GM 8 pin HEI Conversion pics

Electrical and Ignition

  1. TrailBeast

    TrailBeast Slightly Twisted Member

    Messages:
    20,325
    Likes Received:
    7147
    Joined:
    Mar 11, 2011
    Location:
    Arizona
    Local Time:
    12:53 AM
    A few weeks ago I decided I was going to end up with a high energy ignition system in my 73 Dart.
    Took me a few weeks of planning in my time off here and there, and lots of investigation of schematics for different coil models and designs.
    At first I was going to use the four pin module like most people that have done it, but an 8 pin module was suggested by (sorry, don't remember) but it was a fellow FABO member.
    That got my curiosity up, so I chked into the 8 pin modules and what made them different or better than the four pins.
    Come to find out that they are not really different aside from the computer controlable chip in them that allows the module to change the ignition timing when the engine needs it to adjust for elevation, change fuel mixtures and RPM changes, as well as engine load changes and the ability to hear and preignition knock and adjust the timing to correct it. (Some EFI packages such as the Mega Squirt use an 8 pin HEI module to help manage the fuel system)

    Well, my car will never have a Mega Squirt EFI system so I don't really need the 8 pin module for a mostly stock 73 carbed 318 and the four pin would have been just fine.
    Normally the computer in a newer car or truck controls the 8 pin module to handle the varying needs of the engine for ignition timing, but we dont have that computer in our old Mopars so what is the point of having the 8 pin module when the four would do the same job? Right?
    I decided on the 8 pin so I would know how to set it up mostly because of this little peice of inginuity, http://www.rabidgator.com
    Thier website is not functional yet, but the pdf document that desribes the product can be gotten here. [ame]http://www.letsgocomputers.com/docs/timingcomputer.pdf[/ame]

    If you need Adobe's Acrobat Reader to view this document, it can be downloaded free here. http://www.adobe.com


    This product looks like it would an invaluable addition to the HEI system.
    It Looks like most any other guage, but these are some of it's fuctions.
    1. Can set base timing, max timing, and even the advance curve all from the guage on the dash.
    2. Has built in rev limiter as well as a shift light with user definable settings.
    3. Has the ability to automatically retard the ignition when using boost, by sensing manifold vacuum and pressure.

    It is able to do this only through the 8 pin module via the extra for pins that control timing.
    This is why the 8 pin ended up being the module of choice even though I'll probably never use those functions, I wanted to know how to set it up, so I gathered the parts from a local Pick it yard and got busy.

    [​IMG]




    More study and time spent thinking over the possible ways of doing it and I was ready to tear into it, so I took all this stuff out.

    [​IMG]


    No more ballast resistor, or ECU or factory coil on my intake and inner fender.:cheers:




    These are the replacements.
    HEI E-coil, 8 pin HEI ECU and heatsink.
    And a rotor with a .060 longer contact to keep arch burning down inside the distributor. (not shown)
    The spade connector that is not connected is the tach lead.
    The plug on the ECU without a connector in it is the port that the controller (guage) I mentioned above plugs into that gives all those added functions of settable base, total and advance curve from inside the vehicle with a lit readout of the settings that are saved to it.

    [​IMG]

    I bolted the new E-coil at the same bolt location that the VR used, and mounted the new 8 pin module and heatsink over the ugly hole where the ballast used to be.




    Removing the original coil, wiring, and bracket made it a lot easier to get at the distributor when needed.
    [​IMG]




    Last step of the install was to change gap on the plugs to .045
    The car fired right up, but I could tell something was off and I had to set the idle mixture screws a little leaner (1/4 turn) to get it back nice and smooth again. (apparently it didn't need as much fuel with a hotter larger spark?)
    I also noticed on the test drives that the car seemed to react and respond better to everything from idle to WOT and seemed to require less throttle to move the car. (maybe my imagination, who knows) but that is the way it seems.

    (I know a few people that will be real interested in this part.)
    Not once today did the car pull it's hot start sputter sputter crap like some of the other Eddie carbed cars out there.
    Have to wait and see if that problem is gone, as it's too early to know for sure.

    I think I'm in love as it seems to have changed a few little things for the better and it's just that much more fun to drive now.
    All said and done, I'm REALLY happy with it and surprised that it made as much difference as it did.
    Looking forward to a gas mileage chk now.

    This is the unit I may settle on to build and sell as a kit.

    Thanks for the heads up on the VR guys, it's fixed now.
    I also finished pulling the ECU.
     
