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275 GTB Fuse Boxes

Discussion in 'Technical Q&A' started by ehs308, Jan 31, 2014.

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  1. ehs308

    ehs308 Rookie

    Mar 29, 2011
    49
    #1 ehs308, Jan 31, 2014
    Last edited: Jan 31, 2014
    Wondering if someone can help me identify the correct fuse (amp) size for both of the fuse boxes in a 1966 275 GTB. In the process of doing a thorough cleaning of the entire relay/fuse board and found a number of fuses in poor condition and impossible to read. Despite having searched a number of resources including the owner's and shop manuals, I can't find anything on the correct fuse sizes. There are two fuse boxes with six fuses in each and they read as follows:
    BOX 1
    1. RH Full Beam Headlamp
    2. LH Full Beam Headlamp
    3. RH Dipped Beam
    4. LH Dipped Beam
    5. Park. Lights/Reverse/Boot
    6. Dome Light/Washer Pump
    BOX 2
    1. Distributors
    2. Starter
    3. Horn/Cig. Lighter
    4. Instruments-Service
    5. Dash Board Lts./Elec. Pump/Wipers
    6. Turn Signals/Stop/Elec. Fans

    Any help would be much appreciated.

    Ed
     
  2. Crowndog

    Crowndog F1 Veteran

    Jul 16, 2011
    7,042
    Fairfield,Pa
    Full Name:
    Robert
    #2 Crowndog, Feb 2, 2014
    You could get a close idea by using a simple formula: current(I)=watts(W)/volts(V) So for example 55watt headlamp/12volts=4.6amps. Then allow for a little more because of starting current to get the filament heated creating a sleight current spike and you get about 5 amp fuse. If it blows on turn on go up in 1/2 amp increments. For non bulb fuses it gets more complicated and multiple circuit.


    Sent from my iPhone using Tapatalk
     
  3. brian.s

    brian.s F1 Rookie
    Professional Ferrari Technician

    Nov 3, 2003
    3,809
    Midwest
    Full Name:
    Brian
    #3 brian.s, Feb 2, 2014
    Basically, colour code, red, black, white if I recall, 5,8, and 16 amps. Same as 308 et al. Note that isn't the clour-rating as written in that order.
     
  4. Motob

    Motob Formula 3
    Professional Ferrari Technician

    Nov 11, 2003
    2,365
    Frederick, Maryland
    Full Name:
    Brian Brown
    #4 Motob, Feb 3, 2014
    I have listed the amperages of the fuses for your 275 GTB. This is assuming that you are running regular 55/60 watt bulbs in the headlights, and have a original single Lucas cooling fan motor.

    The original 8 amp fuses that Ferrari used are black in color. Now the standard for these fuses is 8 amp (white), 16 amp (red), 25 amp (blue). Get good quality ceramic fuses (VW or BMW suppliers have them, Wurth, Winser ,etc). The cheap ones are plastic and will melt.

    Make sure that all of the fuse holders have no oxidation on them, I find that a Scotchbrite pad cleans them up nicely. Make sure that the correct cover is on the correct fusebox. The left side box will be the one with the lights and the right side box has the distributors, starter, etc.

    Regards,
    Brian Brown
    Patrick Ottis Co.
     
  5. ehs308

    ehs308 Rookie

    Mar 29, 2011
    49
    #5 ehs308, Feb 4, 2014
    Many thanks to Crowndog, brian.s and in particular Motob(Brian) for your detailed response and helpful suggestions. I found my fusebox covers were reversed when I started this project by tracing wiring via the schematic and verified their correct location as Brian noted. Spent most of yesterday removing every wire on the board and cleaning them as well as all the fuse holders with Scotchbrite, also as Brian has recommended.I am running regular 55/60 watt headlamp bulbs and have a single Lucas cooling fan.

    Many thanks again for your help.

    Ed
     

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