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Thread: Ignition Problems

  1. #1
    Member Nemo von Klepper's Avatar
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    Ignition Problems

    I seem to be making some progress on my basketcase CJ3B, aka Frankenjeep.

    The solenoid was bad, so I changed that to our host's solenoid. This is when I discovered that the wiring between the battery, ammeter, alternator, starter switch, coil and solenoid was not to spec. The previous owner had a four post solenoid on the firewall and for whatever reason the wiring was somewhat cobbled together and nothing matched at the starter switch. I also had extra wires from the coil and alternator running to the fourth post on the old solenoid, labeled "1". I ripped out all of this previous wiring and ran it back to factory spec. That seems to have fixed the solenoid problem.

    Now it seems I have an ignition timing problem. There's no mark on the flywheel, so I have to guess. I have the firing order correct: from the distributor: counter-clockwise 1-3-4-2, and on the engine, fan to firewall: 1-2-3-4.

    It's starting, but it's running rough and backfiring into the exhaust. I played with the distributor position, but even in an optimum position it backfires.

    I checked the plugs and they seem to be getting spark--though I understand they should be blue, not white-yellowish orange. The spark plug and point gaps seem to be right.

    What's my next best step?

    The coil is going to need to be replaced. It melted down/exploded while I was checking my wires and spark plugs. I suspect this was because I left the ignition switch in "drive" while I was doing this, but as I mentioned above, I also recently rewired the coil. The hot side is coming from the ignition switch post labeled "ignition". The ground is direct to the distributor.

    Can a coil melt/explode if the key is left in drive position?

  2. #2
    Super Moderator LarrBeard's Avatar
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    Quote Originally Posted by Nemo von Klepper View Post
    I seem to be making some progress on my basketcase CJ3B, aka Frankenjeep.

    It's starting, but it's running rough and backfiring into the exhaust. I played with the distributor position, but even in an optimum position it backfires.

    I checked the plugs and they seem to be getting spark--though I understand they should be blue, not white-yellowish orange. The spark plug and point gaps seem to be right.

    What's my next best step?

    Can a coil melt/explode if the key is left in drive position?
    Running, even rough, is a big step. It says that things are all there, you just need to get them working in sync.

    A. Next Step? Backfiring through the exhaust tends to indicate that an exhaust valve is still open when the cylinder fires. Just a WAG from NE IN would be that you have a valve sticking open. Not uncommon with engines that have sat around for a while. Exhaust valves get hot gasses going past them that can warp the stem and accumulate deposits. You may have to pull the head and valves if it doesn't clear up after it runs for a while. There isn't a good way to try to clean the stems from outside he engine...

    B. Can a coil melt/explode ...? Spark should be a blue spark. White/yellow-orange is a low intensity "lazy" spark. The usual suspects are points and condenser. Maybe plug wires, but if every plug is lazy, probably not wires unless all of them are beyond their use-by date. The coil, if it's still the damaged one, is suspect.

    Many coils are oil filled. I could see one overheating and exploding , especially if:

    (1) The ignition is left on for a long time with the points closed. If I have to do work with the ignition ON, I bump the engine until I see the ammeter go to 0 (center) showing that the points are open.

    (2) In all of the Franken-work, an ignition dropping resistor got left out of the circuit. Many 12-volt conversions as well as just 12-volt systems used a 6-volt coil with a dropping resistor. The dropping resistor was bypassed by the ignition switch during start to give a hotter spark and connected during run conditions.

    A 12-volt system with a 6-volt coil and no resistor could get very hot, overheat and "BLOOIE".

    Let us know how things go with Frank ...

  3. #3
    Super Moderator gmwillys's Avatar
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    I would first look at the spark plug wires. High resistance on a plug or coil wire will cause your coil to overload and melt. Standard resistance should be around .5 ohms, measured by a meter at both ends of the wire. High resistance can cause the spark color you are seeing.

    Points are usually a victim of the ignition being left on for a long period of time. The contacts will be the point to where they fail. A coil could be damaged with the ignition left on, but I would look at everything else before condemning the coil first.

