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HEI relay install(PIC'S)

Discussion in 'The Garage' started by BobK, May 26, 2004.

  1. BobK

    BobK 1/2 ton status

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    HEI relay install(PIC\'S)

    I installed a relay to power up my HEI today.
    Pretty easy install.
    I also installed a relay for my heated o2 sensor.
    Here are a couple pic's.
    ALL the pic's can be viewed HERE

    The relays I used.rated at 40 amps.They are DPDT(Double Pole Double Throw) relays.$3.00 each at my local electronics wharehouse.
    [​IMG]

    Ran these wire from a existing IGN. splice at the IGN. switch to trigger the relays on.
    [​IMG]

    Here is the splice I had made at the IGN. switch(kinda hard to see)
    [​IMG]

    I replace my existing 1 wire o3 sensor with a 3 wire(heated) o2 sensor.Here is the retrofit harness.
    [​IMG]

    Here's the new 3 wire o2 sensor installed in the drivers exhaust manifold.
    [​IMG]

    This is the power feed to the relays.Red goes to the HEI relay(12g wire).Blue goes to the o2 sensor relay(16g wire).
    The circuit is protected by a 12g fusable link(light blue wire).
    [​IMG]

    All hooked up now.
    [​IMG]

    Here's the voltage now being sent to my HEI coil 14.12volts.
    Should produce a nice arc!
    [​IMG]

    Took me an afternoon to do this project (pissed around alot though) and maybe $10.00 in materials.
     
  2. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Re: HEI relay install(PIC\'S)

    Man Bob! That is some nice neat work. Top notch and good write up on the upgrade. Looking at putting headers on my 454 Burb with factory FI and I may need to go to a heated Sensor to get it right.. Now I know how. /forums/images/graemlins/thumb.gif
     
  3. Hossbaby50

    Hossbaby50 3/4 ton status

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    Re: HEI relay install(PIC\'S)

    The benefits of this are .......? I imagine that more power gets transmitted to the HEI setup correct? Why do it to the o2 sensor? More accurate reading for the TPI computer? Thanks

    Harley
     
  4. SF87K5

    SF87K5 1/2 ton status

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    Re: HEI relay install(PIC\'S)

    Nice write up. /forums/images/graemlins/thumb.gif

    But I am with Hossbaby50, can you please give us more info on this?
     
  5. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: HEI relay install(PIC\'S)

    I'm still wondering why...... /forums/images/graemlins/thinking.gif /forums/images/graemlins/confused.gif /forums/images/graemlins/whistling.gif /forums/images/graemlins/dunno.gif
     
  6. BobK

    BobK 1/2 ton status

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    Re: HEI relay install(PIC\'S)

    Delievering more voltage to the coil while isolating high amp draw accesories.That's my goal.

    I've done some extensive rewiring of my truck,all based on MAD Electricals ideals.
    http://www.madelectrical.com/electrical-tech.shtml
    I've read thier site front to back and have learned ALOT.

    I've isolated all the major circuits that have a high amp draw,HEI,E-fans,heater fan,electric fuel pump,HO H4 headlights and 55wt Hella driving lights.

    I run relays to these circuits powered by a main or accessory power distribution block.
    This method provides full voltage to these high amp circuits while ridding those circuits of voltage drop.

    Voltage drop will greatly effect how well an accessory will perform.
    In the case of headlights it can lead to poor lighting and dim lights,in the case of a HEI coil,poor performance due to poor spark.

    The isolation of all the circuits helps rid that particular circuit of excess wireing which will again decrease voltage drop which again leads to better performance of that accessory.

    The circuits are fed via a power distribution block.This block is connected to the ALT. and is monitored by the "sense" wire of the ALT.
    When a high amp circuit is turned on it will sense the increase in demand and automatically bump up the voltage being produced by the alt.
    This maintains that "ideal" 14.2 volts that most accessories perform best at.

    All of this is what I learned from reading MAD's site.It's quite informative.

    As for the relay for the 02 sensor,again the o2 sensor is a constant 12V draw that I did not want being fed by the fuse block.
    I wanted it isolated and run off a relay so it performed at it's maximum potential.

    A 3 wire(heated) o2 sensor will help deliver a more consistant reading for the ECM.

    A one wire o2 sensor will heat up and cool down.The o2 sensor needs to be above a certain temp to keep the ECM in "closed loop" operation.
    In "closed loop" the ECM uses the reading from the o2 sensor to calculate fuel delivery based on the amount of oxygen it reads in the exhaust gas.This helps tell the ECM to either lean out or richen the mixture.

    In "open loop" the o2 sensor is not hot enough to give the ECM those readings so the ECM will deliver fuel on preprogramed parameters.
    A fuel injected motor will not perform as well or as efficiently in "open loop" as it does in "closed loop".

    Well...wasn't that long winded!/forums/images/graemlins/grin.gif

    Hope that answered a few questions.
     
  7. POWERMAD

    POWERMAD 1/2 ton status

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    Re: HEI relay install(PIC\'S)

    [ QUOTE ]
    Well...wasn't that long winded!


    [/ QUOTE ]
    Not realy /forums/images/graemlins/ignore.gif
    Nice job /forums/images/graemlins/waytogo.gif
     

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