were somewhat wet from cranking the engine and black from having run way to rich earlier on, could this really be enough to cause sparking problems? Other than swapping the coil is there anyway to tell if it is generating enough voltage?
 
70herald said:
The plugs were somewhat wet from cranking the engine and black from having run way to rich earlier on, could this really be enough to cause sparking problems? Other than swapping the coil is there anyway to tell if it is generating enough voltage?
Click to expand...
Are you sure your valves are ok? I have had problems in the past thinking it was ignition when it has been top end. Particularly when the engine is cold.

To check coil discharge, you might try one of these (jpeg attached). Basically you connect a plug-wire to it and crank the engine. It has a sliding adjustable scale at the discharge end and you measure the length of the spark generated, giving you some idea of the secondary strength of the coil. Lisle makes this particular one, and they sell for between $5-10 here.
 

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guzzul said:
Are you sure your valves are ok? I have had problems in the past thinking it was ignition when it has been top end. Particularly when the engine is cold.

To check coil discharge, you might try one of these (jpeg attached). Basically you connect a plug-wire to it and crank the engine. It has a sliding adjustable scale at the discharge end and you measure the length of the spark generated, giving you some idea of the secondary strength of the coil. Lisle makes this particular one, and they sell for between $5-10 here.
Click to expand...

The engine only has about 45 minutes of running time after a very complete rebuild. Pretty much EVERYTHING came apart.
When I put the carb back together I must have turned the jet adjusting nut the wrong way, since it was running very rich (the neighbors came by to complain that I was stinking them out!)
I had it running fairly well however, with the original distributor it was missing. (I could hear it and see the missing sparks at idle with the timing light) Since the original was somewhat sloppy, I swapped it for a different unit with a much better bearing (no wobble on the main shaft) Before I swapped the distributor, I had it idling nicely at ~850 rpm, nice and quite, the only problem was that it was missing about 1 in 5 or so ignitions based on missing flashes of the timing light.
After I put the new distributor on, it didn't start at all, at which point I discovered that the drive dog was opposite the position of the original. No big deal, just swap the wires around. Now it starts, but sounds absolutely terrible.
All of the cylinders seem to be firing but very weakly.
 
Sounds like you're right to start walking through the ignition circuit. I would check both primary and secondary circuits.

The other thing you could try at the high voltage end are those test-lights you attach between the plug and plug-wire. The colour or intensity of the light should give you an idea of whether the coil is putting out a good spark. I would consider one in the coil-to-cap wire also to see what's coming directly out of the coil.
 
Andrew Mace said:
I hate to say this (especially since I've done it myself), but are you absolutely SURE about the wires being on the correct plugs?
Click to expand...

Well if I say I am sure, I am going to find them all in the wrong location! Seriously, after swapping the dizzy, they were all in the wrong location, since the drive was on in the opposite direction. I turned the engine to # 1 on TDC, put the #1 plug wire in place and then just hooked up wires up 1,3,4,2 in ccw order. I doubt I would have gotten anything to work if they were off by 1 position?

The chance of finding a simple spark tester here is rather poor (no culture of DIY auto mechanics) I guess I will put this on my list of thing to buy next time I am in the States.
In the mean time, I am going to clean all the plugs and see if that helps, and hopefully find a new coil. Everything else in the circuit is new.
 
70herald said:
I doubt I would have gotten anything to work if they were off by 1 position?
Click to expand...
No, probably not. But if you have accidentally swapped, say, 3 and 4, it likely will run...but badly. (PLEASE don't ask me how I know this; I'll only say that I have both diagnosed...and CREATED...such a problem in my time!)
 
It RUNS! YEAH /bcforum/images/%%GRAEMLIN_URL%%/banana.gif

Really weird problem. turns out the plugs had so much carbon build up / wet from gasoline from trying to get it started that they were shorting out! One plug had ~900 ohms to ground, another plug 120 ohms, so no Spark at all. I picked up a nice new set of NGK plugs popped them in and it started right up. Played around with the timing and it sounds really sweet, nice quite, no misses, set the idle at 900 and it is nice and smooth. Temp stayed at a steady 170F at the hot side of the water pump.
Now just a few little issues and off for inspection.
 
/bcforum/images/%%GRAEMLIN_URL%%/banana.gif /bcforum/images/%%GRAEMLIN_URL%%/thirsty.gif /bcforum/images/%%GRAEMLIN_URL%%/cowboy.gif
 
My father-in-law vintage races his Formula-Vee. More than once he's carbon fouled the plugs due to carb float problems. Each time he tries to blame the problem on something else and is hesitant to even pull the plugs to check.

I'm glad you found the problem and that it's running well.
 
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