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Thread: Ignition Systems for Twin Plugged 2.4LS

  1. #1

    Ignition Systems for Twin Plugged 2.4LS

    Once again I throw myself at the foot of the knowledgeable people on this bboard.

    I've got my 2.4LS ready to go back together. I decided to port the heads for twin plugs (already done). Now, the question about 12 plug distributor or a more modern ignition system comes up.

    I have three criteria to trade off each other (in order of importance to me):

    1: Long term reliabillity, maintenance, longevity
    2: Period correctness (my bias is toward the 12Plug Dist)
    3: Cost (initial, as long term cost is sort of wrapped up in #1)

    I read in Wayne's new book on 911 Engine mods that the RSR repro distributor from Andial is like $2K! The other recommended more modern solution is the ElectroMotive unit?

    Can anyone shed opinions (or better, experiences) with going either the 12 Plug Dist route (Kurt's is a 935 dist, can I use that on my engine?), or the ElectroMotive one? Anyone? Bueller (god that GTO was awesome)?
    Chris Purpura @civilizedmisfit
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  2. #2
    Wayne's book recommend twin plugging if your compression ratio is higher than 10:1, plus your piston size is 98mm or more. Piston diameter of 2.4 is only 84mm...

    I can understand your enthusiasm as twin plugging is a great subject.

  3. #3
    Senior Member
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    The only comments that I can offer are that all original parts for any of the Factory-installed twin-plug systems used in the 911R/RSR/935 etc - both Marelli & Bosch- are hard to come by & very expensive.

    There have been numerous discussions in the past about having a batch of new Bosch twin-plug caps made but the cost of tooling for the limited demand would mean that cost would still remain prohibitive.

    Andy
    '69 911E----------->R

  4. #4
    Would the 964 twin distributor setup be suitable for an earier motor?
    Nick Moss - Early 911S #476 - RGruppe #318 - early911.co.uk

  5. #5
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    Nick, the main problem is that in the earlier engines the distributor rotates clockwise whereas the 964 version rotates anticlockwise. You would need to transfer the 'guts' of an early donor Bosch (169 or 184 series) distributor into the 964 body (involving a certain amount of machining to attach/anchor the points plate) including the drive gear.


    Yopurp - contact Steve Weiner at Rennsport Systems:



    http://www.rennsportsystems.com/2f.html

    or Peter Sanchez at Andial:

    http://www.andial.com/content/911/twinplugdist.htm


    Andy
    '69 911E---------->R

  6. #6
    One of the Pelican guys, RACER911RS, put twin plugs in his motor, it may be worth dropping him a line

    PP BBS thread here
    Nick Moss - Early 911S #476 - RGruppe #318 - early911.co.uk

  7. #7
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    Question distributor

    If I were you I would look into Electromtive system (crank fire). It is the way to go! No points, I have it on my 67s, I don't have to use a timing light any more. "http://www.electromotive-inc.com"
    All the Big Boy Racers in my area use it. My earlyS is a track 1st street 2nd type of car with a plate for a drive on the street now and then. Works fine for me. It is what allmost all new cars use today. It was on the MODEL T Ford
    Grover #53
    1967,911-S

  8. #8
    Grover,

    Thanks, checked out the electromotive web site. Informative, but don't see the model for a 911 engine (all honda's, chevy's, etc..).

    Andy, Thanks for the links to Andial and Rennsport. I'll give em a call.

    God that guys engine on PPBBS is incredible (ly scary). I figure he and Kurt must be from the same gene pool.
    Chris Purpura @civilizedmisfit
    ___________
    Member #479
    72T aka The "Civilized Misfit" Build - Helicopter Cooled! See: https://www.excellence-mag.com/issue...vilized-misfit
    2019 911 Carrera GTS (sold, no regrets)
    73S - #1100 (restored and now somewhere in Europe &#128546
    1997 993 Carrera 4S Black on Black (sold &#129394

  9. #9
    Goldmember ttweed's Avatar
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    Originally posted by yopurp
    Thanks, checked out the electromotive web site. Informative, but don't see the model for a 911 engine (all honda's, chevy's, etc..).
    yopurp- try the Clewett Eng. site instead. More Porsche oriented.

    What compression ratio are you running in your 2.4 motor? I have to agree w/ beginner on the benefit of twin-plugging a stock motor. It's very minimal, except for the cool factor (which cannot be ignored).

    TT
    Tom Tweed
    Early S Registry #257
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  10. #10
    Tom,

    Thanks for the link. Geez, maybe that RSR dist isn't looking so expensive, and definitely is cooler. I'm running stock compression, but advanced cam timings from Elgin. My understanding from some books is that I can advance the timing w/twins for more torque.
    Chris Purpura @civilizedmisfit
    ___________
    Member #479
    72T aka The "Civilized Misfit" Build - Helicopter Cooled! See: https://www.excellence-mag.com/issue...vilized-misfit
    2019 911 Carrera GTS (sold, no regrets)
    73S - #1100 (restored and now somewhere in Europe &#128546
    1997 993 Carrera 4S Black on Black (sold &#129394

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