AMC 258 DS distr conversion

Discussion in 'Injection Tech' started by Bill USN-1, Dec 25, 2012.


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  1. Bill USN-1

    Bill USN-1 Moderator Staff Member Moderator

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    Along the same lines as the AMC 401, IH used the AMC 258 6 cyl engine. This one was used much more than the 401 mainly because of the lack of a modern inline 6 from IH to fit between the 4 and 8 cyl IH engine.

    I chose the already avail AMC Duraspark distr as used by AMC/jeep in their production vehicles in the early 80's. AMC was like IH and used a lot of technology and products developed by the big 3. The Ford Duraspark was a very good distr design and is still used by most of the top aftermarket distr makers like MSD.

    These are redily avail in junk yards and on ebay either used, new or aftermarket. You can also find then new or reman at your local parts store or places like rockauto.com for about $40-45.

    Carbs
    For those wanting to upgrade the ignition to run with a carb, just drop in this distr and then wire it up to the 4 pin GM HEI module and the square coil as shown in the ignition FAQ. Ignore the rest of this, it's just for EFI.


    EFI

    Same basic design as most DS setups except one....I'll get to that shortly.

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    Remove the reluctor. I use a couple large screwdrivers under the center of the reluctor wheel.

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    Then remove the 2 scews in the base plate.

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    Now for the mech adv I like to remove the weights just to reduce the pressure from them as the rpm increases.

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    Then I used a simple tack weld to lock the advance shaft in place. You could also wire it tight in place of the springs or drill and tap and install a screw and locktite.

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    Then clean it out and install the base plate.

    now the rotor phasing needs to be corrected just like all the other distr conversions.

    The one difference with this DS distr is the adv plate does not rotate directly around the middle. It has a pivot pin on the opposite side. So it does not evenly pass by the reluctor and the gap changes slightly.
    On some of the other DS dist's you could remove the vacuum adv arm and rotate the base plate clockwise to retard the timing and then lock it down or what I normally do is drill and tap the reluctor so i can adjust the phasing there.
    If you adjust the phasing by moving the base plate keep the reluctor gap in mind. if it moves away from the pick up it weakens the signal.

    Here is the Advance arm disconnected and plate rotated clockwise.

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    Drill and tap plate to lock it down at the proper phasing.
    This means the trailing edge of the rotor should be at the trailing edge of the distr cap terminal as it just passes it.

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    How i prefer to do it is to leave the adv plate connected to the vac adv to hold it in place and drill and tap the reluctor. i use a 6-32 set screw,

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    Then set the reluctor phasing and lock down the set screw.

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    That's about it.
    Cut the connector off and splice some wire and terminals to connect to the P and N terminals of the 8 pin module.
     
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