    A quick rule of thumb when timing, when in doubt, pull #1 plug, (closest to the fan) and hold your thumb over the hole. Turn the engine over by hand until you feel the cylinder building compression at your thumb. Slowly continue to turn the engine until the point that you no longer feel the compression, (TDC). Then check your rotor on your distributor. It should be close to #1 position on the cap. Firing order is 1-3-4-2, as you stated.
    Last edited by gmwillys; 11-26-2018 at 12:01 PM.

  4. #4
    Member Nemo von Klepper's Avatar
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    Thanks. I was wondering if the points in contact wasn’t an issue for the coil. It was essentially a textbook setup. The coil came out of my classic SAAB 900 parts car. It was fine, but my Saab shop manual warns about leaving the ignition switch in drive position for lengthy periods. I have another 12V coil that might be okay.

    I like the spark plug wire idea. Before I read this post I ordered a generic wire separator with hopes that isolating the wires will help ensure from grounding faults.

    I like the alternative method for finding TDC, thanks!

  5. #5
    Super Moderator LarrBeard's Avatar
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    Spark Plug Wires

    Quote Originally Posted by Nemo von Klepper View Post
    I like the spark plug wire idea. Before I read this post I ordered a generic wire separator with hopes that isolating the wires will help ensure from grounding faults.
    Just a note; if someone has slipped a set of noise suppression wires into the mix, they can read a high resistance. Metal wires should read the half-ohm or so.

    Yeah, nothing is ever simple .....

    Sea Story Time:

    On the '48 with the F-134, we fought a balky, stalling rough running engine for almost a month. Keep in mind that between the two of us, our combined ages were over 125 years. Finally we called on an "old guy" (so you have an idea of what we consider "old") and his immediate answer was "You have a bad condenser".

    We protested, "But, it is a brand new distributor".

    Being an "old guy" his reply was "Do you want to argue or do you want the d$#m thing to run? Replace the condenser".

    We took the distributor apart - and here is what we found. We replaced the condenser like he told us.

    It's run like a champ ever since.
    Attached Images Attached Images

  6. #6
    Super Moderator gmwillys's Avatar
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    Never argue with experience. When they tell you to go over to the wall of special tools and grab a exhaust manifold stretcher, just do it, and don't call B.S. The experienced guy will knock you in the head with it. True story, I thought I knew more than I did. The tool was an actual Ford tractor service tool that expanded the cast manifold enough to fit over the studs.

    Good call on the wires. I didn't add resistance wires to the equation, nor the condenser.

  7. #7
    Super Moderator LarrBeard's Avatar
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    Ignition Problem Supervision

    [QUOTE=gmwillys;6438

    Good call on the wires. I didn't add resistance wires to the equation, nor the condenser.[/QUOTE]

    Oh yeah - go send the new guy in the shop for a bucket of steam to clean the fallopian tube in the radar, or a fathom of water line to tie down for heavy weather .... That's why it takes two of us standing round with our hands in our pockets watching the one guy working.

  8. #8
    Super Moderator gmwillys's Avatar
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    Or our favorite, send the new guy after the 1D10T form. He will be gone for hours looking.

  9. #9
    Super Moderator LarrBeard's Avatar
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    Sea story

    Quote Originally Posted by gmwillys View Post
    Or our favorite, send the new guy after the 1D10T form. He will be gone for hours looking.
    Things to tell new Con officers; ( Con officer drives the ship):

    "Sir, CIC has a radar contact, an inbound B1RD on a collision course. What evasive action do you recommend?"

    No sympathy .....

  10. #10
    Member Nemo von Klepper's Avatar
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    Quote Originally Posted by LarrBeard View Post

    "...an inbound B1RD on a collision course. What evasive action do you recommend?"...
    Fire on target?

    There's a chance the wires are beyond their optimum performance. They are the same wires that were in it when it last ran 9 years ago; same with the condenser.
    I've been flying low to keep off my wife's spending radar. Even though I'm the CFO around here, she can smell cash burning. So I've been applying a healthy application of Ockham's Razor and only working on the obvious needs and the most probable causes. Wires, condenser, etc. are getting close to the top of that list.

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