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HEI coil issue?

Discussion in 'Off Topic Hot Rods & Customs' started by 63401nailhead, Feb 25, 2026.

  1. 19Eddy30
    Joined: Mar 27, 2011
    Posts: 4,400

    19Eddy30
    Member
    from VA

    It does , just not a coil wire
    The spring & the carbon / graphite pin under coil to rotor :cool:
    Op said installed another distributor,
    Still no spark ,
    I would say ground or No 12 volt in crank .
    Does the rotor turn , as in when you pull cap in different spot after cranking ?
    If not is it possibly a really unusual issue broken cam teeth ?
     
  2. 4NUTZ
    Joined: Apr 4, 2008
    Posts: 338

    4NUTZ
    ALLIANCE MEMBER

    Okay so there is power at the distributor when cranking. It’s actually drops from 12v to about 10v while cranking. So what is that telling me?

    Next going to remove the distributor cap and try cranking it again to see if the rotor is turning. Do I disconnect power to the distibutor when doing that, or leave the pink wire connected?
     
    Kerrynzl likes this.
  3. Mike Lawless
    Joined: Sep 20, 2021
    Posts: 779

    Mike Lawless

    You don't need to disconnect anything. You really only need to crank it long enough to see if the rotater actually rotates
     
  4. 4NUTZ
    Joined: Apr 4, 2008
    Posts: 338

    4NUTZ
    ALLIANCE MEMBER

    Okay just checked and the distributor/rotor is turning when I crank the engine with the distributor cap removed.
     
  5. Kerrynzl
    Joined: Jun 20, 2010
    Posts: 3,608

    Kerrynzl
    Member

    Have you actually tested the ignition with another sparkplug grounded to the block ???
     
  6. 19Eddy30
    Joined: Mar 27, 2011
    Posts: 4,400

    19Eddy30
    Member
    from VA

    I think I mentioned in past,
    I would bench test & not move to vehicle until I was able to get spark on bench ,a Few leads, batt , plug ,
    test light, voltage meter. .
    You can spin shaft with hand/ fingers ,
    Wants or If spark on bench ,
    Then you know issue with wiring on vehicle.
     
  7. Moriarity
    Joined: Apr 11, 2001
    Posts: 38,982

    Moriarity
    SUPER MODERATOR
    Staff Member

    Man, these threads make me love my Ignition point setups more and more....
     
  8. 19Eddy30
    Joined: Mar 27, 2011
    Posts: 4,400

    19Eddy30
    Member
    from VA

    Points can be bench tested just as ease ,
    Over the years there's been several times I went to go look at a engine a long blocks with a battery starter HEI in hand and a can of starting fluid and tape to start an engine. Tape for no carb , tape intake up
    Spray with a controlled vacuum leak run off can.
    Also Times used a Mag
     
  9. gene-koning
    Joined: Oct 28, 2016
    Posts: 6,211

    gene-koning
    Member

    If there is power to the distributor while cranking and while the key on, and all the parts in the system are still good, new and good (which is no longer absolute truth) or has been replaced with good parts, there should be spark to a good spark plug that has a good plug wire connected to good cap plug wire post and the plug has a good ground positioned so you can see the spark.

    Understand that you are only checking the spark at that one plug and wire, are you cranking the motor long enough to rotate through the complete firing order at least a few times? That spark is going to be a quick snap, then it will be gone until the next time you spin through the firing order and get back to that one plug and wire again.

    You have stated that the rotor is turning while the motor is cranking, and you have power to the distributor while cranking and while the key is turned on. The only variables left in the system to have a spark is the distributor cap, the rotor, the plug wire you are using, and the plug with its ground.

    If there in no spark to the plug using this test procedure, something in the system is still defective. Everything needed to create a spark with the HEI system while the rotor turns is in that distributor, except the plug, the plug wire, the condition of the distributor cap where that plug wire is connected to, the rotor condition, and the plug ground. All of these things have been tested except the plug and the wire. The only other quick option would be to use a different plug wire at a different location on the cap and a different plug that still needs a good ground.

    With power to the distributor and a rotating rotor, the HEI system will deliver a spark to a good plug, plug wire, and plug ground. No spark means something with in the HEI distributor is defective.

