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Chevy HEI problems - What's going on here?

Discussion in 'The Hokey Ass Message Board' started by ahawes, Sep 30, 2011.

  1. ahawes
    Joined: Dec 18, 2004
    Posts: 131


    So on the girlfriends truck w/ 350 occasionally the truck just wont start, no spark. If I pop the distributor cap off and then put it back on immediately it starts right up. What are the possible causes of this? It's the HEI with coil built into the cap...
  2. Mayor of G-Vegas
    Joined: Nov 10, 2010
    Posts: 507

    Mayor of G-Vegas

    Whats the weather like when it won't start? Could be condesation. Is it a factory GM HEI or Aftermarket? - Mayor
  3. 48FordFanatic
    Joined: Feb 26, 2011
    Posts: 1,336

    from Maine

    I bought a new GM HEI . After a few hundred miles it just quit one day on the highway like I turned the ignition off. I went a couple hundred feet and if fired right up. Headed home and it quit three more times . Each time I would stop , put it in park, and it would start right up again. A buddy suggested swapping the module with one I have from a junkyard HEI. It ran ok for a while then started acting up again, I believe this time the symptoms pointed to the pickup . I decided to buy a n HEI from Summit . Paid $99.00 for it, made in China, ( $210 for the GM unit ) and it has been in the car since ( about 8,000 miles) with no problems. I probably shouldn't say it, but so much for Made in the USA.
  4. J&JHotrods
    Joined: Oct 22, 2008
    Posts: 536


    Asking the obvious here, but when was the last time you changed the cap, rotor, wires, etc..? Could be poor contact from the cap to the rotor, and when you pop it back on it fires...just a guess. May be a good time to replace those components as to rule out normal maintenance/tune up items.
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  5. scratch64
    Joined: Sep 29, 2011
    Posts: 3


    Check the brush and spring in the center of the cap that makes contact with the rotor might not be making good connection until you move the cap around might be a good to at least replace rotor and brush
  6. Hackerbilt
    Joined: Aug 13, 2001
    Posts: 6,135


    It's in a Dodge and doesn't feel worthy???? :p:D

    Seriously though....I wonder is there (as mentioned already) an issue with the center button on the cap or the wiper of the rotor button?
    I had one that somehow pitched the button right out! The problem with that wasn't intermittant though. :eek:

    They're usually pretty much foolproof!
  7. mike in tucson
    Joined: Aug 11, 2005
    Posts: 429

    mike in tucson
    from Tucson

    An old garage trick is when someone has a no start, they replace the cap and rotor and charge for a module, cap and rotor.....they wipe the old module off and leave it alone. It seems common that el cheapo rotors arc to the distributor's a really small pinhole leak. Take the cap off and you move the rotor enough to stop the leak for a short while. I have taken a rotor off five times, each time the car started and ran maybe a qtr mile. Then it was at night and my flashlight wasnt strong enough to see the pinhole. Next day, I saw it. Delco rotors are best, Standard brand used to be fine....others are mainly junk made from plastic that floats to china from our trash.
  8. tommyd
    Joined: Dec 10, 2010
    Posts: 10,428

    from South Indy

    What he said, had that happen more than once.
  9. One other common sign of internal arcing, either from the rotor or from the cap/coil, is a fine red dust inside the distributor.

    Older HEIs are notorious for suffering internal arcing from the coil. This often arcs to the centrifugal advance pins, causing them to literally erode away. If you have red "dust" inside the cap, it's happening. Look at the pins and weights very carefully for wear. This will cause erratic timing, because the centrifugal advance is constantly changing and prematurely occurring at idle.

    The cure is to replace the internal coil...and the distributor, if the pins are eroded.

    As Mike notes, use a good rotor and cap; Delco, Standard Blue Streak (the premium Standard line), or Accel. Avoid any rotor stamped "E".

    Another possibility is that you have a loose wire on the module that is being "shook" when you remove and replace the cap.
  10. Check to see if it has the gound strap that goes to the coil from the center terminal. Sometimes people that are not aware will leave this piece out.

  11. Mr48chev
    Joined: Dec 28, 2007
    Posts: 21,327


    I go along with Homespun91 on the loose wire going to the distributor. Especially if the clip that holds it on the distributor has been broken or you are just using a female spade connector in that spot. The wire shades loose and the engine quits, you pull the cap and look and put it back on and push the wire end in tight. I got so I could plug the wire end back in on my 71 until I put the right end on the wire with the clip on it.

    Also the wires on the magnetic pickup have a tendency to break just at the pickup but be connected enough so that the vehicle will run at times. Those wires flex every time the vacuum advance moves the plate.

    Changing the rotor and installing a good quality one wouldn't be a bad idea though and probably won't be wasted money.
  12. ahawes
    Joined: Dec 18, 2004
    Posts: 131


    Thanks for the replies all. This is in a Chevy truck, the Dodge is just sitting now waiting for me to either get working on it or get it sold, I haven't decided which it will be just yet.

    For clarification, the truck is a relatively new acquisition so I've not done any tune-up items to it yet, though these are planned for the near future. The dist is a stock HEI unit. The problem never arises as the truck is driving, it always gets to where it's going and then just wont start again once you go to leave.

    Upon closer inspection the hot wire going into the distributor is missing the clip on the plastic end, is this a junkyard item or can it be sourced elsewhere? I'm going to get the parts to tune the distributor up as seems to be a needed at this point so hopefully this will knock out the problems.
  13. leaded
    Joined: Nov 17, 2005
    Posts: 327

    from Norway

    connections on the wire! Have HEI (external coil)in my inline six, and get bad connection in the wires exactly at the point where they are ging into the distrubitor housing twice. On my, its a connection there, but they are glued in a grommet.
  14. ahawes
    Joined: Dec 18, 2004
    Posts: 131


    Just answered my own question on sourcing the hot wire, Summit has it. I'm an HEI retard, never dealt with GM stuff before now.
  15. Warke
    Joined: Dec 1, 2011
    Posts: 1

    from Newton

    Along these same lines, I have a 1973 Buick Apollo with a chevy 350 in it. It is having some ignition misfire issues and isn't drivable right now. The ground strap is in place from the coil to the cap, but there is no wire in the plug that connects to the cap. Should I run a ground wire from the center pin to the dizzy or manifold?


  16. tooljunkie
    Joined: Oct 18, 2010
    Posts: 209

    from manitoba

    i have seen the rotors blow through on many occasions.
    the cap probably has tracks inside that the arc travels along,but usually the engine cranks like its waaay out of time,and on a damp day its worse.

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