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Old 09-15-2018, 04:46 PM   #1
AndrewNance
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Default B20 no spark issue

Just finished putting together my 142 with a B20F and HIF6s. Basically stock '71 stuff aside from the head. I cannot seem to get spark past the distributor. The coil wire arcs while cranking when disconnected but I'm not getting anything to the plugs. I've run through what seems like every test in the Haynes manual with no success. I was originally using a Pertronix conversion and swapped back to points/condenser with no change. Resistance across the coil terminals is 4 ohms, and 9k ohms from one terminal to the center. Not sure if that checks out as I searched and found several values to be "correct". I have one engine ground which is a 4ga cable from the bellhousing to frame rail plus the battery ground.

Kind of at a loss here but I know it's going to be something stupid.
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Old 09-15-2018, 05:06 PM   #2
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This should help you. I had the same issue on my last Amazon for a while:

No start issue B20
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Old 09-15-2018, 05:06 PM   #3
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Turned out to be the way I had wired my ignition switch.
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Old 09-15-2018, 05:16 PM   #4
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That's super helpful and I will look into that. I didn't actually change my ignition switch or any of that wiring on this car though. I only removed the engine and replaced it recently. Something else to note is that before I removed it several months ago, I left the key ON for about a month. (I don't remember why but I probably got frustrated and just went inside) I know that's basically the end for a condenser but the points and condenser are both new, plus I had this same issue with the Petronix. Maybe I damaged my ignition switch as well?
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Old 09-15-2018, 05:20 PM   #5
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If you've got spark at the coil wire going into the cap, but no spark at the spark plug wires at the cap, then it has to be either a bad carbon contact inside the cap or a bad rotor.
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Old 09-15-2018, 05:23 PM   #6
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I did reuse my cap and rotor from before but after this issue I replaced them both.
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Old 09-15-2018, 05:55 PM   #7
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I’m getting ~9v at + side of the coil while cranking on a fully charged battery.
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Old 09-15-2018, 05:56 PM   #8
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I don't know about B20s, but normally the distributor rotor lines up with a notch or line on the edge of the distributor when at TDC. If the distributor drive gear is off a tooth, the rotor isn't correctly pointing at a cap tower when the coil fires and the spark can be lost.

Also double check the inside of the cap to make sure that the spring loaded center contact is in good shape.
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Old 09-15-2018, 06:10 PM   #9
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I believe I had the wrong rotor in there so I put the old one back in since it didn’t have many miles on it anyway. I do need to verify timing. Last time I put together a b20 I installed the distributor 180* off. I never fixed it, I just ran the plug wires off too.
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Old 09-17-2018, 10:44 AM   #10
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Many, many moons ago (1985 to be exact), I had the same issue. This was a 68 144 with a 73 B20F transplanted.
After replacing plugs, cap, rotor, points, & condenser, I couldn't get it to fire. I was getting spark, just like you are, from the coil, but nothing to the plugs.
I'm going way back into my memory here, so if it is wrong, it's because I'm getting old. But, there was a phenolic washer of some sort that was not in the correct place which was causing the condenser, I think, to ground on the body of the distributor. Took me at least two days to figure that out at the time.
The moral of this is to make sure that you aren't grounding any components. Again, it was a long, long time ago, but I'm almost positive that was the problem.
Good luck.
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Old 09-17-2018, 12:08 PM   #11
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Quote:
Originally Posted by sksmith View Post
Many, many moons ago (1985 to be exact), I had the same issue. This was a 68 144 with a 73 B20F transplanted.
After replacing plugs, cap, rotor, points, & condenser, I couldn't get it to fire. I was getting spark, just like you are, from the coil, but nothing to the plugs.
I'm going way back into my memory here, so if it is wrong, it's because I'm getting old. But, there was a phenolic washer of some sort that was not in the correct place which was causing the condenser, I think, to ground on the body of the distributor. Took me at least two days to figure that out at the time.
The moral of this is to make sure that you aren't grounding any components. Again, it was a long, long time ago, but I'm almost positive that was the problem.
Good luck.
Steve
+ =1

Make sure the condenser is in there right,

BTDT many moons ago too.
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Old 09-17-2018, 12:23 PM   #12
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But if he's getting sparks out of the coil wire, that's not the issue. That will just cause the coil to not spark since it's always grounded. And likely overheat and possibly explode (small pop, really, not an impressive fireball).

Sparks going into the distributor and not coming out should be fairly easy to diagnose. The spark plug is a gap to jump, there's some resistance there, sparks are more than happy to bypass that if there's an easier alternative.

1) The cap itself - old caps can develop cracks and carbon trails on them that can let the spark shortcircuit to a ground (possible the distributor body).
2) The rotor - it can develop continuity to the metal shaft it sits on. After about 5 - 10K miles of use, the (probably overpowered) ignition system in my PV bored a hole straight down through the rotor to that shaft, at which point the car ran very poorly.
3) The rotor timing - it needs to be pointing at or very near one of the distributor cap terminals when the spark occurs. if that gap is too large the spark won't bother jumping and the energy will dissipate elsewhere. Or it can jump to the wrong terminal. I once installed the sensor wheel on my Crane system wrong. During startup and idle, perfectly fine, the spark occurred close enough to the correct terminal. But rev it up some, get some spark advance going, and the rotor moved further from the correct terminal and it would sputter, cough, backfire, bog, etc.
4) Wires - Ye olden wires of yesteryear were full of big burly metal copper wires, they usually last forever more or less. Newer wires have flexy carbon rubber stuff that probably works better, doesn't last forever. It's possible that the wire's conductor is burned and not conducting. On either end, really.