    Even if the timing chain was out of time with the cam and compression, there should still be spark as long as the power to the distributor is present and the rotor is turning. The spark would just be delivered to the cylinder at the wrong time. That could effect the motor running, but not the spark.
     
    Last edited: Mar 22, 2026 at 1:03 AM
    firstinsteele and 19Eddy30 like this.
  10. I have my doubts that points would work in this case.

    Ben
     
  11. gene-koning
    Joined: Oct 28, 2016
    Posts: 6,211

    gene-koning
    Member

    I did mention a timing chain in post #12. Others have mentioned a timing chain as well.
    I had to look back, and sure enough the OP has never said if he checked for a spark or not. He was told how to do so several times, I suppose we have all presumed he did check for a spark.

    He may have bought a lot of ignition parts when he should have been replacing a timing chain & gears.
     
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  12. Moriarity
    Joined: Apr 11, 2001
    Posts: 38,982

    Moriarity
    SUPER MODERATOR
    Staff Member

    OK @4NUTZ have you actually checked for spark by putting a plug in one of the wires and watching it for spark while you crank it?
     
    210superair likes this.
  13. 1946caddy
    Joined: Dec 18, 2013
    Posts: 2,482

    1946caddy
    ALLIANCE MEMBER
    from washington

    19Eddy30 likes this.
  14. TA DAD
    Joined: Mar 2, 2014
    Posts: 1,625

    TA DAD
    Member
    from NC

    You can bench test a GM HEI dist by putting 12v to the cap and grounding the body and if all is in working order rotate the shaft and it will be clicking in the cap. The clicking you hear is the spark jumping in the cap.
     
  15. 4NUTZ
    Joined: Apr 4, 2008
    Posts: 338

    4NUTZ
    ALLIANCE MEMBER

    Sorry guys I thought I mentioned yes did check for spark. I used one of those tester tool things that you plug between the wire and the plug. Got a red spark on each.
     
  16. Moriarity
    Joined: Apr 11, 2001
    Posts: 38,982

    Moriarity
    SUPER MODERATOR
    Staff Member

    so you do have spark then??
     
  17. 4NUTZ
    Joined: Apr 4, 2008
    Posts: 338

    4NUTZ
    ALLIANCE MEMBER

    Yeah the tool lit up bright red in the center
     
  18. Moriarity
    Joined: Apr 11, 2001
    Posts: 38,982

    Moriarity
    SUPER MODERATOR
    Staff Member

    if that is the case then you do not have an ignition problem and possibly a jumped timing chain
     
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  19. 4NUTZ
    Joined: Apr 4, 2008
    Posts: 338

    4NUTZ
    ALLIANCE MEMBER

    Will try to take the timing cover off tomorrow and inspect. Although it might not be obvious unless a tooth is missing, which I guess could happen especially if it’s the factory nylon gears.

    What’s interesting though is that it drove fine all day all the way up until I pulled into the garage and parked it for the night. When would it have skipped?
     
  20. Moriarity
    Joined: Apr 11, 2001
    Posts: 38,982

    Moriarity
    SUPER MODERATOR
    Staff Member

    they skip when you try to start it.

    DO NOT TAKE THE TIMING COVER OFF
    Do this instead. remove the number 1 spark plug. with your finger in the hole bump the starter until you feel compression. turn the engine by hand (same direction) until the timing marks line up. remove the dist cap and see if the rotor is pointing where the number 1 wire is
     
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  21. fastcar1953
    Joined: Oct 23, 2009
    Posts: 4,280

    fastcar1953
    Member

    Factory fiber gears would strip out. The rotor wouldn't turn.
    Steel might break a tooth and jump time. The engine should still fire and backfire.
    He has spark at plugs but not firing at all seems strange.
     
    Moriarity likes this.
  22. fastcar1953
    Joined: Oct 23, 2009
    Posts: 4,280

    fastcar1953
    Member

    Check compression?
    Pour gas down carb? accelerator pump bad?
    How fast does it crank over?
     
