Gary :
I believe your car should already have the in-line fuse added by the
factory, which connects from the headlight switch to the dash light
switch. The fuse holder clips to the inside edge of the dash, below the
ignition switch. The book says this should be a 35 amp fuse (Lucas
rating method), but I use a smaller 10a fuse (US rating method). IMO
this fuse is worth adding to earlier cars, as among other things it
protects the wires to the taillights, meaning all the wires to the rear
are fused.
My book contains the notation 'fitted USA only', does anyone know if
this is true ?
Additional fuses worth considering (although I haven't tried them), with
US ratings :
1) Fusible link (16 gauge for stock generator or alternator up to 60a,
14 gauge if you have a big alternator) at the starter solenoid, in the
wire that goes to A1 on the fuse block. This protects the main wiring,
especially the wires to the ammeter.
2) 30a in the wire from A1 on the control box to the headlight switch.
Basically the 'master fuse' for everything but the horns, overdrive, and
any added 'high power' accessories (radiator fan, stereo, halogen
headlights, etc.) which should be controlled by relays fed before this
fuse (and seperately fused).
3) 15a in the wire from the headlight switch to the dimmer switch. If
you have added a headlight relay, then this fuse can go in the power
feed to the relay, and a small 5a fuse goes in the line from the
headlight switch to the dimmer switch.
If you plan to use high-power headlights (80w each or more), you will
have to increase this fuse appropriately. You need some margin in the
fuse size, to cover in-rush current, so add together the power of the
two headlights (whichever beam draws more, but not both beams) and
divide by 9 (giving a 33% margin), then round the result up to the next
common fuse size. I designed for 100w high-beams, my relay has a 25 amp
fuse.
4) If you have overdrive, I'd suggest a 'slo-blow' fuse in the power to
the OD relay (wire from ammeter to C1 on relay). It may take some
experimentation to find the smallest fuse that won't blow under normal
operation, I'd start with 12a slo-blo. In addition to protecting from
shorts in the wiring, this will hopefully also save the solenoid if it's
'pull-in' contacts don't open.
Randall
59 TR3A daily driver
Gbouff1@aol.com wrote:
>
> I am in the middle of wire harness hell, on my 59 TR3A. During the process
> of installing a new harness I remembered a thread about in line fuses quite a
> while ago. Does anybody have any recomendations on where and what amp size
> should be installed?
>
> Thanks for any input,
///
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