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HEI to Mallory unilite conversion

Discussion in 'The Garage' started by nova, Mar 11, 2007.

  1. nova

    nova 1/2 ton status

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    I have a 77 blazer with a HEI in it. I just picked up a new unilite from a buddy for free:D . I also picked up a msd 6al ing. box from jegs. I'm looking to install the unilite but there is no instructions on how to go from hei to a points style of distributer. The msd ing. box is easy once i figure out how to install the unilite to the factory hei wires. And then there is the question of a ballist resistor or a capasitor, do i need them?:confused:

    Any help out there on this subject?
     
  2. 85mudbogger

    85mudbogger 1/2 ton status

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    not tryin to start something but why are u wantin to put in a points style, the hei is a way better dist, i would just put the msd 6al on the hei, its easy and a good upgrade to your hei, the hei is one good thing about gm imo.
     
  3. nova

    nova 1/2 ton status

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    My HEI took a dump and the Mallory unilite like i said was free. There is no points to wear out in a unilite it has some photo optic infrared LED system deal in place of the points, it and a blaster 2 offroad coil puts out just as much as an HEI.
     
  4. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    The unilite electrics go bad often. Also you would have to change plug wires or at least the cap end of them. The GM modules are cheap and easy to replace. Just replace the GM module and install the MSD box on your HEI and you're set.

    EDIT: Before anyone says anything about a GM module going bad it is way easier to walk into any parts store and buy a GM module over a unilite module.
     
  5. Beast388

    Beast388 1/2 ton status

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    X2

    After my third unilite unit failed (first two were replaced under warranty) I switched back to points until I rounded up the HEI stuff to convert. When they failed, there was NO warning.....truck just wouldn't start.:mad:

    Unilites are junk......and HEI parts can be purchased just about anywhere.:deal:
     
  6. dbozman

    dbozman 1/2 ton status

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    Free or not, no way I'd swap out HEI for a unilite. Had one in an old project GTO of mine; piece of junk. The electronics inside are expensive and die often with no warning. You can get the proper module to install in your HEI cap to run the 6AL box. That's what I'd do.
    d
     
  7. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    I concur...... Never been a fan of Unilites...
     
  8. ntsqd

    ntsqd 1/2 ton status

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    Another No Unilite vote.

    I believe MSD makes a harness that by-passes the stock HEI module so that the 6A is triggered directly by the HEI pick-up coil, no need for the stock HEI module. Look up MSD's page & dig into their on-line tech manuals.
    I just did something like this on Javier's race truck, but I don't recommend doing it the way I did as you can't back up. With the MSD harness you can go back to stock.
     
  9. Beast388

    Beast388 1/2 ton status

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    That is correct. I have mine set up that way.:D
     
  10. nova

    nova 1/2 ton status

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    Thanks everyone for the info I'll check into it
     
  11. Slapperbar

    Slapperbar Retired Navy NDT Examiner Premium Member

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    NTSQD is right. The MSD DOES replace the GM module. IMO the Unilites are crap.
    Go with the MSD.
     
  12. Thunder

    Thunder 3/4 ton status

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    I used to really like Unilites they were very dependable when Mallory made them. About 10 years ago Mallory was bought out by Mr Gasket and quality went down the drain. I knew a guy that worked at the Mallory plant when Mr Gasket took over. He said they started taking short cuts and bought cheap materials. Got rid of all the old employees that were experienced. They could care less about quality Mallory ignitions used to have . All they cared about was using the name.
    Its strange... Mr Gasket also owns Jacobs ign, and Accel. I dont have a high oppion of either of them either.
    Maby thats why MSD is recognized as the best Ign stuff around
     
  13. ntsqd

    ntsqd 1/2 ton status

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    FWIW I've had good luck with the Crane HI-6 stuff (A direct competitor to the MSD 6). I like that their rev limiter is built-in instead of being yet another space consuming box with more wire connections to fail.
     
  14. Slapperbar

    Slapperbar Retired Navy NDT Examiner Premium Member

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    6-AL is built in. That's why there's an L in the name. I've seen two engines detonated that were directly caused by the Crane ignition.
     
  15. 85mudbogger

    85mudbogger 1/2 ton status

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    yes it just uses a rpm pill u plug in the bottom of the box for the rev limiter, u buy the pills seperately and i comes in like a 4 or 5 pack or somthin or other, very easy to change and very easy to hook up to your hei too, took me longer to mount it than to hook all the wires up
     
  16. ntsqd

    ntsqd 1/2 ton status

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    And the situation was such that an MSD being there instead would not have done the same thing? Were both Crane's of the HI- series or the older Stinger XR700 series? The XR's were an ancient design, & not a lot better than points.

    As to the rev limiter, the Crane is still a better bet. There are no pills to buy or have fall out. They use a pair of small rotary switches.

    Better than all of the above are the M&W Ignitions, but like an EFI system you're going to have some development time in plotting an ignition map. Their catalog pdf has a lot of interesting info in. We use one of their ignitions on the dyno at work.
     
  17. Slapperbar

    Slapperbar Retired Navy NDT Examiner Premium Member

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    The engine failures were directly related to the ignition, and yes a dial is more convenient. BTW I've never heard of a pill falling out, not that it's never happened.
     
  18. ntsqd

    ntsqd 1/2 ton status

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    What I'm asking is were those failures the result of a problem unique to the ignitions used, or could any ignition system have caused those failures?

    To say those engines failed due to an ignition problem, and then say that Crane ignitions were used and therefor Crane ignitions are bad isn't fair to Crane or to those reading this thread.
    If the Crane units had a unique failure that any other ignition system most likely would not have had in that application, then you can put the engine failure blame on the ignition brand itself.
     
  19. Slapperbar

    Slapperbar Retired Navy NDT Examiner Premium Member

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    From what I was told by the Dyno operator it was the Crane ignition only.
     
  20. ntsqd

    ntsqd 1/2 ton status

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    I should have asked this in my last post, what sort of failure(s) were they?
     

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