    Moriarity likes this.
  23. 210superair
    Joined: Jun 23, 2020
    Posts: 2,280

    210superair
    Member
    from Michigan

    You said definitely getting gas to the carb. Did you give it a squirt of starting fluid just to be sure it's not a fuel issue? Gas to the carb and gas thru the carb experiences can and will vary.... And it'll take five seconds. I always attack the simplest things first. Occam's razor...

    If it still doesn't fire, I'd do what Moriarty said...
     
    SS327 likes this.
  24. gene-koning
    Joined: Oct 28, 2016
    Posts: 6,211

    gene-koning
    Member

    The problem here is that if he has changed the module inside the distributor, and he has replaced the distributor with another, he may well not have the #1 plug anywhere near where its suppose to be.
    And if the timing chain has jumped 2 teeth, or the oil has been washed off the cylinder walls, the compression could be low enough it may be hard to detect while cranking over.

    At this point, the starting place may be a compression test on every cylinder, with all the spark plugs removed. That will at least give us an idea if the timing chain is close. If the compression is decent and consistent, he can proceed.

    He needs to bring #1 up on compression, line up the timing marks and make sure the distributor is rotated correctly to ***ure the rotor is pointing towards the wire going to the #1 cylinder. Then he has to make sure the rest of the wires are going to the correct cylinders in the firing order, in the proper direction.

    Then before he puts the plugs back in, he probably should squirt a bit of motor oil into each cylinder and spin the motor over a few times to be sure the oil has not been washed of the cylinder walls. Then he can reinstall the plugs and replace the wires. At that point, he can try to start the motor, adjust the timing, and see how the motor runs.

    There could still be a timing chain issue, if the motor is really weak, or still won't start, the timing chain and gears will be the next step.
     
  25. On Feb 25 ...
    On Mar 23 ...

    I am completely confused here. On Feb 25th (at the beginning of this journey) you mention the need to check for spark. You then go on to tell us you tested or replaced this, that and the other thing (in your ignition system) over the course of the next month. On Mar 23rd after some prodding, you finally enlighten us to the fact that you had (at some point we still aren't clear on) indeed checked for and verified you were getting spark at the plugs. If you verified spark on or about Feb 25th, what exactly is it you have been looking for over the past month?

    Did you ALWAYS have spark or, during the course of your "throwing parts at it" did you once again find your lost spark?

    I'll say it once again and this is my own personal experience (I posted this previously but deleted it once it became obvious you hadn't read my post) ... I owned and daily drove a 1980 Ford 200 6cyl. Ran great all day, every day until I parked it overnight and it failed to start the next morning (sound familiar?). Checked for fuel ... yup, fuel is present. Checked for spark ... yup, spark is present, verified air can reach carb ... yup, no restrictions. I then determined my issue must be spark timing as I had everything else needed to run. Turns out my timing chain had, between turning off the car one night and attempting to start it the next morning, jumped a tooth or two. NO STRIPPED GEARS, NO MISSING TEETH, just a chain loose enough to jump out of time. Tossed in a new chain and gears and it ran perfectly for years.

    I am not saying the timing chain IS your issue but it was mine and our symptoms are identical. Since it appears you DO have spark and fuel, I'd suggest you STOP searching for (more or better?) spark and start looking elsewhere ...

    The big question here is this ... did you ALWAYS have spark at the plugs or did you regain spark at the plugs after throwing parts at it?

    If you always had spark, I'd suggest spark is NOT your problem. If you initially didn't have spark but now do, that suggests you solved the lack of spark problem but in doing so, have caused a timing issue, possibly when you swapped in the different distributor.

    Best of luck, I'll be watching from the sidelines from here on out :)
     
    Last edited: Mar 25, 2026 at 8:59 AM
  26. MAD MIKE
    Joined: Aug 1, 2009
    Posts: 989

    MAD MIKE
    Member
    from 94577

    Are we talking about a bulb indicator, or actual spark color?

    Red/orange spark is weak.
    It should be blue/white.

    Some cheaper HEI modules dont like to be left ON without running, they'll cook themselves.

    I didnt read the whole thread, lazy on my part, have you verified that there is a solid ground and bond of the engine block and distributor?
     

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