  2. 67Dart273

    67Dart273 FABO Gold Member FABO Gold Member

    Messages:
    40,330
    Likes Received:
    7989
    Joined:
    Oct 14, 2010
    Location:
    Idaho
    Local Time:
    11:53 PM
    Uh................................I missed something????

    The ECU is still in the car. The thing you removed is the voltage regulator
     
  3. TrailBeast

    TrailBeast Slightly Twisted Member

    Messages:
    20,325
    Likes Received:
    7147
    Joined:
    Mar 11, 2011
    Location:
    Arizona
    Local Time:
    12:53 AM
    Yea, I disconnected it and set it off to the side and when everything went on I forgot to hook it back up :banghead:
    Then I realized that the connector is behind the coil so I have to take it back off to get the connector back up there.
     
  4. the67fish

    the67fish Well-Known Member

    Messages:
    1,080
    Likes Received:
    16
    Joined:
    Sep 14, 2009
    Location:
    Fort Worth Texas
    Local Time:
    1:53 AM
    Damn this is getting interesting quickly!!! Wish their site was up and running, I want to see this dash mounted guage item, any descriptions of it?
     
  5. earthmover

    earthmover in the tire smoke

    Messages:
    2,339
    Likes Received:
    52
    Joined:
    Sep 21, 2007
    Location:
    nc
    Local Time:
    1:53 AM
    these guys are going to burn you at the cross..no chevy stuff on there mopar..:prayer::prayer:
     
  6. TrailBeast

    TrailBeast Slightly Twisted Member

    Messages:
    20,325
    Likes Received:
    7147
    Joined:
    Mar 11, 2011
    Location:
    Arizona
    Local Time:
    12:53 AM
    Some may huh? :D
    It's ok.


    Think I saved the PDF when the site had it posted, I'll look and edit here with it.

    Here it is, [ame]http://www.letsgocomputers.com/docs/timingcomputer.pdf[/ame]
     
  7. the67fish

    the67fish Well-Known Member

    Messages:
    1,080
    Likes Received:
    16
    Joined:
    Sep 14, 2009
    Location:
    Fort Worth Texas
    Local Time:
    1:53 AM
    shhhhhh I have a chevy trans in mine lol among a few other parts, even the alternator .
     
  8. the67fish

    the67fish Well-Known Member

    Messages:
    1,080
    Likes Received:
    16
    Joined:
    Sep 14, 2009
    Location:
    Fort Worth Texas
    Local Time:
    1:53 AM
    The one problem Im seeing here is the firing order.... Mopars are Counter Clock wise so Im scratching my head on this one. Maybe I didnt read enuff?
    Vehicle NOT equipped with 7 Pin (Large Diameter Cap)​
    Distributor Installation​
    Locate a new or used (in good condition) large diameter HEI distributor with cap, coil and
    module. IT MUST BE A 7 PIN MODULE WITH THE ADDITIONAL WEATHER PACK
    CONNECTOR HANGING OUT OF IT AND NO VACUUM ADVANCE CANISTER. The
    older 4 pin module with a vacuum advance canister, weights and springs, will NOT work. NOTE
    some GMC trucks came with the 7 pin module AND a vacuum canister. No testing has been
    done at this time.
    With the engine off rotate the crankshaft and set Cylinder One to 10 degrees before top dead
    center.
    Install the distributor and align the magnetic pickup (you can feel a slight detent)
    Whichever post the rotor is pointing should get spark plug wire for cylinder 1
    The remaining firing order should be wired clockwise around the distributor cap
    Wire Switched +12volt power to the BAT terminal​
    Follow the instructions listed in the previous section.
     
  9. 67Dart273

    67Dart273 FABO Gold Member FABO Gold Member

    Messages:
    40,330
    Likes Received:
    7989
    Joined:
    Oct 14, 2010
    Location:
    Idaho
    Local Time:
    11:53 PM
    The ignition module doesn't care which way the distributor turns, and in fact, not all GMs turn the same way. Chibbies turn CW, I've forgotten some Ponchos? Olds? turn CCW

    Mopar SBs turn CW, B/ RB and 426 hemi turns CCW
     
  10. the67fish

    the67fish Well-Known Member

    Messages:
    1,080
    Likes Received:
    16
    Joined:
    Sep 14, 2009
    Location:
    Fort Worth Texas
    Local Time:
    1:53 AM
    I was gonna have to think about that, 2am and my brain aint working good LOL. Looks like for a BB mopar with electronic dist just unhook the vacuum advance and pin the weights down or remove then, plug the two wire connector in and fire it up. Damn I seem to have most all of that laying around, wonder how much their fancy little computer is?
     
