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Replacing old dist.

Discussion in 'The Garage' started by dirtynails, Jul 30, 2006.

  1. dirtynails

    dirtynails Registered Member

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    This is for an '83 full size Blazer originally equiped with a 305 engine and now has a pretty new 350 Chevy universal crate motor. 700r4, NP208, 10 bolt corporate, 3.73:1 gears. Edelbrock 1904 qjet, no thottle position sensor. Computor under the dash, knock sensor on the side of the engine. The old distributor is perhaps an EST HEI although there is no EST module on the firewall. It has a vacuum advance, 5 spade ignition module inside under the rotor along with a condensor or capacitor, 4 wires (black, white, green, brown) going to the weather pack connector and then going through the firewall to the computer under the dash. The old distributor has over 300K miles on it and the advance weights are getting a little sloppy.

    I need advice on what distributor to buy and how I will hook it up since it probably won't have as many wires (4) to go to that weather pack connector. I bet they have only 2 or 3 wires to go to the computer right? So that's where I get confused.

    I don't need a real fancy expensive one just a good decent one. The Cardones seem to be the cheapest. Are they OK or is it worth getting something else?
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    Any chance you can get a photo of the distributor with the cap off?

    I believe it was Summit that was selling distributors pretty cheap awhile back, might want to try searching the board and see if they are still reasonable.
     
  3. dirtynails

    dirtynails Registered Member

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    Sorry I don't have a digital camera.
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Hmm...I'd like to get a photo of it, it proves that at some point, GM was still using the vac advance/mech advance distributors with ESC/EST, and later on they went all electronic.

    Would help people determine which distributor they have, and whether it can be converted to "standard" operation, like yours.
     
  5. broncoman6524

    broncoman6524 1/2 ton status

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    how do you tell if the magnets are getting sloppy i have the same dist, but mines an 84
     
  6. dirtynails

    dirtynails Registered Member

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    So, OK I don't have the answer as to how I can get a photo to you yet but I was just now doing some more research in my chevy shop manual (Light Duty Trucks 10-30 series 1983 Chevrolet and I am now thinking I should be calling it an HEI ESC distributor and not an HEI EST. I must say this stuff just confuses the H out of me. But anyway what is pictured in the book in the ESC wiring schematic on the Engine Electrical 6d-57 page is exactly what I have. Does that help?
     
  7. misterfnygy

    misterfnygy 1/2 ton status

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    You can easily swap in a traditional HEI. I am not sure if you want to keep the computer or not-
    A traditional HEI will hook up easily- one power wire and a tach feed. It gets the signal from the camshaft. You can then just remove the computer and use the traditional meachanical/vacuum advance. I did this on my last K5 because the only replacement distributor was more than the traditional. The other option would be to have your current distributor rebuilt and keep everything the same.
     
  8. dirtynails

    dirtynails Registered Member

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    OK, I think I understand this. So I would leave any wires going to the computer thingy under the dash not connected to the distributer at all. Just tape them off. And since I don't have a tachometer guage, that would leave me with only a one wire hook-up. The pink wire to the bat terminal. Does that sound right?
     
  9. misterfnygy

    misterfnygy 1/2 ton status

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    sounds good to me. Sell the computer or throw it as far as you can!!
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    If you search out a post at most 2 days old, it shows with pictures (not sure if you can view them though!) how to convert an ESC/EST distributor to "normal" operation. The module is different, so it needs a couple of wires cut/spliced to work correctly.

    I suppose you could just swap modules as well, but I have yet to see an ESC/EST distributor opened up.

    ESC and EST were both terms used by GM for that setup (some sort of timing control without the entire engine being controlled via ECM) but I have no idea why they got rid of one and went with the other. It could be linked to a change in how they function, since some used vac/mech advance and some didn't.
     
  11. dirtynails

    dirtynails Registered Member

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    Thanks everybody, now I know how to hook up the new HEI and disconnect the EST. I'm not sure I can totally get rid of that computer thingy yet, there's a couple of more things I will need to track down: 1. I thought I read somewhere that the Torque converter lock-up interacts somehow with the computer to get the engaged and unengaged. 2. There is the EGR bleed solinoid mounted on a strap connected to the thermostat housing. The EGR bleed gets a signal to let off the EGR at certain mysterious times. I will look at that some more and probably ask some more questions.

    Thanks again.
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

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    If your truck doesn't have a computer controlled carburetor (a total of 3 electrical connections each at different spots on the carb) it won't affect anything else.
     

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