Also, what does the spark from the coil wire look like? Thin, wispy, pale, blue? Big, fat, red, sizzly looking menace to bystanders? Whatever it is, it should make it through the distributor without much change if everything is working correctly in there, but old coils can lose pep and become very finicky about the plugs and running conditions. That's why people used to worry about plug gaps and plug temperature ranges more than they do now. because a modern ignition system can zap a fouled plug with a massively oversized gap just fine. ZZZaaappp. Wispy pale thin sparks from a tired old coil? Pretty much everything else has to be perfect for that to keep working.
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Old 09-17-2018, 02:02 PM   #13
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Quote:
Originally Posted by bobxyz View Post
If the distributor drive gear is off a tooth, the rotor isn't correctly pointing at a cap tower when the coil fires and the spark can be lost.
This is kind of where I’m at right now. I probably should’ve verified timing before even making this thread but here we are

And I have fought the classic distributor-body-grounding thing before as well. I assumed that wasn’t the issue this time since it wouldn’t fire with the Pertronix either, but I do have the spacers on the distributor with the points/condenser. As far as what kind of spark I’m getting, I didn’t have a helper around so that I could see it closely. The coil seemed to check out but I picked up a new one anyway. Couldn’t hurt to have a spare either way.

We had to cram everything from the yard/porch in the garage for this hurricane so I have to get that stuff back out this evening and take another look.

Last edited by AndrewNance; 09-17-2018 at 02:09 PM..
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Old 09-19-2018, 11:49 PM   #14
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If you're not sure about your timing, finding TDC is easy on these. And with 12 degrees of timing, finding the right amount for the car to start is easy once you have found TDC.

Hopefully that's the issue, that would be nice.
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Old 09-21-2018, 10:18 AM   #15
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I did get it to fire last night. Timing is just way off now. I moved the drive gear a tooth so I’m going to put it back and start from scratch now that I know it’s just a timing issue.

Not sure if I fried the condenser or what since I stopped getting any spark from the coil. I put the Pertronix back in and had spark at the plugs. So it’s nice to know that is working.
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Old 09-21-2018, 08:58 PM   #16
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The 240 distributors have a slot that the hold-down bolt goes through. This limits the rotation, and means that you need to get the drive gear alignment correct. If the B20F distributor has a circular hold-down clamp and can be spun around completely, you can leave the drive gear alone and spin the distributor to statically align it. [It's less confusing for the next mechanic if you can get the drive gear in the proper factory position, but this will work if removing the drive gear is difficult.]

To statically align it, you'll need a test light (preferred) or a multimeter. Rotate the engine by hand until it's at 10deg BTDC on Cyl#1. Turn the ignition on, but don't crank. Connect your test light between ground and the distributor wire terminal on the coil. Now, unclamp the distributor and rotate it counter clockwise until the light just goes on. Go back and forth a few times to get the hang of it.

The light going on means that the points just opened and the coil would have fired. Clamp the distributor down. Now, take off the cap and see which tower the rotor is pointing to. Connect that tower to plug #1 (you're at TDC so that's the plug you want to fire). Now, connect the other plugs in clockwise order: 1-3-4-2. This should get you close enough to start it. Once running, you can fine tune the timing with a timing light.

I'm assuming the 140s are like the 240s and the rotors spin clockwise from the top and the firing order is 1-3-4-2, correct?

[Off topic - in the old air cooled VWs, the #3 cylinder ran hotter because it was cooled by air that had gone through the oil cooler first. To counteract this, VW retarded just the #3 cylinder distributor lobe by 3degrees to lower the cylinder temperature.]
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Old 09-22-2018, 11:13 AM   #17
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Pushrod engines have a distributor (003 in my case) that spins counter-clockwise but the firing order is still 1-3-4-2. I probably turned the distributor body close to 30* to get it to try and start at all but it at least did something. That’s why I want to start from scratch. It only takes a minute to move the drive gear back and start fresh now that I know ignition is at least happening.
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Old 09-24-2018, 10:39 AM   #18
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Okay so we’re good on spark. Cranks and runs for a few seconds and then dies. So that’s progress at least. Letting it sit on the battery charger for a bit while I run some errands.
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Old 09-25-2018, 02:54 PM   #19
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So everything about the carbs seems fine. Floats are set appropriately and not sticking or full of fuel, needles and seats are new and free, throttle shaft bushings are new, mixture screws are two turns down from the bridge. I’ve tried two different oils in the dashpots and both seem to act the same.

I can get the car to crank and run but it won’t idle on its own and too much throttle kills it. It really feels like a carb sync/mixture issue but nothing seems to change much when I fiddle about and it’s hard to do much tuning when it won’t idle on its own. Gonna throw on a new fuel filter just to be sure but the float chambers were full after running it for a minute so that shouldn’t really help me.

The idle isn’t really surging like a loose distributor counterweight might do. It doesn’t rev on its own and die like a big vacuum leak. I obviously have strong enough spark to get it to run. What else should I be checking?
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Old 09-25-2018, 05:28 PM   #20
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Now it may be time to make sure the timing is correct. Too retarded and it won't idle or rev up properly.
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Old 09-26-2018, 09:00 AM   #21
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Did you go full retard ? Never go full retard. Set it at 12 degrees, it will run if timing is your issue.
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Old 09-26-2018, 11:13 AM   #22
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I’ll get back to it next week. I’m not going to worry about driving the car this weekend. I ran into some issues bleeding the brakes last night so I’m going to get that sorted and get the car back on the ground and go from there. Thanks for the tips. I’m sure I’ll be back here.
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