  11. TrailBeast

    TrailBeast Slightly Twisted Member

    Messages:
    20,325
    Likes Received:
    7147
    Joined:
    Mar 11, 2011
    Location:
    Arizona
    Local Time:
    12:53 AM
    Even if there is a rotational limitation one would think a simple software change could easily remedy this. (afterall, if the unit can be set for different quantities of cylinders it's probably already programed for direction changes.)
    I don't see how firing order would matter, but it would matter if the retard and advance functions only worked one way.
    I'd bet that has already been addressed since as 273 stated Chivy makes engines of both directions that use the same ECU controls.
    Somewhere in the process I saw a device made by MSD that can alter the timing via the 8 pin module with a type of dial that has degrees of advance marked on it, but I think that was all it did.
    Just the possibility of being able to do this, and the fact that some EFI systems used it was the main reason I went with the 8 pin, until I ran across that timing computer.
    After that, all kinds of possibilities opened up for using the 8 pin module.

    To the67fish,
    I think you are right that as long as the distributor was not allowed to make any mechanical changes in the timing it should work fine.
     
  12. waid302

    waid302 Member

    Messages:
    20
    Likes Received:
    7
    Joined:
    Apr 10, 2013
    Location:
    Indiana
    Local Time:
    1:53 AM
    Hello TrailBeast,

    I am a new member

    I am here and very interested in this 8-Pin HEI module setup. GM introducted the 8-pin HEI in 1988 - full 14 years after the 4-pin HEI came out back in 1974 so its safe to assume its "better" than the 4-Pin HEI.

    At one time I had a 77 Olds Omega (Chevy Nova) and was going to convert to TBI. I don't the Omega anymore but still have 3 original GM 8-Pin modules and a HEI Coil. I recently bought a 64 Ford Falcon and doing a 5.0 swap with Duraspark Distributor & HEI Ignition Module. The Duraspark Ignition Box also has a bad reputation. A lot Ford guys & others always seems to use the 4-Pin HEI module. Very little information is available on the 8-Pin HEI with carb setup.

    Do you still have mechanical advance with 8-Pin HEI ?

    Have you observed any timing retard (which I believe only work with ECM) during start with 8-Pin HEI ?

    Thank you,

    Waid
     

    Attached Files:

  13. BillGrissom

    BillGrissom Well-Known Member

    Messages:
    7,284
    Likes Received:
    348
    Joined:
    May 10, 2009
    Location:
    Sacramento
    Local Time:
    11:53 PM
    There have been many posts on HEI modules since TrailBeast's Aug 2012 post. He now sells an 8-pin HEI kit. Last summer, I grabbed junkyard parts and put on my 64 slant. I read about the 8-pin module on a megasquirt site (search, good info there).

    TrailBeast recently related that the designer of the Rabid Gator Timing Controller dropped it after getting a good day job. Kit Carlson here is working on a custom spark controller (search posts). The only other box I know of that can control the 8-pin is a Holley Commander 950 ECU, but perhaps other after-market controllers can. Without that, you need to retain the mechanical and vacuum advance in the Mopar e-distributor. I have a Commander 950, but plan to have that just add to the distributor's advance, so I have the ability to easily run without the ECU. I also installed a knock sensor and module from a GM TBI engine, which the ECU can monitor to operate just below the knock limit. The sensor screws right into the 1/4" NPT block drain plug in SB & BB, or with a 3/8" NPT bushing in my slant.

    Looks like you will need an e-core coil. Simplest is the GM "external coil" since one of your connectors goes to that, but you need the other GM connector for the supply and tach output, which you can buy separately (Summit, Autozone?). You also need a Mopar e-distributor and both "double bullet" connectors. Whey you connect the grn & yel wires to it, you have a 50% chance of getting the polarity right. One way will run very poorly, if at all.
     
  14. TrailBeast

    TrailBeast Slightly Twisted Member

    Messages:
    20,325
    Likes Received:
    7147
    Joined:
    Mar 11, 2011
    Location:
    Arizona
    Local Time:
    12:53 AM
    Hello Waid,
    Bill pretty much covered it (Thanks Bill)
    I would add that the megasquirt EFI systems also use the 8 pin module for timing control.
    My setups don't use the timing functions of the 8 pin unit, only the ECU for the ignition, but I use them because they are used by Holley and Megasquirt and they are more tolerant of low voltage than the 4 pin.

