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HEI Conversions

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by Roostr84, May 19, 2001.

  1. Roostr84

    Roostr84 1/2 ton status

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    Has anybody ever run the conversions to change the points distributor to breakerless? What advantage does this offer to swapping to an HEI, or are they the same? I have heard to stay away from the petronix unit, as it is failure prone but have seen them marketed by Mallory too. Thought it would make for an interesting project, plus cheaper than buying the small cap unit from MSD for $250. I do however have a normal (large cap) distribtor that ran fine when pulled. How hard would it be to get this too fit. I know clearance seems to be a real issue. Anybody been able to make the large cap work for them with the stock motor location?
    Thanks for any help.

    Chris =)
    http:// www.roostr84.coloradok5.com
     
  2. smp

    smp 1/2 ton status

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    I converted mine to HEI with an Accel super coil and Accel 10.8mm wires with no clearance problems it is tight but still fits. The HEI is great more spark and nothing to adjust unlike points the swap was easy all you need is the dist., cap, rotor, coil, and wires.


    <A target="_blank" HREF=http://WWW.SMP.COLORADOK5.COM>http://WWW.SMP.COLORADOK5.COM</A>
     
  3. ErikH

    ErikH 1/2 ton status

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    You answered my roller rocker question, now I'll answer your ignition question.

    About 3 months ago I installed Crane Cam's hi-perf XR3000 points conversion kit in order to do away with the old points... The unit relies on a light sensor thingy that replaces the points plate inside the distributor. Along with that, there's a small control module that controls dwell. The system is solid, and built for abuse, but it's a little time consuming to install. I also installed a hi-voltage coil, also made buy Crane. With new plug wires by MSD, I spent about $195 all together.

    I noticed an immediate improvement over the points, and I like the fact that I never have worry about resetting the timing or adjusting the points. Definitely worth it.

    Check out Crane's site: http://www.cranecams.com/ignition1/7003000.htm
     
  4. Triaged

    Triaged 1/2 ton status

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    I have a HEI in mine. It fits snug. The ring that clips over the plug wires rubs aginst the firewall a bit (If the ring was not there it would not rub at all). High performance external coils are easer to find than the in cap HEI type. You would also be able to open up your plug gap a bit and this would give more power and more MPG.

    '71 Blazer CST with alot of rust
     
  5. cleszkie

    cleszkie 1/2 ton status

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    I swapped out my points distributor for a Mallory Unilite unit. Also swapped out the points coil for a high performance Mallory electronic coil. It was as easy as removing the stock unit, sliding in the new unit, and hooking up three wires and adjusting the timing. Was even able to keep the stock ballast resistor. The Unilite distributor is one that relies on a photo electric triggering devise that never goes out of adjustment (supposedly). The K5 never ran better. No more dwel angle to F with.
     
  6. Steve_Chin

    Steve_Chin 1/2 ton status

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    Some guys like Pertronix, some swear at 'em (check: <A target="_blank" HREF=http://www.classicalpontiac.com/qa7/display.cgi?number=20036>http://www.classicalpontiac.com/qa7/display.cgi?number=20036</A> for a little discussion). Same goes for Mallory. My major dislike for the conversion kits is the limited availability of service parts. I know a guy who does beautiful electronic trigger conversions to points distributors that use nothing but easy to get parts (stuff you can find in any parts store), from the ignitor modules, to the reluctors, to the pickups. His name is David Ray, his e-mail is sparkman451@earthlink.net, and his phone number is (562) 699-6949. Good dude and very knowledgeable about ignition.

    FWIW, I have a modified large body HEI out of a '77 Caprice. The fit is *very* tight. I'd prefer not to run it if I didn't have to, but since I'm going to convert to TPI in the near future I don't see the logic in spending the $$$ to convert a points distributor.
     
  7. Roostr84

    Roostr84 1/2 ton status

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  8. Sledge

    Sledge Registered Member

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    The TPIs in 86-87 F-Bodies and I think all TPI Vettes used a large cap HEI with a seven pin module. They have the same external dimensions as the older non-computer controlled HEIs; they just have an extra 4-pin weatherpak connector for the controller feedback. In fact now that I think of it, my '85 Blazer w/ ESC has the same HEI setup.

    There are a bunch of us doing TPI conversions to our first-gens, eh? Cool beans. Gotta love GM parts interchangeability.
     
  9. Steve_Chin

    Steve_Chin 1/2 ton status

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    I've got an '86 TPI ECM and harness but I have modified it for use with the later small-body HEI of the '88-up (except Pontiac Formula, which used the large body unit until '90 according to a few sources I have) vintage. I've also modified it to work with the '89 non-cold start injector MAF setup.

    FWIW, the older HEI will not work with the TPI setup because all of the ignition timing changes are made in the ECM, not in the distributor. That's the reason for the 7-pin module and 4-pin connection to the ECM.
     
  10. Roostr84

    Roostr84 1/2 ton status

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    Wow, thanks for clearin that up. I was curiopus if the difference between the computer controled HEI and the non comp HEI would cause you to switch to the newer style. Since you have answered all my questions to date.. how about this one...what came first the chicken or the egg? hehe

    Chris =)
    http:// www.roostr84.coloradok5.com
     
  11. Steve_Chin

    Steve_Chin 1/2 ton status

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    Egg... Reptiles had eggs before God thought of making a chicken... &lt;GRIN&gt;
     

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