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Is this distributor cap shot?

Discussion in '308/328' started by Sledge4.2, Feb 14, 2010.

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  1. Sledge4.2

    Sledge4.2 F1 Rookie

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    #1 Sledge4.2, Feb 14, 2010
    Last edited by a moderator: Sep 7, 2017
    On one post, there is an approx 1mm groove that looks like its has been carved out by the rotor. Is this cap toast? Any what the hell causes this, is it physical contact or spark? the rotor corresponding to this cap looks fine.

    This terminal is the worst. One terminal is about 1/2 as bad, and the other two look fine.

    Geno 1978 GTS
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  2. BigTex

    BigTex Seven Time F1 World Champ
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    #2 BigTex, Feb 14, 2010
    I think ALL the contacts are renewable?

    Only a crack can kill a cap.

    You either had a bad rotor at one point (dimensionally out of spec) or maybe your distributor bushings at the shaft are shot??
     
  3. mustardfj40

    mustardfj40 Formula 3

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    #3 mustardfj40, Feb 14, 2010
    Are they aftermarket distributor/rotor?
     
  4. ClydeM

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    #4 ClydeM, Feb 14, 2010
    have a source for parts?
     
  5. Steve King

    Steve King F1 Rookie

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    #5 Steve King, Feb 14, 2010
    Either it looks like the cap was installed wrong or the top bearing on the dizzy shaft is bad which causes the rotor to not run true. I do not believe you can replace these. The best you could do if you were careful would be to fill the groove with solder.
     
  6. Sledge4.2

    Sledge4.2 F1 Rookie

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    #6 Sledge4.2, Feb 14, 2010
    They look like OEM.

    I just my mechanic install pertronix, and while installing he replaced all 4 bearing indicating they were shot and thats why the groove in the distr terminal.

    I just ordered two new (repro) caps at $170 per side.
     
  7. Ferraripilot

    Ferraripilot F1 World Champ
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    #7 Ferraripilot, Feb 14, 2010
    This happens when the caps are not tightened to flush with the surface. The caps fit pretty tight so when one cannot see the bottom of the cap it is easy to assume the cap is fully fastened. Same thing happened with one of mine a while ago.
     
  8. Verell

    Verell F1 Veteran
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    #8 Verell, Feb 14, 2010
    John's got it,
    The caps were probably either installed 'cocked', or more likely, worked loose & settled down on the rotor at an angle.

    While I can see how a bad distributor bearing would let the rotor wobble around, I'd expect the resultant wear to be uniform.
     
  9. Sledge4.2

    Sledge4.2 F1 Rookie

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    #9 Sledge4.2, Feb 14, 2010
    do you think that much wear would affect the firing of those plugs?
     
  10. Verell

    Verell F1 Veteran
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    #10 Verell, Feb 14, 2010
    Last edited: Feb 14, 2010
    I'm sure the plugs where the rotor was touching the distributor cap contacts would fire just fine. As for the other contacts, the size of the gap would determine whether or not the plugs would fire properly.

    However, when the cap was properly seated, most likely the worn contacts would have an excessive gap with the rotor tip & firing would be marginal at best. Also, with enlarged gap, the liklihood of a 'carbon track' forming would be greatly increased.
     
  11. Sledge4.2

    Sledge4.2 F1 Rookie

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    #11 Sledge4.2, Feb 25, 2010
    Last edited by a moderator: Sep 7, 2017
  12. Sledge4.2

    Sledge4.2 F1 Rookie

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    #12 Sledge4.2, Feb 25, 2010
    Last edited by a moderator: Sep 7, 2017
    About 6 months ago I went for the Accel wires, but was getting ohm reading in the 15k range. The Accel center core is so thin I am not sure how you can get a good piercing. Also, the plug boots on the Accel set makes it hard to get the wire in the front bank, and having taken them off a few times I wonder if all the bending created a short.

    I went with the Taylor Spirocore, its a much thicker center core. I bought the set TAY 73255. They are 8mm wires vs 7mm stock.
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  13. Sledge4.2

    Sledge4.2 F1 Rookie

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    #13 Sledge4.2, Feb 25, 2010
    Last edited by a moderator: Sep 7, 2017
    I wanted to keep the basic setup somewhat stock, so I had my mechanic install pertronix, keeping the two distributors, but getting rid of the points.

    I saved the original plug wires set, and pulled the boots off for re-use. Then I cut off the Taylor plug wire boots carefully with a razor blade, then slipped the OEM boots back on the new wires.
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  14. Sledge4.2

    Sledge4.2 F1 Rookie

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    #14 Sledge4.2, Feb 25, 2010
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    Then clipped a little bit of the outer red rubber sheathing, and doubled back the inner wire, using some of the silicon grease that came with the Taylor set, very tight fit since these are 8mm vs. 7mm stock
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  15. Sledge4.2

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    #15 Sledge4.2, Feb 25, 2010
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    I bought new spark plug boots, $9 each at AW Autoparts, the old ones nearly disintegrated when I pulled them off.

    I used Brake cleaner to remove the taylor white lettering on the plug wires.

    Looks somewhat OEM, not after the completely original look as thats not what this 308 is..
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  16. Sledge4.2

    Sledge4.2 F1 Rookie

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    #16 Sledge4.2, Feb 25, 2010
    Last edited by a moderator: Sep 7, 2017
    About 6 months ago i bought 8 new extenders, which have been on the car since then (when I installed the accel wires). I tested the wire resistance without the extenders first, and got all less than 1k ohm. Then I retested the extenders, 0 ohm. Then I put the extenders on and tested and low and behold one the extenders was cutting out when I wiggled the plug wires around. Measured 0 when static, but when attached to the plug wire and wiggled it would cut out. Replaced that extenders, which is odd bc it was only 6 months old at best.

    Final readings for resistance
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  17. Ferraripilot

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    #17 Ferraripilot, Feb 25, 2010
    very attractive. nice work
     

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