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275GTB Fuse box Issue

Discussion in 'Vintage (thru 365 GTC4)' started by Robert Wilder, Jul 7, 2019.

  1. Robert Wilder

    Robert Wilder Rookie

    Mar 3, 2008
    37
    Chappaqua NY
    Full Name:
    Robert H. Wilder, Jr
    i own a 1966 275 GTB long nose torque tube car. While the car was completely restored in the past 10 years the fuse boxes and wiring harness are original. The fuse box furthest to the right with the top fuse labeled Spinterogeni tends to overheat but not enough to blow the fuse but I need to spin/ replace the fuse periodically. The brass tab on this fuse holder shows signs that that tab historically gets hotter than the other fuse tabs . Also that fuse provides power to the bottom 3 fuses by way of a wire soldered to the rear of the fuse panel. I bought a reproduction fuse box which does not have the soldered wire on the back and as a result the bottom 3 fuses and all electrical devices attached to them don’t work. Anybody have any thoughts or experience with this issue?
     
  2. turbo-joe

    turbo-joe F1 Veteran
    Silver Subscribed

    Apr 6, 2008
    5,622
    southwest germany
    Full Name:
    romano schwabel
    you may clean the contacts and give more pressure to those also
    if still getting warm then meassure the amps
     
  3. Motob

    Motob Formula 3
    Professional Ferrari Technician

    Nov 11, 2003
    2,140
    Berkeley, CA
    Full Name:
    Brian Brown
    The upper fuse in the right fuse box supplies power to the ignition coils (Spinterogeni is Italian for Distributors). The power comes into the right side of the fusebox through a large white or yellow wire from the ignition switch and comes out of the fusebox on the left side through two yellow wires to the ignition coils.
    This fuse will tend to get hot if you just turn the ignition on without starting the car, as will the coil/points (on the distributor that has the points closed).

    Any excessive resistance in the fusebox will cause the fuse/fuseholders to get hot. The brass blocks that the wires are connected to are riveted to the fuse holders. Over time the rivet connections will loosen or oxidize, causing excessive resistance. I will mask off the plastic portion of the fusebox, then media blast (powder blast) the fuse box and then solder the brass blocks to the fuse holders. Replacement of the fuseblocks is also an option.

    Originally on a 275GTB the right fusebox would have a buss bar that would connect the input side of the upper fuse to the bottom three fuses. It would be riveted to the backside of the box. The large yellow/white wire powering the coils also powers the lower three fuses (gauges, electric fuel pump, turn signals and brakelights, etc.) The reproduction fusebox is not the correct box if it doesn't have this buss bar, also it sound like your original fusebox may have been modified or repaired. Is there a buss bar joining the fuses in addition to the soldered wire?

    Can you post a photo of the backside of the fusebox showing the soldered wire?

    If you want to use the reproduction box, you will have to solder a wire from the upper fuse to the lower three fuses.
     
    readplays, TTR and enio45 like this.
  4. Robert Wilder

    Robert Wilder Rookie

    Mar 3, 2008
    37
    Chappaqua NY
    Full Name:
    Robert H. Wilder, Jr
    Brian, thanks for providing such a complete and informative reply. While I need to get you full information based on your reply, the reproduction fuse box has neither a bus bar or a soldered wire connecting the distributor fuse with the bottom 3 fuses. That is the reason when I started the car with the new fuse box installed, all the devices that operate off the 3 lower fuses didn’t function. The original right hand fuse box has no Bus bar connection on the back side of the fuse box; only a wire soldered at the 3 lower fuses on the “hot” side connecting them to the distributor fuse .
     

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