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HEI question

Discussion in 'The Garage' started by Blazer1AB, Nov 3, 2005.

  1. Blazer1AB

    Blazer1AB Registered Member

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    Correct me if im wrong, but my understanding is that there is two different types of HEI that were put in our trucks correct? One with 4-prong ignition module and one with 5-prong ignition module (Electronic Spark Control). Are these basically the same except the system with the 4-prong module doesn't have an extra connector with wires running to a little "computer"? or am I way off base. Next question: if my blazer has the Electronic spark control, can I switch it out to the other distributor?

    I really wanna figure out my ignition problem and the only thing really left is that electronic spark control. The whole distributor was new and the distributor wires are all good and it still doesn't get spark SOMETIMES. It has to be either that or the ignition switch, but would it cause this intermittent problem, and where is it at? I am in desperate need of help!!!
     
  2. readymix

    readymix 3/4 ton status

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    Post up a few details about your truck and we can help.
    year
    model
    what have you replaced
    T/S so far?

    There are 2 different distros. Large and small. Large has the coil in cap. Small is remote coil. The ignition modules are different between the two.

    One thing i have seen cause issues occasionally is the way the PU coil plugs into the EST. Look closely and it might be plugged wrong. You can plug it in and hear it click, but the pins might not be centered in the socket.
     
  3. Blazer1AB

    Blazer1AB Registered Member

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    1983 K-5 (orginally 305, but replaced with jasper crate 350) about 30k on this motor

    What happens is that the truck will run fine, and all of the sudden out of the blue it wont start. It cranks, but gets no fire. All the times that it does this, it IS getting power to the distributor. Its the 5-pin ignition module with the coil on the cap. First I replaced the cap, coil, ignition module, and rotor. Thought I fixed the problem, but it did it again. My thoughts were that it was the pickup coil, and since the only thing that hadn't been replaced by the previous owner was the distributor, I put a new one in. So it had new everything, except plugs and plug wires (which dont look in bad shape). After I put the distributor in, set timing and was playing with carb. It died, and the same problem was there again- crank but no spark. I was pissed so i packed it up, went out the next day and after a couple of tries it fired up. Any thoughts??

    Also one other thing- when it does this problem, sometimes when you try to start it and then you turn the key all the way off, it seems like it spins the motor over a little- even if you wait a few seconds and then turn the key off. But it has yet to do this with the computer unplugged....(sorry if that is a bad description)
     
  4. loafer

    loafer 1/2 ton status

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    Check out the attached Word file.
     
  5. loafer

    loafer 1/2 ton status

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    Nevermind...I can't attach word files for some reason :doah:
     
  6. Blazer1AB

    Blazer1AB Registered Member

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    ANYBODY? This has had to happen to someone! Is there a way to bypass the computer someway? Since the motor doesn't have the electronic carb on it or anything original.
     
  7. cwn anwyn

    cwn anwyn 1/2 ton status Premium Member

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    It might be your ignition switch. I'm not sure.:confused: I did the same switch a couple of years ago. Swapped in a 350 inplace of a 305 in my 84 K5. I originally left the ESC and distributor alone. I just recently decided to get rid of the esc. Here is a link to what I started with, and there are some threads on here about swapping in a non ESC HEI. I followed the suggestions on the linked page and then figured out that the ESC harness was just making a mess and taking up space.
    I purchased a Pertronix Flamethrower rebuild kit and it came with a 4 pin module and I had the 5 pin. I would have left the esc alone except for the 4 pin 5 pin issue and I couldnt find a 5 pin module on Pertronix' sight. After dropping the coin for that I had to figure out how to use it. I compared a ESC dist. and a non ESC dist. After looking at the differences I removed the complete ESC harness and plug from my distributor. I cut the yellow wires that went to the 3 pin male/3 pin female plug(yellow plug on mine) that plugged into the 3 pin side of the module, then the harness. I put normal spade connectors on the yellow wires and hooked them up to the new 2 pin module. I basically turned my ESC distributor into a non ESC. I then finished removing everything on the firewall that dealt with the ESC.
    I've had no problems with it set up like this. :thumb:

    Z
     
  8. Blazer1AB

    Blazer1AB Registered Member

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    Thanks a million... I have been looking for the way to bypass the ESC. I'm gonna go do this and hopefully I will solve my problem.
     
  9. cwn anwyn

    cwn anwyn 1/2 ton status Premium Member

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    No problem:waytogo:


    Z
     
  10. UD0MEILLD0U

    UD0MEILLD0U Registered Member

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    Replace your ignition switch. Same problem on a friends C10 and it wound up being the switch.
     

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