    So, yes you still use mechanical and vac advance with them as there is no computer to control them with unless you buy or build one.

    There is no timing retard unless .5 volts is applied to the "D" (white wire) on the four pin weatherpack connector.
    With that .5 volts applied the ECU will go into "Limp Mode" retarding the voltage 10 degrees.
    This function may or may not be applicable to boosted (turbo) systems, but I have not verified how much retard is needed for certain amounts of boost, or if the .5 volts is just on or off and not variable.
    I would think it's on or off only, but I have not tested that theory yet.
     
  15. waid302

    waid302 Member

    Messages:
    20
    Likes Received:
    7
    Joined:
    Apr 10, 2013
    Location:
    Indiana
    Local Time:
    1:53 AM

    In theory, I cound apply .5 volts to the D terminal when the starter is engaged and retarding the timing by 10 degreed thus making it faster start ?

    Waid
     
  16. txstang84

    txstang84 Well-Known Member

    Messages:
    4,488
    Likes Received:
    437
    Joined:
    Oct 10, 2011
    Location:
    Abilene, TX
    Local Time:
    9:53 PM
    true story...sounds like the timing is severly retarded...
     
  17. TrailBeast

    TrailBeast Slightly Twisted Member

    Messages:
    20,325
    Likes Received:
    7147
    Joined:
    Mar 11, 2011
    Location:
    Arizona
    Local Time:
    12:53 AM
    The 5 volts volts to the "D" terminal WILL retard the timing by 10 degrees.
    That part isn't theory.
    If you need to retard your engine that much to start it, makes me wonder what your initial timing is.

    Sorry, I was typing .5 volts and it is actually 5 volts.
     
  18. waid302

    waid302 Member

    Messages:
    20
    Likes Received:
    7
    Joined:
    Apr 10, 2013
    Location:
    Indiana
    Local Time:
    1:53 AM
    Trailbeast,

    I am in the process of completing my motor build and I have Ford's Duraspark Distributor with magnetic pickup. When I started to look in to the Duraspark Ignition Module, I realized that they are not reliable and there are other options. When I came upon your post, it hit that I already have 2 original GM and 1 after market 8-PIN HEI Module and 1 HEI Coil.

    The Duraspark Ignition Modules on Ford (Blue & Red) does have start retard function which aid in starting.

    For less than $5, I can get a +5V DC converter which I can wire to the starter relay so I can retard the timing during start. I figure it could only help a carbureted engine so you dont have to crank as much!

    Thanks

    Waid
     

    Attached Files:

  19. TrailBeast

    TrailBeast Slightly Twisted Member

    Messages:
    20,325
    Likes Received:
    7147
    Joined:
    Mar 11, 2011
    Location:
    Arizona
    Local Time:
    12:53 AM
    Waid,
    I have my timing set pretty high due to my elevation and I don't have any starting problems at all.

    Radio Shack has a 12 to 5 volt regulator that we sometimes use for our guages when the factory one goes out.
    I think it was about $1.79 or something like that. (The main reason I mention this is it is a tiny little thing)
     
  20. Old Tired Rebel

    Old Tired Rebel Legandary Member Legendary Member

    Messages:
    12,478
    Likes Received:
    251
    Joined:
    Oct 10, 2009
    Location:
    NC
    Local Time:
    1:53 AM
    Trailbeast give me a little time and I will be ordering 2 kits from you. One for my Doba and one for my Dart
     
  21. TrailBeast

    TrailBeast Slightly Twisted Member

    Messages:
    20,325
    Likes Received:
    7147
    Joined:
    Mar 11, 2011
    Location:
    Arizona
    Local Time:
    12:53 AM
    All the time you need my friend.
    Thank you, so how about tomorrow? :D

    Just kiddin ya
    Whenever you are ready.
     
  22. BillGrissom

    BillGrissom Well-Known Member

    Messages:
    7,284
    Likes Received:
    348
    Joined:
    May 10, 2009
    Location:
    Sacramento
    Local Time:
    11:53 PM
    waid302,
    Your last post shows you have all the parts needed, besides the Mopar electronic distributor. When you install it, put the HEI module on some type of heat sink, even a flat aluminum plate, with heat sink compound underneath. Those rusty hole rivets are the gnd electrical connection, so clean them well.

    I ran a separate ground wire from the mounting bolt to a good ground junction. If people did the same with their Mopar modules and voltage regulators there would be fewer posts about strange electrical problems.
     
  1. This site uses cookies to help personalize content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.