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chevy 250 to HEI

Discussion in 'The Hokey Ass Message Board' started by oneshotwebb, Jun 12, 2008.

  1. oneshotwebb
    Joined: Jun 5, 2008
    Posts: 4

    from Atlanta

    I am trying to put an HEI on my 72 chevy c-10. I have a stock distributor, cap and coil. however, there seems to be nowhere on the coil to plug in the tac or 12 volt switch. If ya got any ideas, let me know. If you need a few pictures or more info on the parts, hit me up. Id like to get this switched over soon as it is my daily driver. Thanks!
  2. Do you have the HEI dizzy now? If so, is that what doesn't have the provision for a tach?
  3. Fat Hack
    Joined: Nov 30, 2002
    Posts: 7,708

    Fat Hack
    from Detroit

    Some 250 Chevy six engines with HEI had the coil mounted to the engine block rather than on the cap, so those won't have the common provisions for Tach and Ignition wires on the cap that you find on typical V8 HEI distribtuors. The tach and ignition wires go to the coil.
  4. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 20,763

    Bruce Lancaster

    First year only I think...'75?? Get the plug that goes with the thing to both clarify the hookups and make llife easy. I've done both kinds, and prefer the integral unit because parts are much easier to find. The first year unit is an oddball used only on nearly extinct cars. Use V8 Moroso fast curve kit, and getting a heavy truck or aftermarket vac can with about half the advance is almost mandatory becaus the EGR application passenger cans ping like crazy when run without EGS...they can crank in like 20+ degrees extra advance.
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  5. Snarl
    Joined: Feb 16, 2007
    Posts: 1,640


    The versions with the separate coil are for A/C applications.

    Moroso makes an adjustable vac advance, its the same for both V8 and L6 applications.

    It is possible to swap it over to an integral style cap and rotor, but you will need to file a new locator notch into the housing as the indexing is different between the two cap designs. It's easier to just get the right dizzy...
  6. dare-to-be-different
    Joined: Apr 7, 2007
    Posts: 883

    from Illinois

    I second this guys solution if you want to change over.

    If yours has the plain cap without the coil-in-cap setup traditional to the more common HEIs, you can take the cap, rotor, coil etc from another 6 cyl, and add it on.

    BUT, if the ignition works fine now, and if the only thing you need is to hook up a tach, and you don't care to change over, you can simply wire the tach in the traditional manner as if you were installing it on a points ignition, and simply hook up the tach trigger wire to the NEG terminal on the coil the same as you would do when hooking a tach to a conventional ign.

    The terminal that goes to NEG side of coil is also the same one that hooks to the points on the older igns. That is what most tachs use to get their signal to count the pulses and count engine revolutions.

    It is possible that it may not be the same with ALL tachs, but that is how it works with all the "normal" tachs I have worked with so far.


    This picture shows that it should be the "C" terminal for the usual tach "counting" signal.
  7. oneshotwebb
    Joined: Jun 5, 2008
    Posts: 4

    from Atlanta

    MAN! Thanks to all of yall! Thats some service. I owe everyone a round if ya ever find yerself stuck on the side of the highway in Atlanta!
    Ill get back and let ya know how it works and If I have anymore questions.
  8. 63ChevyII
    Joined: Dec 9, 2005
    Posts: 560


    The 292 in my 70 C-10 has the coil on the block. The distributor might be bad and I have a coil in cap (brand new) that someone gave me. Not sure if I'm going to use that or go back to the old style distributor with the petronix unit I have sitting on the shelf.
  9. oneshotwebb
    Joined: Jun 5, 2008
    Posts: 4

    from Atlanta

    I made a mistake in my question guys, sorry. I have a points distributor now, I am trying to change to an HEI. I aquired a distributor, cap and coil from a 75-+ camaro with an L6. This is the distributor, coil that has no tach or 12 volt switch plug ins. It may not make a difference, if so, let me know. Thanks again fellas.
  10. 53sled
    Joined: Jul 5, 2005
    Posts: 5,822

    from KCMO

    There is a plug for power and another for the tach, and a ground strap. HEI is real easy, when complete.
  11. find a complete unit it will be much easier.

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